Introduction

This Pilot’s Operating Handbook contains the information necessary for the safe and efficient operation of the RV-10 aircraft N720AK.

This handbook is divided into sections for quick reference:

1. General - Aircraft specifications and descriptive data
2. Limitations - Operating limitations, placards, and markings
3. Engine Information - Engine specifications and operating parameters
4. Emergency Procedures - Procedures for handling emergencies
5. Abnormal Procedures - Procedures for abnormal situations
6. Normal Procedures - Normal operating procedures and checklists
7. Performance - Performance charts and data
8. Weight and Balance - Weight and balance data and calculations
9. System Descriptions - Description of aircraft systems
10. Handling, Servicing, and Maintenance - Ground handling, servicing, and maintenance information

General

Introduction

The RV-10 is a four-place, single-engine experimental aircraft powered by a Lycoming YIO-540-D4A5 six-cylinder reciprocating engine driving a Whirlwind constant-speed propeller. The aircraft is primarily constructed of alclad aluminum using flush rivets to the maximum extent possible. N720AK is operated under FAA Experimental Amateur-Built rules.

For aircraft systems descriptions see Section 8. For systems-reference detail beyond what is needed for normal operation, see the sys-*.md pages.

Exterior Dimensions

General Specifications

Performance Specifications

Van’s published numbers for the RV-10 with a 260 HP engine. Cruise figures at 8,000 ft. Speeds are KTAS unless noted.

N720AK-specific test stalls: V~S0~ 48 / V~S~ 56 / V~S1~ 61 KIAS at ~2,190 lb test weight (see Section 2).

Engine

Fuel injection and ignition are managed by the EFII System32 electronic engine management system (dual ECU); see sys-73-efii.md. The mechanical engine reference is in sys-71-engine.md.

Propeller

Fuel

Oil

Maximum Weights

Specific Loadings

Symbols, Abbreviations and Terminology

Airspeed Terminology

Engine Terminology

Navigation and Avionics

Electrical

Weight and Balance

General

Operating Limitations

General

This section provides the operating limitations, instrument markings, color coding and basic placards necessary for the safe operation of the airplane and its systems.

Airspeed Limitations

V~NE~ is true airspeed, not indicated. At altitude, indicated airspeed at V~NE~ is lower than 200 KIAS. The Dynon SkyView shows TAS in the wind bug area; verify TAS rather than IAS when operating near V~NE~.

Stall speeds are at ~2,190 lb test weight. At max gross (2,700 lb) add approximately 10%.

Power Plant Limitations

Power Plant EFIS Markings

Tachometer

Oil Temperature

Oil Pressure

Cylinder Head Temperature

Target CHT at all power settings is < 400 °F. Do not exceed 420 °F. If CHT approaches 400 °F in climb, enrich Fuel Trim (+10 % CW on the System32 controller) or reduce climb angle.

Weight Limits

Center of Gravity Limits

CG envelope per Van’s RV-10 documentation. See Section 7 (Weight & Balance) for the loading worksheet.

Flight Maneuver Limitations

Slips in clean configuration require care. The RV-10 rudder can aerodynamically stall during slips with flaps up, resulting in a sudden and uncommanded snap roll. Slips are most predictable with flaps extended, which reduces the angle of attack required for a given airspeed and prevents rudder stall.

Spins are prohibited. The RV-10 is not approved for intentional spins, and Van’s has not demonstrated spin recovery for the type. PARE is the universal procedure if a spin is entered inadvertently — see Section 4.

Types of Operations

The airplane is approved for the following operations when equipped in accordance with FAR 91:

• Day VFR
• Night VFR
• Day IFR
• Night IFR
• Non-Icing

Fuel Limitations

Automotive Fuel (Mogas) Limitations

Lycoming SI 1070AB approves the IO-540-D series for automotive gasoline (ASTM D4814, 93 AKI). With the EFII System32, all fuel downstream of the pumps is at 45 PSI — vapor can form only in the suction lines from tank to pump, so these limits control fuel volatility and temperature, the actual vapor-lock variables. Full rationale: sys-28 Fuel System.

• Octane: 93 AKI premium for unrestricted use (SI 1070AB). 91 AKI premium only when blended with at least one-third 100LL, or at or below 75% power. Never regular or midgrade (Colorado regular is 85 AKI).
• Ethanol: E0 preferred. E10 permitted for fuel burned within ~30 days; sump carefully for phase separation after cold soaks. E15/E85 prohibited.
• Season (the controlling limit): unrestricted use only with summer-blend fuel (retail June 1 – September 15). Fuel bought outside that window is presumed winter blend (RVP up to 15 psi): do not fly it straight when fuel temperature may exceed 60 °F at takeoff — blend ≥50% 100LL or use 100LL.
• Heat soak: no takeoff on mogas with heat-soaked fuel (estimated above ~85 °F after sun or prolonged ground running) unless fuel pressure is stable at 45 ± 1 PSI during a full-power runup. Fuel temperature, not OAT, is the variable.
• Altitude: no density-altitude ceiling. Above 12,500 ft pressure altitude on mogas, monitor fuel pressure; on any fluctuation, switch tanks and descend.
• Mixing: 100LL and mogas mix freely in any ratio. For high terrain with limited landing options, keep the takeoff/landing tank 100LL-rich.
• Oil: with mogas, oil must contain Lycoming additive LW-16702 or equivalent (Aeroshell 15W-50, Phillips Victory AW). Run a tank of 100LL roughly every 75 hours, and 100LL only for 25 hours after cylinder work.

Placards

Additional Engine Information

Key Engine Data

Engine Management System

The engine is managed by the EFII System32, which replaces the stock Bendix fuel servo, magnetos, mixture cable, and engine-driven fuel pump with:

• Dual ECUs — independent fuel and ignition control. Either ECU can run the engine.
• Port fuel injection — six EFII PMI injectors (one per cylinder).
• Electronic ignition — coil packs, automotive NGK plugs in EFII SPA-6 18 → 14 mm adapters.
• Dual electric fuel pumps — Walbro GSL391 ×2, Bus Manager auto-cutover at 22 PSI Borla output absolute.
• Borla 203133 MAP-referenced fuel pressure regulator — 45 PSI injector differential setpoint (DIFF mode on Dynon).

Pilot controls reduce to: throttle, propeller, Fuel Trim knob (±50% authority on the System32 controller — replaces the mixture lever). Fuel mixture, ignition timing, accelerator-pump enrichment, and warm-up enrichment are all handled automatically by the ECU based on MAP, RPM, and temperature inputs.

For complete System32 reference see sys-73-efii.md. For the mechanical engine reference see sys-71-engine.md. For the fuel system see sys-28-fuel-system.md.

Operating Limits Reference

See Section 2 for the authoritative table. Quick reference:

Power Settings (Reference)

Cooling

CHT management on this airframe (Lycoming IO-540 with EFII System32 in an RV-10 cowl) is the primary high-power-climb concern. Per Section 2, target CHT is < 400 °F at all power settings. Do not exceed 420 °F. If CHT approaches 400 in climb:

1. Enrich Fuel Trim (+10% CW on the System32 controller).
2. Reduce climb angle (lower the nose, accept a higher airspeed and a lower vertical rate).

CHT alarms are configured in the Dynon EMS sensor config (.dfg). See sys-71-engine.md — Cooling and the EMS sensor config in Public/Configs/Dynon/.

Emergency Procedures

These procedures are derived from the efis-editor checklist file. Update the source JSON and regenerate to modify.

Engine Failures

System32 Restore Function

Run any time the engine is rough, faltering, or has quit.

• Controller Dark? … EMERG PWR ON

  a dark EFII controller means power failure, not logic — E-pwr restores the essential bus; then continue

• ECU Select … OPPOSITE ECU

  shifts fuel control to the other ECU; sensors are independent

• Fuel Pump Mode … 2

  covers a delivery fault that never tripped the 22 PSI auto-cutover

• Fuel Selector … OTHER TANK / VERIFY ON

• Fuel Pump Breakers … BOTH IN

• Fuel Trim … ADJUST

  if engine firing but rough — try richer (CW) then leaner

• Emergency Power Switch … ON

  catch-all — bypasses the Bus Manager even when the panel looks alive

Engine Failure During Takeoff Run

• Throttle … IDLE
• Brakes … APPLY
• Stop … STRAIGHT AHEAD
• Wing Flaps … RETRACT
• Fuel Selector … OFF
• Key Switch … OFF

Engine Failure Immediately After Takeoff

Pitch … ONSPEED

Landing Spot … WITHIN ±30º

above turnback altitude / per TLAR — see Turnback Procedure

• ECU Select … OPPOSITE ECU

  one shot — if no restart, commit to landing

• Fuel Selector … OFF

• Key Switch … OFF

• Wing Flaps … AS REQUIRED

  33º on short final

• Doors … UNLATCH PRIOR TO TOUCHDOWN

Engine Failure In Flight

Airspeed … BEST GLIDE 95 KIAS

NRST Button … HOLD / AP ENGAGE

AP flies to nearest field at best glide; tunes comms

Best Field … DECIDE

is the nearest field actually best? terrain, wind, surface

• System32 Restore Function … EXECUTE

  Ctrl dark→E-Pwr / ECU Sel / Pump 2 / Fuel Sel / Brkrs / Trim / E-Pwr

If engine restored:

• Continue to Nearest Suitable … MONITOR

  do not switch back to test — leave the bad ECU off

If engine not restored:

• Forced Landing … EXECUTE

  as described in Emergency Landing Without Engine Power

Engine Failure On Approach

Airspeed … ONSPEED

best glide gives more distance, but already configured for landing

Best Surface … LAND

may not be the runway — pick what works

• ECU Select … OPPOSITE ECU

  if time / altitude permits — one shot

• Fuel Selector … OFF

• Key Switch … OFF

• Doors … UNLATCH PRIOR TO TOUCHDOWN

Forced Landings

Emergency Landing Without Engine Power

• Squawk … 7700

• ELT … ACTIVATE

  do it EARLY and HIGH — an ELT transmits after a crash only about half the time, and altitude gets the signal out. Squawk plus ELT is about four seconds.

• Airspeed … BEST GLIDE / ONSPEED

  95 KIAS clean / ONSPEED with flaps

• Fuel Selector … OFF

• Key Switch … OFF

  kills ECUs; engine dies clean

• Wing Flaps … AS REQUIRED — 33º RECOMMENDED

  not available until below 90 KIAS — best glide is ABOVE the flap inhibit

• Radio Call … MAYDAY 121.5

  time permitting

• Doors … UNLATCH PRIOR TO TOUCHDOWN

• Touchdown … SLIGHTLY TAIL LOW

• Brakes … APPLY HEAVILY

Note: If you walk away and the ELT is still transmitting, turn it OFF and call the nearest ATC facility or the AFRCC — an un-cancelled 406 alert launches a search.

Turnback Procedure

Decided on the ground per pre-takeoff brief.

⚠️ WARNING: Below 200 ft AGL, turnback is non-recoverable. Land ahead.

Note: 200 ft is a floor, not a gate. There is no altitude number — the call is TLAR against turning room, wind and where the runway actually is. ONSPEED is what makes that work: it holds best sustained turn rate and smallest radius regardless of weight, bank or density altitude.

• Pitch … ONSPEED IMMEDIATELY

  single AOA reference — best blend of turn rate and stall margin

• Turn Direction … INTO CROSSWIND

  wind drifts you toward centerline during reversal

• Bank … 45º

  any less wastes altitude; any more loses stall margin

• Coordinate … BALL CENTERED

  uncoordinated stall is non-recoverable at low altitude

• On Speed … MAINTAIN TO TOUCHDOWN

Note: If there is ANY doubt about the energy to reach the runway, do not commit to it — turn into the wind and slow to ONSPEED. That is the maneuver, not a consolation prize.

Note: If turn not working: WINGS LEVEL, LAND AHEAD AS SLOW AS POSSIBLE.

Don’t stall. Everything else is secondary.

Precautionary Landing With Engine Power

Lowest sustainable energy at touchdown — drag it in with power.

• Airspeed … ONSPEED
• Wing Flaps … 16º
• Selected Field … FLY OVER
• Terrain And Obstructions … NOTE
• Wing Flaps (On Final) … 33º
• Airspeed … SLOW TONE
• Power … CONTROL DESCENT RATE
• Avionics Master … OFF
• Doors … UNLATCH PRIOR TO TOUCHDOWN
• Touchdown … SLIGHTLY TAIL LOW
• Key Switch … OFF
• Brakes … APPLY HEAVILY

Ditching

Goal is lowest sustainable energy at touchdown — fly the slow tone.

• Transmit Mayday … 121.5 MHZ, GIVING LOCATION

• Squawk … 7700

• ELT … ACTIVATE

  do it EARLY and HIGH — an ELT transmits after a crash only about half the time, and altitude gets the signal out. Squawk plus ELT is about four seconds.

• Heavy Objects … SECURE OR JETTISON

• Flaps … 16º - 33º

• Power … ESTABLISH 300 FT/MIN DESCENT, SLOW TONE

Approach:

High Winds, Heavy Seas — INTO THE WIND

Light Winds, Heavy Swells — PARALLEL TO SWELLS

• Cabin Doors … UNLATCH
• Touchdown … LEVEL ATTITUDE AT ESTABLISHED DESCENT
• Airplane … EVACUATE
• Life Vests and Raft … INFLATE

Landing With A Flat Main Tire

• Approach … NORMAL

• Wing Flaps … FULL DOWN

• Touchdown … GOOD TIRE FIRST

  hold airplane off flat tire as long as possible with aileron

Landing Without Elevator Control

• Airspeed … 80 KIAS

• Elevator Trim … LEVEL FLIGHT

• Glide Angle … CONTROL WITH POWER

• Elevator Trim … FULL NOSE UP

  in flare — rotates to horizontal for touchdown

• Throttle … CLOSE AT TOUCHDOWN

Fires

Engine Fire During Start On Ground

If engine starts:

• Fuel Pump Breakers … PULL BOTH

  stop feeding the fire — the engine runs a few seconds on residual rail pressure

• Throttle … OPEN SLOWLY / 1800 RPM

  slow push — a fast one fires the accelerator-pump squirt; airflow purges the intake until the engine starves and dies

• Key Switch … OFF

  after the engine dies

• Fuel Selector … OFF

• Doors … UNLATCH

• Evacuate / Extinguisher … AS REQUIRED

If engine fails to start:

• Fuel Pump Breakers … PULL BOTH

  fuel off FIRST — cranking with the pumps on floods the intake and feeds the fire

• Throttle … OPEN / DO NOT PUMP

  pumping the throttle fires the primer squirt

• Starter … CRANK ~10 SECONDS

  purge crank — injectors run dry in seconds once the pumps are off. Key stays ON: the starter is dead with the key off

• Key Switch … OFF

• Emergency Power Switch … OFF

  E-pwr re-powers the ECUs and the starter — must be off

• Fuel Selector … OFF

• Doors … UNLATCH

• Fire Extinguisher … AS REQUIRED

• Evacuate … IMMEDIATELY

Engine Fire In Flight

Fuel Pump Breakers … PULL BOTH

the pumps are the 45 PSI feeding a fuel fire — physical breakers beat switch logic in a fire

Key Switch … OFF

kills ECUs, both busses, and any wire-arc source

Fuel Selector … OFF

stops gravity/siphon feed to a firewall-forward leak

• Emergency Power Switch … OFF

⚠️ WARNING: With both busses dead the flaps and electric trim are gone — plan a FLAPS-UP landing. Vs1 is 61 KIAS against 48 KIAS at 33º.

E-pwr independently re-powers ECUs and pumps — both paths must be off

• Cabin Heat / Air … OFF

  close firewall vents

• Airspeed … INCREASE

  slip or dive to blow out fire

• Forced Landing … EXECUTE IMMEDIATELY

If fire not extinguished:

• Sideslip … INTO FIRE SIDE

  keep flames away from cabin

• Land … IMMEDIATELY

Electrical Fire / Smoke In Cockpit

Key Switch … OFF

the one keyed master — kills ECUs, fuel pumps, and both busses

Emergency Power Switch … OFF

⚠️ WARNING: With both busses dead the flaps and electric trim are gone — plan a FLAPS-UP landing. Vs1 is 61 KIAS against 48 KIAS at 33º.

now the airplane is fully dark

Vents / Cabin Air … OPEN

clear smoke

• Fire Extinguisher … AS REQUIRED
• Land … AS SOON AS PRACTICABLE

If engine required to reach landing site:

• Emergency Power Switch … ON

  restores engine power only — non-essential systems stay dead

• Monitor … FOR RECURRENCE

Note: If smoke returns, Emergency Power → OFF and re-isolate.

Cabin Fire

• Fire Electrical? … USE ELECTRICAL FIRE CL

  killing the key stops the engine — isolate electrics only if the fire IS electrical

• Vents / Cabin Air / Heat … CLOSED

• Fire Extinguisher … ACTIVATE

⚠️ WARNING: After discharging an extinguisher in a closed cabin, ventilate the cabin.

• Land … AS SOON AS POSSIBLE
• Airplane … INSPECT FOR DAMAGE

Wing Fire

• Navigation Light … OFF
• Strobe Light … OFF
• Pitot Heat … OFF

Note: Sideslip to keep flames away from fuel tank and cabin. Land as soon as possible. Flaps only as required for final approach and touchdown.

Electrical / Engine Malfunctions

Primary Alternator (Hartzell) Failure

Symptoms: Bat 1 voltage dropping, alternator amps zero, low-voltage indication.

• Bat 1 Voltage … CHECK

• Alternator Field Switch … CYCLE OFF / ON

  one attempt only

If still failed:

• Non-Essential Loads … REDUCE

  VPX may auto-shed; help it

• MZ-30 … VERIFY OPERATING

  Bat 2 voltage holding, generator amps positive

• Plan Diversion … NEAREST SUITABLE

  Bat 1 will eventually drain even with reduced load

If Bat 1 voltage critical:

• Emergency Power Switch … ON

  moves essential bus to Bat 2 / MZ-30

MZ-30 Generator Failure

Symptoms: Bat 2 voltage dropping, generator amps zero or low.

• MZ-30 Enable Switch … VERIFY ON

• Generator Amps … CHECK

  expect 5-30A in normal operation

• Bat 2 Voltage … MONITOR

If still failed:

• MZ-30 Enable Switch … OFF

  regulator may have OVP-locked; disable to prevent damage

• Continue on Hartzell / Bat 1 … FLIGHT NOT AT RISK

  Plan return when convenient — primary system intact

Bus Manager Failure / Switch to Endurance Bus

Symptoms: multiple essential systems unresponsive; primary bus dead.

Emergency Power Switch … ON

bypasses Bus Manager — connects Bat 2 / MZ-30 directly to essential bus

• Non-Essential Loads … OFF

  the main bus is gone: flaps, electric trim, pitot heat, transponder and audio panel are dead. Plan a flaps-up landing.

• Squawk … 7700

• Mayday Call … 121.5

• Land … AS SOON AS PRACTICABLE

⚠️ WARNING: If Emergency Power does not restore essential bus, both systems have failed. No further reversion available — land immediately.

Loss of Oil Pressure

• Confirm with Secondary Indication … OIL TEMP / NOISE

  if oil temp also rising — engine is losing oil. Likely seizure imminent.

• Power … REDUCE

  minimize damage; lowest power that maintains flight

• Best Field … LOCATE

  treat as if engine will seize

• NRST Button … HOLD

• Mayday … 121.5 / 7700

Note: Be prepared to execute Forced Landing — engine may quit at any time.

High Oil Temperature

• If Climbing … STOP CLIMB

• RPM … DECREASE

• Airspeed … INCREASE

• Fuel Trim … +10%

  richer mixture cools the cylinders

• Plan Diversion if Sustained … NEAREST SUITABLE

Runaway Trim

Avionics Master … OFF

kills power to SV-AP-PANEL — stops all trim servo commands

• Airspeed … REDUCE

  unload trim forces

• Trim … MANUALLY OVERRIDE

  with stick pressure

• Land … AS SOON AS PRACTICABLE

Note: There is no dedicated trim circuit breaker. The avionics master is the only kill switch for the trim servos.

Icing / Static

Inadvertent Icing Encounter

• Pitot Heat … ON

• Icing Conditions … EXIT

  turn back or change altitude for warmer/colder OAT

• Cabin Heat … ON

• Defroster … MAX AIRFLOW

• Engine Speed … INCREASE

  minimize prop blade ice buildup

• Land … NEAREST AIRPORT

⚠️ WARNING: With ¼ inch ice on leading edges, expect significantly higher stall speed.

• Wing Flaps … LEAVE RETRACTED
• Approach … 80-90 KIAS
• Land … LEVEL ATTITUDE

Static Source Blockage

Erroneous instrument readings suspected.

• Alternate Static Source … TOGGLE ON

  panel toggle, top left

• Airspeed … REFERENCE TABLE

  Cruise — 50 ft higher than normal

  Approach — 30 ft higher than normal

Unreliable Airspeed / Pitot Blockage

Airspeed unwinding, frozen, or disagreeing with pitch and power.

OnSpeed tone wrong or silent. AoA blank.

⚠️ WARNING: There will be NO ADAHRS cross-check error. Both units breathe the same probe, so they agree on the bad data.

Pitch and Power … SET AND HOLD

the airplane is still trimmed where it was — change nothing abruptly

• Pitot Heat … ON

  the only in-flight fix

• Altimeter / VSI … TRUST

  independent static system — unaffected by a pitot blockage

• GPS Groundspeed … CROSS-CHECK

  wind-corrected sanity check, not a replacement for airspeed

• Alternate Static … DO NOT USE

  wrong system — it corrupts altitude without helping airspeed

• Autopilot … USE IT — BUT NOT SPEED MODES

  any airspeed-driven mode chases the false reading

⚠️ WARNING: OnSpeed, Dynon AoA and the stall warning are all AoA-derived from the same probe. All three are GONE. No low-speed protection.

• Declare … IF IMC

• Land … LONG RUNWAY, SHALLOW STABLE APPROACH

  fly the profile numbers — most pilots fly too fast without airspeed

Note: Attitude itself uses airspeed and falls back to GPS, so the backup for attitude is GPS, not the second ADAHRS.

Inadvertent IMC / Upset

180º Turn In Clouds

• Wings … LEVEL ON AUTOPILOT

• Compass Heading … NOTE

• Time … NOTE

• Standard Rate Turn … INITIATE

  60 seconds for 180º

• Level Flight … MAINTAIN

• Heading … RECIPROCAL CONFIRMED

Emergency Descent Through Clouds

• Heading … EAST OR WEST

  minimizes compass swings during bank changes

• Power … REDUCE

  for 500-800 FPM descent

• Trim … STABILIZED 80 KIAS

• Turn Coordinator … MONITOR

  corrections by rudder alone; hands off the wheel

Upon breaking out:

• Normal Cruising Flight … RESUME

Upset Recovery — Power / Push / Roll

Power … ADJUST

nose-low: throttle back. nose-high: throttle forward.

Push … UNLOAD

Roll … WINGS LEVEL

shortest direction; coordinated rudder

• Recover … PITCH TO LEVEL

  after wings level, smoothly pitch to level flight

⚠️ WARNING: In a SPIRAL — airspeed and descent rate both increasing — letting go does NOT recover. Level the wings first, then raise the nose.

Spin Recovery — PARE

⚠️ WARNING: RV-10 is not approved for intentional spins, and Van’s has not demonstrated spin recovery for the type. PARE is the universal procedure if a spin is entered inadvertently.

• P - Power … IDLE

• A - Ailerons … NEUTRAL

• R - Rudder … FULL OPPOSITE ROTATION

• E - Elevator … FORWARD BRISKLY

  to break stall

Note: Hold inputs until rotation stops, then neutralize rudder and recover from dive.

Abnormal Procedures

These procedures are derived from the efis-editor checklist file.

Abnormal

Loss of Fuel Pressure

• Fuel Pressure … CHECK GREEN

  should be 45 PSI DIFF; auto-cutover trips when Borla output drops to 22 PSI absolute (Dynon DIFF varies with MAP)

• Pump 2 Annunciator … VERIFY ENGAGED

  amber on EFII controller — Bus Manager auto-cutover

If Pump 2 not engaged:

• Fuel Pump Mode … 2

  manual override

• Fuel Selector … OTHER TANK

  rules out tank issue

If pressure restored:

• Fuel Pump Mode … TRY 1/AUTO

  if Pump 1 actually failed, Bus Manager auto-cuts back to Pump 2 when Borla output drops to 22 PSI absolute

If Pump 2 fails after a cutover:

• Fuel Pump Switch … CYCLE RAPIDLY

  1/AUTO - 2 - 1/AUTO resets the latch; Pump 1 reactivates

• Plan Diversion … NEAREST SUITABLE

Single ECU Failure

Symptoms: rough running, EGT spread, ECU GRAY/RED on controller.

• ECU Select … OPPOSITE ECU

• Fuel Trim … ADJUST

  if sensor failure caused rich/lean condition

• Power … REDUCE TO SMOOTH

• Plan Diversion … NEAREST SUITABLE

Note: Once you’ve identified the bad ECU, do NOT switch back to test.

Door Open In Flight

⚠️ WARNING: FLY THE AIRPLANE FIRST.

• Airspeed … SLOW TO ~100 KIAS

  reduces airflow load on door

• Door … DO NOT ATTEMPT TO CLOSE

  cannot be re-latched against airflow

• Occupant … BRACE / HOLD

• Land … NEAREST SUITABLE

Autopilot Malfunction

Autopilot drifting, banking, or not tracking what you asked for.

Aircraft Control … MAINTAIN

• Mode Annunciation … READ IT BEFORE TOUCHING ANYTHING

⚠️ WARNING: TRK on a coupled localizer means guidance is GONE. Dynon drops NAV to TRK silently on signal loss and does NOT recapture — NAV must be re-armed by hand.

• Downgrade One Level … NAV → HDG, COUPLED → BASIC

  a simpler mode that works beats hand-flying in IMC

• Control Wheel Steering … HOLD DISCONNECT, FLY, RELEASE

  repositions the airplane without giving up the autopilot

• Autopilot … DISCONNECT

  if downgrading does not fix it

• Trim … CHECK AND RESET

  the servo may have left the airplane well out of trim

Note: Manual force on the stick slips the servo clutches, so the airplane can always be overpowered.

Note: If it will not disconnect → Runaway Trim (Avionics Master OFF).

Brake Failure

Pedal goes soft or to the floor, or the airplane pulls on rollout.

Both Sides … TEST AT ALTITUDE OR ON DOWNWIND

find out whether it is one brake or both BEFORE committing

• Pedals … PUMP

  may rebuild line pressure — usually will not

• Co-Pilot Pedals … TRY

  separate master cylinders on the right side

Runway Choice:

• Runway … LONGEST AND WIDEST AVAILABLE

  width matters more than length with one brake

• Wind … HEADWIND OVER CROSSWIND

  a crosswind FROM the failed side helps steering, but never take a crosswind over a headwind to get it

Landing:

• Touchdown … SLOWEST PRACTICAL — SHORT FIELD TECHNIQUE

• Touchdown Position … SIDE OF THE FAILED BRAKE

  the working brake will walk you across the runway — leave room

• Flaps … LEAVE AT 33º

  aerodynamic braking — this is the OPPOSITE of short-field rollout, where flaps come up to load the wheels

• Elevator … FULL AFT

• Directional Control … RUDDER, THEN GOOD BRAKE IN PULSES

  alternate the working brake against opposite rudder

• S-Turns … GENTLE, IF ROOM

  lengthens the effective rollout

• Key Switch … OFF ONLY IF GO-AROUND NO LONGER POSSIBLE

  removes residual thrust — but it is also the engine

Note: Grass beside the runway stops an airplane sooner than pavement.

Note: Taxi in slowly, or shut down and get towed.

Smoke / Smell Investigation

Use this when something smells off but no fire is visible.

• Source … ATTEMPT TO IDENTIFY

  electrical / oil / fuel / hot dust / exhaust

• Recent Switch Activations … NOTE

  anything just turned on?

• Vents … OPEN

• Plan Diversion … NEAREST SUITABLE

  do not wait for it to escalate

Note: If smoke or visible fire develops → Electrical Fire / Smoke In Cockpit.

CO Alarm In Flight

CO Guardian audible alarm above 50 PPM. Most likely source: heat muff exhaust crack.

• Cabin Heat … OFF

• Vents … OPEN

• Oxygen Mask … DON / CONSTANT FLOW

  especially at altitude — CO displaces O2 in blood

• Land … AS SOON AS PRACTICABLE

Note: Have the heat muff and exhaust inspected before next flight.

Oxygen System Failure / Hypoxia

Symptoms: lightheadedness, tunnel vision, fingernails turning blue, fatigue. EDS-4iP not pulsing.

• O2 Mode Switch … EMERGENCY (CONSTANT FLOW, ALL PORTS)

  panel toggle bypasses pulse-on-demand and supplies all ports continuously

• Cannulas / Masks … VERIFY SEATED

• Bottle Pressure … CHECK

• Descend … BELOW 10,000 FT MSL

  if symptoms persist, declare and divert

Lost Communications — IFR

Troubleshoot:

• Volume / Squelch / Frequency … CHECK

  headset jack and PTT; last assigned frequency, then the one before it

• COM 2 / FTA-850 Handheld … TRY

  GTN COM 1 rides the essential bus; the handheld is the independent radio

• Transponder … 7600

  then listen: Guard 121.5, FSS 122.2, the navaid voice channel

VMC now, or VMC encountered later:

• Continue VFR … LAND AS SOON AS PRACTICABLE

  §91.185(b) comes first — a suitable airport, not the nearest strip

IMC — route and altitude:

• Route … ASSIGNED / VECTOR / EXPECTED / FILED

  A-V-E-F: last assigned; if on a vector, direct to the fix or route in that clearance; else what ATC said to expect; else as filed

• Altitude … HIGHEST OF M-E-A, PER SEGMENT

  Minimum IFR altitude (MEA / MOCA / OROCA), Expected, Assigned — the highest of the three, re-checked at every segment

Arrival:

• Clearance limit IS an IAF … DESCEND / APPROACH AT EFC — ELSE AT ETA

  hold until the EFC time or the flight-plan ETA; never start down early

• Clearance limit NOT an IAF … LEAVE AT EFC — ELSE ON ARRIVAL, TO AN IAF

  then begin the approach as close to the ETA as possible

• Approach … ANY PUBLISHED — FULL PROCEDURE

  own choice, no vectors are coming; fly the course reversal if charted

• CTAF / AWOS … BLIND CALLS / MONITOR

  position and intentions on CTAF; lights 7 clicks; ATC is protecting the airspace on your ETA

Note: Comm regained at any point: call ATC, squawk the assigned code, continue the last clearance. After landing, close the flight plan by phone or FSS.

Normal Procedures

These procedures are derived from the efis-editor checklist file. Update the source JSON and regenerate to modify.

Memory Items

Memory Items — N720AK

These items must be performed from memory before reaching for the checklist. Practice them so they are automatic.

ENGINE FAILURE — A B C

Airspeed … BEST GLIDE / ONSPEED

Best field … LOCATE / NRST

Checklist … SYSTEM32 RESTORE

ENGINE FIRE

Fuel Pump Breakers … PULL BOTH

Key Switch … OFF

Fuel Selector … OFF

LOSS OF FUEL PRESSURE

Fuel Pump Mode … 2

Fuel Selector … OTHER TANK

ELECTRICAL FIRE / SMOKE

Key Switch … OFF

Emergency Power Switch … OFF

Vents … OPEN

LOSS OF POWER TO ELECTRONICS

Emergency Power Switch … ON

RUNAWAY TRIM

Avionics Master … OFF

UPSET RECOVERY — POWER PUSH ROLL

Power … ADJUST

Push … UNLOAD

Roll … WINGS LEVEL

INADVERTENT IMC

Wings … LEVEL ON AUTOPILOT

180º Turn … STANDARD RATE

Preflight

Preflight Inspection

Approach:

• Gust Lock … REMOVE
• Inlet Covers … REMOVE
• Pitot / AoA Cover … REMOVE
• AR(R)OW Documents … AVAILABLE

Left Wing:

• Fuel Tank Vent Opening … CHECK
• Fuel Tank Sump … DRAIN / CHECK
• Fuel Quantity … CHECK VISUALLY
• Fuel Filler Cap … SECURE
• Wing Tie-Down … DISCONNECT
• Wingtip Lights / Antennas … CHECK
• Aileron / Flap … CHECK
• Main Wheel Tire / Brake … CHECK

Empennage:

• Baggage Door … CHECK / SECURE
• Static Source Openings … CHECK
• Tail Tie-Down … DISCONNECT
• Control Surfaces … FREE / CHECK
• Lead Weights … CHECK
• ELT Antenna … CHECK

Right Wing:

• Main Wheel Tire / Brake … CHECK
• Aileron / Flap … CHECK
• Wingtip Lights / Antennas … CHECK
• Wing Tie-Down … DISCONNECT
• Fuel Quantity … CHECK VISUALLY
• Fuel Filler Cap … SECURE
• Fuel Tank Sump … DRAIN / CHECK
• Fuel Tank Vent Opening … CHECK

Nose:

• Propeller and Spinner … CHECK

  nicks, security, oil leaks

• Nose Wheel + Tire … CHECK

• Engine Inlets / Air Intake … CLEAR

  look in for nests, debris, blockage

• Engine Oil Level … CHECK

  Do not operate with less than 8 quarts.

  Fill to 9 quarts for extended flight.

• Oil Door / Preheat Plug … STOWED / SECURE

IFR Readiness

Planning:

• Weather / personal minimums … BRIEFED

  freezing level and icing margin, alternate decision, no-go time, landing-fuel number

• NOTAMs / TFRs / GPS-WAAS NOTAMs … CHECKED

• Flight plan … FILED, VOID / RELEASE PROCEDURE KNOWN

  PBN/B2C2D2O2S1 SUR/260B CODE/A9A396 RMK/EXPERIMENTAL

• Lost comm plan … AVEF / MEA BRIEFED

Airplane:

• GTN / SkyView databases … CURRENT CYCLE

• VOR check (91.171) … WITHIN 30 DAYS, LOGGED

  date, place, bearing error, signature in the log

• Pitot-static / transponder (91.411 / 91.413) … WITHIN 24 MONTHS

• Pitot heat / alternate static … TESTED

• Oxygen … QUANTITY, CANNULAS, EDS SET

  FILL THE BOTTLE ON THE GROUND — 6×18 cylinder, 2216 PSI. Top it before the trip, not after a reroute puts you high.

  crew on O2 above 12,500 after 30 min, continuously above 14,000

Cockpit:

• iPad / ForeFlight … CHARGED, PLATES CURRENT
• Phone … PLATE PHOTOS AS BACKUP
• FTA-850 handheld … CHARGED, STOWED
• Flashlight (night) … ABOARD
• Clearance … COPIED, READ BACK, VOID TIME NOTED
• Bugs … HDG / ALT / CDI SOURCE SET
• Takeoff briefing … ABORT POINT NAMED

Before Starting Engine

• Preflight Inspection … COMPLETE

• Seats, Belts, Shoulder Harnesses … ADJUST AND LOCK

• Doors … LOCKED

• Circuit Breakers … ALL IN

• Left Panel Switches … UP / NORM

• Start Battery Select … BOTH

• Avionics Master … OFF

• Autopilot Switch … OFF

• Key … ON

• OnSpeed … BLINKING

• Fuel Pump Mode … 2, THEN 1/AUTO

  verify Pump 1 GREEN

• ECU Select … ECU1

• Fuel Quantity Indicators … CHECK

• Fuel Selector … CYCLE BOTH TANKS

  pump running — pause on each tank until pressure steadies at 45 PSI; purges bubbles from both feed lines, proves both pickups and the selector

• Fuel Selector … FULLEST TANK

• Fuel Pressure … 45 PSI / GREEN

• Brakes … TEST AND SET

Starting Engine

• Propeller … HIGH RPM

• Throttle (Prime) … 2 PUMPS COLD / 1 PUMP WARM

  watch for AP indicator on EFII controller per pump

• Throttle … OPEN 1/4 INCH

  If cold, wait 10s for primer fuel to evaporate

• Propeller Area … CLEAR

• Starter … PRESS

  release after engine starts

If engine doesn’t start within 5 revolutions:

- disengage starter,

- wait ~10s for primer fuel to evaporate,

- retry start.

After Engine Starts:

• RPM … ADJUST TO 700

  reset to 700 as engine warms up

• Oil Pressure … GREEN

  if not in green within 30 seconds — shut down

• Avionics Master … ON

• Autopilot Switch … ON

• Strobes … ON

• Alternator Current … VERIFY POSITIVE

• Radios … SET / AWOS / ATIS

• Altimeter … SET

• Heading Indicator … SET

Before Taxi

• Wing Flaps … RETRACT, VERIFY UP
• Fuel Trim … LEAN -10% FOR TAXI
• Lights … AS REQUIRED
• Brakes … TEST ON ROLL

Runup

Note: ECU controller colors: BLUE = active fuel control. GREEN = standby. RED = p-lead grounded (ignition off). GRAY = not communicating.

• Fuel Trim … 0%
• Doors … CLOSED AND LOCKED
• Elevator and Rudder Trim … TAKEOFF
• Flight Controls … FREE AND CORRECT
• Flight Instruments … SET

Governor Cycle:

• Brakes … HOLD

• Throttle … 2000 RPM

• Propeller Control … 1800 RPM

• Throttle … +2“ MP

  let RPM stabilize

• Propeller Control … HIGH RPM

ECU + Fuel System Check (1600 RPM):

• Throttle … 1600 RPM

• Ignition (ECU p-leads) … CHECK

  1 OFF, Both, 2 OFF, Both

  expect ~100 RPM drop / smooth running per side

  verify active BLUE / disabled RED on EFII controller

  at Both, verify ECU1 BLUE / ECU2 GREEN

• ECU FUEL SEL … PRI / SEC / PRI

  verify active GREEN, backup BLUE through transitions

• Fuel Pump Mode … 1 / 2 / 1/AUTO

  fuel pressure should not budge through cutover

  verify pump annunciators follow selection (active green)

• Engine Instruments (Oil Px, Temp) … CHECK

• MZ-30 Generator … VERIFY OUTPUT

  Bat 2 voltage charging; gen amps positive (won’t show at idle)

• Throttle … IDLE

Before Takeoff

Note: If this checklist is interrupted — a door, a radio call, a taxi hold — start it again from the top. The oversight a distraction causes shows up after the distraction is gone.

• Fuel Gauge … CHECK QUANTITY

• Fuel Pressure … 45 PSI / GREEN

• Fuel Trim … 0%

• ECU Select … ECU1

• Radios, Flight Plan … SET

• Transponder … ALT, 1200

• Strobes … AS REQUIRED

• Nav Lights … AS REQUIRED

• Pitot Heat … AS REQUIRED

• iPad / ForeFlight … CONNECTED

  Dynon WiFi — AHRS, traffic, GPS

• Flaps / Trim … SET FOR TAKEOFF

Takeoff Briefing — REACT:

• R - RPM … 2700, FULL POWER
• E - Engine gauges … GREEN
• A - Airspeed … ALIVE
• C - Centerline … TRACKING
• T - Takeoff abort point … IDENTIFIED
• Turn Direction (Engine-Out) … TOWARD CROSSWIND
• Radio Call … MAKE

Normal Takeoff

• Wing Flaps … 0º / 16º

• Centerline … ALIGN

• Power … FULL THROTTLE / 2700 RPM

  advance over ~5 seconds

• Elevator … BACK TO LIFT NOSE

  hover nose wheel; let plane fly itself off

• Pitch … ONSPEED

• Wing Flaps … UP

At 300 AGL:

• Propeller … 2500 RPM
• Climb Speed … START OF TONE / VY 95 KIAS

In Flight

Climb

• Climb Speed … VY 95 KIAS to 1000 AGL

• CHTs … MONITOR < 400ºF

  if approaching 400: Fuel Trim +10% or reduce climb angle

At 1000 AGL — Cruise Climb:

• Airspeed … 120 KIAS
• Power … FULL THROTTLE / 2500 RPM
• Engine Gauges … CHECK

Cruise

• Power … AS DESIRED

  default: full throttle / 2400 RPM

• Flaps … REFLEX

  reflex is −3° — the cruise position, less drag than 0°

• Fuel Trim … 0%

  0% is the programmed baseline. Lean of peak means trimming deliberately lean from here on EGT/CHT.

  NO MAP GUARD on the System32 — re-richen toward 0% BEFORE advancing the throttle, or a lean charge meets high MAP.

  clean LOP wants a GAMI spread under 0.5 gph; the 2026-08 sweeps ran 1.06–1.47

• Elevator + Aileron Trim … ADJUST

• Engine Gauges … CHECK

• Lights … AS REQUIRED

Pre-Maneuver

• Fuel Selector … MORE FULL

• Lights … AS REQUIRED

• Clearing Turns … PERFORM

  90º L - 90º R / 180º turn

• Maneuvering Speed … 125 AT GROSS

IFR Approach Brief — WRIMTM

Brief aloud before descent. Name the plate before W.

• Plate … NAMED / CURRENT

  airport, approach + suffix, amendment, current cycle

• Getting Established … STATED

  vectors / NoPT sector / HILPT / course reversal owed?

W R I M T M

• Weather … VS MINS / RUNWAY

  ceiling + vis vs minimums, wind vs runway; altimeter source + remote-altimeter penalty if noted

• Radios … TUNED / RIGHT BOX

  approach, tower/CTAF, AWOS; navaid ident if green needles

• Instruments … LOADED / CRS / SOURCE

  approach + transition in GTN, final course, GPS vs VLOC driving the needle

• Minimums … ALL, TOP TO BOTTOM

  sector/IAF, stepdowns, FAF crossing, DA/MDA + vis

  snowflake? apply cold-temp corrections per segment

• Time … FAF-MAP IF NEEDED

  only when no fix defines the MAP

• Missed … ACTION / CRS / ALT / FIX

  first action aloud, then lateral, altitude, hold fix

Descent

• Fuel Selector … MORE FULL
• Power … AS DESIRED
• Lights … AS REQUIRED
• Approach Loaded … TRANSITION VERIFIED
• Navaid Ident … DECODED ON GTN
• GPS Integrity … TERM / NO LOI

IFR Final Gate — LAVSFT

Established inbound, before the FAF. Verify the box — the brief was a promise, this is the audit.

• Lateral … SOURCE / HSI / CRS

  GPS vs VLOC correct — the standby-localizer trap; course pointer on final approach course

• Altitude … MINS BUG / MISSED ALT

  minimums bug set; altitude bug per missed-alt SOP

• Vertical … GP TYPE / ARMED

  protected (LPV/GS) or advisory (+V)? advisory ignores stepdowns

• Speed / Config … 85 KIAS / HALF FLAPS

  from REFLEX: confirm flaps read 0 before first DOWN — a -1 start makes it a no-op

• FMA … READ ALOUD

  SkyView top bar: say what it says, not what you expect

• TDZE … HEIGHT AT MINS

  how high above the pavement at DA/MDA

Before Landing — GUMPS

G - Gas:

• Fuel Selector … FULLEST TANK
• Fuel Pump Mode … 1/AUTO
• Fuel Pressure … 45 PSI / GREEN
• Fuel Trim … 0%

U - Undercarriage:

• Gear … FIXED — VERIFIED

M - Mixture:

• Fuel Trim … 0%

P - Prop:

• Propeller … FULL FORWARD

  say it now; do it with first flap deployment

S - Switches / Seatbelts:

• Seats, Belts, Harnesses … ADJUST AND LOCK

• Lights … LANDING / TAXI

  Note: Night, non-towered: key CTAF 7x for PCL (5/3 to dim); re-key on final — 15 min timer

• Transponder … ALT

• Doors … LATCHED

• Brakes … TEST

Normal Landing

• Throttle … IDLE
• Flaps … 33º @ 87 KIAS
• Propeller … FULL FORWARD
• Pitch … ONSPEED
• Trim … ADJUST
• Throttle … MAINTAIN ALTITUDE / GLIDEPATH

On short final:

• Throttle … IDLE
• Touchdown … MAINS FIRST
• Landing Roll … HOLD NOSE WHEEL OFF
• Braking … MINIMUM REQUIRED

Postflight

After Landing

• Flaps … UP
• Elevator and Rudder Trim … TAKEOFF
• Lights … AS REQUIRED
• Pitot Heat … OFF
• Transponder … ALT, 1200

Securing Airplane

• Throttle … IDLE

• Hobbs + Tach Time … RECORD

• Avionics Master … OFF

• Autopilot Switch … OFF

• Lights … OFF

• Key Switch … OFF

  kills ECUs / fuel pumps — engine stops

• Gust Lock … INSTALL

Non-Standard Takeoff and Landing

Short Field Takeoff

• Flaps … 16º

• Power … FULL THROTTLE / 2700 RPM

• Elevator … BACK TO LIFT NOSE

  fly off; let plane accelerate in ground effect

• Climb Speed … ONSPEED / VX 80 KIAS

  until obstacles cleared

• Flaps … RETRACT

Maximum Performance Climb

• Power … FULL THROTTLE / 2700 RPM
• Airspeed … ONSPEED / VX 80 KIAS
• Fuel Selector … MORE FULL
• CHTs … MONITOR < 400ºF

Short Field Landing

Drag-it-in: behind the power curve, power for descent rate, AOA for airspeed.

• Flaps … 33º BELOW 87 KIAS

• Airspeed … SLOW TONE

  high AOA, slower than ONSPEED — touchdown speed minimized

• Power … MAINTAIN DESCENT GRADIENT

  throttle controls rate of descent at this AOA

• Trim … ADJUST

• Power … REDUCE TO IDLE

  as obstacle is cleared

• Touchdown … MAIN WHEELS FIRST

• Brakes … APPLY HEAVILY

• Flaps … RETRACT

Go Around

Note: Pressing “Nose Up” on the autopilot during a coupled approach engages go-around mode automatically.

• Power … FULL THROTTLE / 2700 RPM
• Pitch … ONSPEED
• Flaps … RETRACT
• Trim … SET FOR TAKEOFF
• Climb Speed … VY 95 KIAS

Performance

Performance figures below are Van’s published numbers for the RV-10 with a 260 HP engine, augmented with N720AK-specific test data where available. Treat the published figures as a planning reference; verify against actual aircraft performance over the course of Phase I and ongoing operation.

V-Speeds (Reference)

See Section 2 for authoritative values. Quick reference:

Stall and Approach Speeds

Stall speeds at ~2,190 lb test weight, level flight, idle power. At max gross (2,700 lb), add approximately 10%.

Operationally we fly OnSpeed AOA (solid tone) for normal approach and slow tone (drag-it-in) for short field; see OnSpeed.

Takeoff Performance

Van’s published ground-roll figures, sea level, ISA, no wind, paved runway. Van’s does not publish a 50 ft obstacle distance for the RV-10.

Apply standard corrections for density altitude, wind, runway slope, and surface (grass adds ~15%). For obstacle clearance, plan generously — the 50 ft figure is generally 1.5–2× ground roll for piston singles.

Climb Performance

Van’s published rate of climb at sea level, ISA, full power:

In practice, climb at V~Y~ (95 KIAS) until 1,000 AGL, then transition to cruise climb at 120 KIAS, full throttle, 2,500 RPM. Reduce climb angle or richen Fuel Trim if CHT approaches 400 °F.

Cruise Performance

Van’s published cruise (260 HP, 8,000 ft, ISA):

Operationally we cruise at full throttle / 2,400 RPM with Fuel Trim 0% at altitudes from 6,000 to 12,000 ft. Verify actual TAS, fuel flow, and CHT against the EFIS as the airframe accumulates hours.

Landing Performance

Van’s published ground-roll figures, sea level, ISA, no wind, paved runway, max braking. Van’s does not publish a 50 ft obstacle distance for the RV-10.

For short-field landing, fly the slow tone with power for descent control (drag-it-in technique); see Section 5 → Short Field Landing.

Range and Endurance

Van’s published range at 8,000 ft, no reserves, full 60 gal fuel, gross weight:

Plan a 45-minute reserve at cruise burn for night/IFR (FAR 91.167), 30-minute reserve for day VFR (FAR 91.151), or longer per personal minimums.

Glide Performance

Best glide is 95 KIAS with the propeller pulled to full coarse (low RPM). Pulling the prop coarse reduces drag substantially compared to leaving it at high RPM — this is the difference between a usable glide and falling out of the sky.

Confirm actual glide ratio and altitude loss with at-altitude glide tests during Phase I and ongoing operation. Record altitude lost per 360° turn at 20°, 30°, 45° bank for use in pre-takeoff turnback briefing planning per the EAA Power-Loss-on-Takeoff Working Group methodology.

Add 250–500 ft pad to measured 360° altitude loss to define “high key” altitude for turnback feasibility — see Vac’s working-group writeup.

Weight and Balance

Aircraft Identification

Datum & Reference Arms

The datum is 99.44 inches forward of the wing leading edge. All arms below are aft of datum.

Allowable CG Range

CG must remain within 107.84“ – 116.24“ aft of datum at all loadings.

Empty Weight & Balance

Aircraft was weighed empty in level flight attitude. Includes 12 quarts of oil; no fuel. Weighing date: 2025-11-18.

Empty CG = 175,730 / 1,643 = 106.96 in aft of datum.

Amendment 2026-09-08 (computed, no re-weigh)

Equipment installed after the 2025-11-18 weighing, revised by computation per AC 43.13-1B Chapter 10. The amendment sheet is carried in the aircraft with the weighing record.

Amended empty CG = 175,931 / 1,646.0 = 106.89 in aft of datum. Useful load at 2,700 lb gross is 1,054 lb. Re-weigh at the next condition inspection or major modification.

Weights and Capacities

Sample Loadings

All four scenarios use the amended empty weight (1,646 lb @ 106.89“) and assume 12 qts oil.

Most Forward CG

A light pilot with minimum fuel needs about 7 lb in the baggage area to stay at or aft of the 107.84“ forward limit; with 4 lb the CG falls to 107.77“.

Most Aft CG

Max Gross — Typical 4-Up Loading

First Flight / Single Pilot Light Loading

Sample Calculation Worksheet

Use this template for actual flights. CG = Total Moment ÷ Total Weight.

CG must be between 107.84 and 116.24 inches aft of datum.

Total weight must not exceed 2,700 lbs.

Source Documents

• Authoritative W&B sheet: Public/Weight-Balance/N720AK_WB_11_18_2025.pdf on Google Drive (2025-11-18 weighing), with N720AK_WB_amendment_2026-09-08.pdf (computed amendment; generated by scripts/wb_amendment.py).
• A ForeFlight-compatible aircraft profile export is planned so that guest pilots can compute W&B for N720AK in ForeFlight.

System Descriptions

The Airplane

The RV-10 is a four-place, single-engine, low-wing aircraft with tricycle landing gear. The airframe is primarily aluminum alloy construction with flush rivets, except for some steel components including the engine mount, landing gear legs, control surface bellcranks, and miscellaneous hardware. Wing tips, tail fairings, cowling, and wheel fairings are fiberglass.

Engine and Components

The aircraft is powered by a Lycoming YIO-540-D4A5 (S/N EL-36315-48E), 260 HP at 2,700 RPM, six-cylinder horizontally opposed, fuel injected, normally aspirated, air cooled. Compression ratio 9:1 as configured for the EFII System32. Installed new on 2025-11-18.

Electronic Engine Management

The EFII System32 provides:

• Full Electronic Ignition: Dual redundant ignition with individual coil packs for each cylinder
• Electronic Fuel Injection: Precise fuel metering with automatic mixture optimization
• Redundant ECUs: Two independent Engine Control Units; panel switch allows manual ECU selection if needed

The System32 controller on the panel provides mixture control through the electronic fuel injection system.

Detailed reference: EFII System32 (ATA 73)

Fuel Pumps

Two electric fuel pumps (primary and backup) pressurize the fuel line to the engine. The system includes:

• Automatic Switchover: If fuel pressure drops below threshold, the System32 automatically activates the backup pump
• Manual Selection: Panel switch (PMP 2) allows manual pump selection
• Fuel Return: Excess fuel returns to the originating tank

Detailed reference: Fuel System (ATA 28)

Propeller

Detailed reference: Propeller (ATA 84)

Landing Gear

The landing gear is a fixed tricycle configuration with:

• Steerable nose wheel (Beringer AV-VANS-102-01)
• Main gear with Matco WHLWI600XLT-2 wheels and brakes
• Wheel fairings on all three wheels
• Main tires: Desser retreads (no inner tubes)

Tire size and pressure values: see sys-61-brakes.md. Verify and update at next servicing — pressures are not currently logged in the maintenance data.

Brake System

Hydraulic disc brakes are operated by toe pedals on both pilot and copilot rudder pedals.

Detailed reference: Brakes & Wheels (ATA 61)

Flight Control System

Dual controls are fitted. Primary flight controls:

• Ailerons: Operated through push-pull tubes
• Elevator: Operated through push-pull tubes
• Rudder: Cable operated, connected to rudder pedals

Trim Systems

• Pitch Trim: Electric servo-actuated trim tab on elevator, controlled by hat switch on stick grip
• Roll Trim: Electric servo in wing, controlled by hat switch on stick grip
• Yaw Trim: None installed

Co-Pilot Trim Enable

A panel switch enables or disables trim authority from the co-pilot stick grip. This allows the pilot to disable co-pilot trim inputs when desired.

Flaps

Electric flap motor with position indicator on EFIS. Controlled by:

• Panel-mounted flap switch
• Stick grip switch (both sticks)

Flap positions range from reflex (−3°) to full (33°). Operational notches: 0°, 16°, 33°.

Detailed reference: Flight Controls (ATA 27)

Fuel System

Fuel is stored in two wing tanks with a selector valve on the center tunnel.

Fuel System Components

• Wing Tanks: Integral tanks in wing leading edges
• Fuel Selector: Three-position valve (LEFT / RIGHT / OFF) on center tunnel
• Fuel Pumps: Primary and backup electric pumps (see Engine section)
• Fuel Return: Returns to selected tank
• Fuel Strainer: Drain before first flight of day

Note: The fuel system does not support inverted flight.

Detailed reference: Fuel System (ATA 28)

Electrical System

Power Sources

The two charging systems are fully isolated. The primary alternator charges Battery 1 only, and the Monkworkz generator charges Battery 2 only.

A Generator Enable switch on the panel (next to the alternator field switch) controls the generator. A normally-open relay disconnects the generator from Battery 2 whenever the ignition key is off, preventing parasitic battery drain.

Bus Architecture

The electrical system uses a dual-bus architecture managed by the flyEFII System32 Bus Manager:

• Essential (Endurance) Bus: Powers critical engine systems (ignition, fuel injection, fuel pumps). Protected by conventional physical circuit breakers, one per item — including the fuel pump breakers called out in the Section 4 emergency checklists.
• Main Bus: Powers avionics and other aircraft systems via VPX Sport

Emergency Endurance Bus

The Bus Manager does not switch or shed loads. Both batteries feed the essential bus through a passive diode-OR: whichever battery is higher carries the bus, both share when they are close, and a single battery or charging-source failure changes nothing the pilot has to act on.

The EMERGENCY POWER switch is a hard jumper from that both-battery node straight to the essential bus, bypassing the key and both bus relays. Its use is the main-bus shed: EMERGENCY POWER ON, verify essential-bus voltage, then KEY OFF — in that order, because key-off with the switch off (or failed) stops the engine. In the shed state the engine, PFD 1, both fuel pumps, the autopilot servos and both charging sources keep running; the main bus (second and third displays, audio, transponder, flaps, electric trim, pitot heat) goes dark, and until the annual re-wires the GTN’s power relays the GTN goes dark with it. Annotated schematic and walkthrough: Electrical Power (ATA 24).

VPX Sport Power Distribution

The Vertical Power VPX Sport provides:

• Electronic circuit breaker protection for main bus loads
• Load monitoring and display on EFIS
• Automatic load shedding if needed
• Main bus channels are reset from the EFIS — there is nothing to pull. This applies to the main bus only; the endurance bus uses physical breakers.

Only the endurance bus has breakers you can pull, and they feed the engine. That is the reverse of a conventional airplane. Brief anyone who may reach for a breaker panel out of habit.

Detailed reference: Electrical Power (ATA 24)

Pitot-Static System

Pitot

The pitot tube incorporates a second orifice angled to measure differential pressure for Angle of Attack (AoA) display on the EFIS.

Static

The static system feeds:

• Dynon Skyview HDX AHRS
• Backup instruments (if installed)

Instrument Panel

Primary Flight Display

Dynon Skyview HDX provides:

• Primary Flight Display (PFD)
• Multi-Function Display (MFD)
• Engine monitoring
• Moving map with terrain
• Traffic display (dual-band ADS-B In)
• Autopilot interface

Navigation and Communication

Detailed reference: Navigation & Instruments (ATA 34) | Communications (ATA 23)

Autopilot

Dynon 3-Axis Autopilot with:

• Roll servo (aileron)
• Pitch servo (elevator)
• Yaw damper

Controlled via:

• Dynon autopilot panel
• Stick grip disconnect button

Detailed reference: Autopilot (ATA 22)

Transponder and ELT

ADS-B Out is 1090-only; ADS-B In is dual-band. The 978 link carries FIS-B weather and ground-relayed traffic; the 1090 link sees ADS-B Out–equipped aircraft directly, air-to-air, with no ground station needed. ICAO 24-bit address A9A396, ADS-B version 2 — both confirmed by the 2026-01-28 PAPR.

Panel Switches

Left Panel:

• Pitot Heat
• Landing Light
• Taxi Light
• Nav Lights
• Strobe Lights

Center Panel:

• Flap switch
• Alternator field
• Generator enable
• Avionics power
• Emergency power

EFII System32 Switches:

• Ignition Select
• ECU Select
• Fuel Pump Mode
• Start Battery Select

Other:

• Master switch (keyed)
• O2 mode switch (pulse/constant)
• Co-pilot trim enable
• ELT remote switch (Artex ELT 345 remote panel)

The ELT remote switch lets the beacon be activated before an off-airport touchdown rather than relying on the crash g-switch — which is the reason the forced-landing and ditching checklists call for it early and high.

Control Sticks

Both pilot and co-pilot have Tosten CS Military stick grips with identical button functions:

The flap switch is panel-mounted (one tap down: 0° → 16°; second tap: 16° → 33°; one tap up retracts fully). Flaps will not deploy above 90 KIAS (speed inhibit).

Detailed reference: Flight Controls (ATA 27) | Avionics & Wiring (ATA 42)

Oxygen System

Mountain High EDS-4iP pulse-demand oxygen system:

Operating Modes

A panel toggle selects between:

• Pulse Mode: Oxygen delivered in pulses synchronized with inhalation (normal operation, conserves oxygen).
• Emergency / Constant Flow: Continuous oxygen flow to all ports simultaneously. Use for hypoxia, mask seal issues, or if pulse mode fails. The toggle is the system on/off — there is no separate emergency switch.

See the Oxygen System Failure / Hypoxia checklist in Section 4b.

Detailed reference: Oxygen (ATA 35)

Heating, Ventilation and Defrosting

Cabin Heat

Heat is provided from a heat muff on the exhaust system. Controlled by push-pull knob on panel.

Ventilation

Fresh air is supplied through:

• Eyeball vents under instrument panel (pilot and copilot)
• NACA ducts on fuselage sides

Defrost

Windshield defrost air from the heating system.

Cabin Features

Seating

Four-place seating:

• Front: Pilot and copilot, side-by-side
• Rear: Two passengers

Restraints

Crow Kam Lock harnesses at all four seats — see sys-52-doors-airframe.md.

Baggage Area

Access through rear baggage door on the right side of the fuselage.

Exterior Lighting

Wing Tip Lights

Each wing tip contains:

• AeroLEDs Pulsar (NSP/660): 3-in-1 LED combining position light (red/green), strobe, and rear-facing white position light
• AeroLEDs AeroSun VX: Landing and taxi light with built-in wig-wag mode

Tail Light

• AeroLEDs SunTail: LED position light (white) and strobe

Lighting Controls

Detailed reference: Lighting (ATA 33)

Handling, Servicing and Maintenance

General

The airplane should be moved using a tow bar which connects to the nose wheel. The airplane may be pushed or pulled from the inboard portions of the prop blades. Do not push on the spinner!

Ground Handling

The airplane has three tie-down rings:

• One on each wing (near outboard bellcrank access panel)
• One on the tail

The tie-down rings are removable and may be kept inside the baggage compartment.

Jacking

The airplane can be jacked from:

• Tie-down ring locations
• Main spar just outboard of fuselage (protect with padded boards)

Engine Air Filter

Detailed reference: sys-71-engine.md — Alt Air Door

Brake Service

Warning: Use only MIL-PRF-83282 specification hydraulic fluid (Royco 782). Do not substitute automotive brake fluid — it will damage the seals.

Brake lining part numbers and replacement procedure: see Matco WI600 Series manual referenced in sys-61-brakes.md.

Landing Gear Service

Wheels: Matco WHLWI600XLT-2 main, Beringer AV-VANS-102-01 nose.

Tires: Desser 15x6.00-6 retreads with inner tubes on the mains (40 PSI); Michelin 5.00-5 tubeless on the Beringer nose wheel. Part numbers and tube options are in sys-61-brakes.md.

Wheel Bearings

Repack main wheel bearings with Aeroshell #5 grease at annual condition inspection.

Propeller Service

The Whirlwind WWA-RV10 is a sealed propeller — no field lubrication required. Inspect leading edges for nicks/erosion, hub for oil weeps, and spinner attachment at each preflight and condition inspection.

A 5-year manufacturer maintenance clock started at first engine run on 2025-11-18; next major prop maintenance event due 2030-11-18.

Detailed reference: sys-84-propeller.md

Oil System Service

Oil Change Procedure

1. Change oil and filter every 50 hours / 4 months (whichever first).
2. Remove and inspect oil suction screen for metal.
3. Cut filter and inspect for metal.
4. Replace crush washers as required.
5. Refill with 9 quarts (8 minimum for operation; do not exceed 12).
6. Run engine briefly and check for leaks.

50-Hour Companion Tasks

Perform these at every oil change:

Spark plugs: Remove, clean, inspect electrodes, re-gap, rotate top↔bottom.

Oil analysis: Take sample for Blackstone Labs before draining old oil.

Anti-Splat oil separator evacuation tube: Inspect where the evacuation tube enters the exhaust pipe. Remove any carbon coking or buildup that could block crankcase blowby flow. The evacuation tube is saddle-mounted to the exhaust pipe with two stainless steel clamps — look up into the tube entry point and scrape/clean any deposits. If excessive buildup is found, shorten the inspection interval. The safety bypass (0.5 PSI pop-off valve) provides a backup path if the tube blocks, but does not eliminate the need for inspection. See Anti-Splat installation guide.

PLX O2 sensor health: Check sensor health percentage on the DM-6 gauge (requires firmware V2.0+). Replace the wideband sensor if health drops below 50%. Also check reaction time — below 150ms is excellent, above 251ms indicates a degraded sensor. 100LL avgas poisons the sensor faster than mogas; expect 300-500 hours of life on avgas. See PLX Gen4 sensor diagnostics.

Fuel System Service

Fuel Strainer

Drain fuel strainer:

• Before first flight of day
• After each refueling
• Check for water and sediment

Fuel Tank Sumps

Drain each tank sump and check for water/contamination:

• Before first flight of day
• After refueling

Generator Service

Monkworkz MZ-30

The MZ-30 requires no brushes or field winding — maintenance is minimal.

Condition inspection items:

• Inspect generator mount bolts and silicon/fiberglass gasket
• Check 12 AWG phase wires from generator to regulator for chafe, routing clear of exhaust, and no tension from engine movement
• Check regulator mounting on engine mount
• Inspect Pico-Lock connectors (input and output) for security — add maintenance loops if missing
• Verify cooling ducts (3/4“ corrugated nylon) are intact and connected to both generator and regulator
• Check regulator blink code LED (4 flashes/sec = enabled and normal)
• Verify shear coupling is intact: generator should NOT rotate freely. If it does, the shear coupling has split — contact Monkworkz for replacement.
• Keep ferrous metal shavings away from generator exterior (permanent magnets)

Operational check:

With engine running and enable switch on, Battery 2 voltage should show a charging indication. The BOSCH relay (0332019155) should be energized (audible click when enable switch is toggled with ignition on).

Do not open the regulator box — adhesive inside dampens vibration, and opening risks tearing components off the circuit board.

Fuses: Input and output fuses are internal to the regulator. If either blows, the regulator likely needs service. Fuses can be tested with an ohmmeter (should show near-zero resistance). Contact Monkworkz for replacement.

Battery Service

The two charging systems are fully isolated. Do not charge with non-LiFePO4 chargers — EarthX batteries have an internal BMS and require lithium-specific charging.

Approved chargers (filed in shop):

• OptiMate Lithium 4s 5A (TM-291) — 5A maintainer
• OptiMate TM-275 v2 — 9.5A charger / maintainer / 13.6V power supply (TUNE mode for avionics work without battery drain)

Charger sleep behavior: OptiMate units enter sleep once fully charged and check voltage hourly. If a continuous parasitic load is present (panel powered for configuration), the maintainer may not detect drain and the battery can deplete. Use TM-275 TUNE mode (continuous 13.6 V) for any avionics work session that requires panel power.

Detailed reference: sys-24-electrical.md — EarthX Battery & Chargers

Lubrication Schedule

Oxygen System Service

Mountain High EDS-4iP system:

• Refill oxygen per Mountain High procedures
• Inspect cannulas and tubing
• Verify pulse delivery operation

Dynon Maintenance Log — Scheduled Items

The following items are configured in the Dynon SkyView maintenance log (SETUP MENU > SYSTEM SETUP > AIRCRAFT INFORMATION > MAINTENANCE LOG). The MAINT LOG page is accessible via MENU > MAINT LOG. Past-due items show in red at startup.

Tach-Based Items

Date-Based Items

Not in Dynon — Track Separately

Pitot Heat Check

Verify pitot heat operation before flight into potential icing conditions:

1. Turn on PITOT HEAT switch
2. Verify pitot tube warms (carefully touch)
3. Monitor current draw on VPX display

Workshop, Tools & Supplies

N720AK Build & Maintenance Reference

Overview

This page documents the tools, supplies, and workshop equipment used to build and maintain N720AK. It also collects condition inspection tips and lessons learned — access tricks, fastener notes, and reassembly gotchas that aren’t in any manual.

Specialty Aircraft Tools

Cleaveland Aircraft Tool

Industrial Services of WNY (iflyrv10.com)

Billet brackets and custom RV-10 parts:

Electronics & Sensors

PLX Devices

Mouser Electronics

Digi-Key

Hardware & General Supplies

Aircraft Spruce

Harbor Freight

Maintenance Supplies

Consumables to Keep on Hand

Wheels & Brakes

MATCO Manufacturing

Modifications & Accessories

AirWard

MotoPOD

Hardpoint kit for belly cargo pod. Correspondence with David Shelton (2015-2016). Hardpoints installed during build; pod itself was never produced for RV-10.

Gallagher Aviation

Mountain High

Savvy Aviation

Condition Inspection

Tips & Lessons Learned

Hard-won notes on access, fasteners, and reassembly — things that aren’t in any manual.

Interior Panels

• Front seat pan panels — outboard bottom screw (pilot & copilot): The outboard bottom screw on each front panel is partially blocked by the gear leg tube and the AeroSport plastic side panel. To install this screw without stripping it, pull back the plastic side panel first, then use a long screwdriver laid against the gear leg tube. Do NOT attempt to drive this screw with the plastic panel in place — you will strip the screw head.

AN/MS/NAS Fastener Cross-Reference

Van’s RV-10 plans use AN (Air Force-Navy) part numbers, but most retailers now sell under MS (Military Standard) or NAS (National Aerospace Standard) designations. The fasteners are identical — only the numbering system changed. This table maps between systems.

How to Read AN Part Numbers

Bolts (AN3-AN20): AN4-7A = AN standard, 4 = 4/16“ (1/4“) diameter, 7 = 7/8“ grip length (in 1/8“ increments), A = no drilled shank (cotter pin hole Absent). Without the “A” suffix, the shank is drilled for a cotter pin. For longer bolts: -12 = 1-1/4“ (first digit = whole inches, second = 1/8“ increments, so 1“ + 2/8“).

Hex head bolts (AN3-AN20) use the bolt number to encode diameter:

Rivets (AN426, AN470): AN426AD4-5 = AN standard, 426 = 100-degree countersunk head, AD = 2117-T4 aluminum alloy, 4 = 4/32“ (1/8“) diameter, 5 = 5/16“ length (in 1/16“ increments).

Screws (AN507, AN509, AN515, AN525, AN526): AN509-10R8 = AN standard, 509 = 100-degree flush structural, 10 = 10-32 thread, R = Phillips recess, 8 = 8/16“ (1/2“) total length.

Nuts: AN365-1032A = AN standard, 365 = elastic stop nut, 1032 = 10-32 thread, A = cadmium-plated steel. Suffix “C” = stainless steel.

Screws

Aircraft Spruce lists AN509 screws under MS24694, AN507 under MS24693, and AN515/AN526 under MS35206. AN525 washer head screws are still sold under the AN525 designation.

Solid Rivets

Aircraft Spruce lists these under the MS20426 / MS20470 numbers but cross-references the AN numbers on each product page.

Rivet sizing examples:

Bolts

AN3-AN20 bolt part numbers remain identical under the NASM designation. Aircraft Spruce and other retailers sell them under both AN and NASM numbers interchangeably. AN4-7A = NASM4-7A = 1/4“ bolt, 7/8“ grip, no cotter pin hole.

NAS6603-NAS6610 are NOT direct substitutes for AN bolts — they are close-tolerance bolts for shear applications with different specifications (160 KSI vs ~125 KSI for AN bolts).

Nuts

Aircraft Spruce sells AN365 nuts under the MS21044 number (e.g., MS21044N3 = AN365-1032A). The AN310 castle nut is sold as NASM310 with identical part numbering.

Washers

MS20002 / NAS1439 washers are for internal-wrenching (socket head) bolts only — they are NOT equivalents for AN960 or AN970.

Blind Rivets

Blind rivet dash numbers: First number = diameter in 32nds (4 = 1/8“), second number = max grip in 16ths (3 = 3/16“, 4 = 1/4“, 5 = 5/16“).

CherryMAX (CR32xx) rivets are a significant upgrade over CS4-4 and LP4-3: they have a locked spindle that creates a bulbed blind-side head similar to a solid rivet, providing higher shear and tension strength. Many builders substitute them throughout the build.

Nutplates (Anchor Nuts)

Nutplates are riveted to structure with AN426AD3 rivets (typically -3.5 length). The K1000 series is by far the most common in RV-10 construction.

Cotter Pins & Clevis Pins

Aircraft Spruce lists cotter pins under MS24665. Example: AN380-4-5 = MS24665-355 (1/8“ dia, 1-1/4“ long).

Quick-Reference Summary

For the most common RV-10 fasteners, here is what to search for at Aircraft Spruce:

Sources

• Aircraft Spruce MS24694 (AN509)
• Aircraft Spruce MS24693 (AN507)
• Aircraft Spruce MS35206 (AN515)
• Aircraft Spruce AN525
• Aircraft Spruce AN426 Solid Rivets
• Aircraft Spruce AN365 Elastic Stop Nuts
• Aircraft Spruce AN310 Castle Nuts
• Aircraft Spruce AN960 Flat Washers
• Aircraft Spruce AN970 Large Washers
• Aircraft Spruce K1000 Nutplates
• Aircraft Spruce Cherry Rivets
• Aircraft Spruce MS24665 Cotter Pins
• Aircraft Spruce CherryMAX CR3213
• Monroe Aerospace AN960/NAS1149 Cross-Reference Chart
• Skybolt AN-MS-NAS Hardware Reference (PDF)
• Pegasus Auto Racing AN Bolt Identification
• FAA AC 43.13-1B Chapter 7 - Bolts
• Spencer Aircraft Fastener Cross-References

Hangar Facility — KBDU

Flooring

Swisstrax Ribtrax Pro interlocking tiles, Slate Grey. Wall-to-wall coverage of KBDU hangar. Custom L-shaped layout: ~41’ x 15’6“ main area with 18’6“ x 7’6“ extension.

Ordered 2026-01-26 from Swisstrax (Order #60309, rep Jacob Crawford). Total $4,337.01. Invoice filed at Private/Invoices/swisstrax-hangar-flooring-order-60309-2026-01-26.pdf.

References

All order confirmations and invoices archived to Google Drive Private/Invoices/ organized by vendor.

Autopilot

ATA Chapter 22 — N720AK Systems Reference

Overview

N720AK uses the Dynon 3-axis autopilot integrated with the Skyview HDX EFIS. The system provides roll (aileron), pitch (elevator), and yaw damper servo control. The autopilot is controlled via the Dynon autopilot panel on the instrument panel and can be disconnected instantly via the red button on the Tosten CS Military stick grip.

Components

How It Works

Known Quirk: Silent TRK Reversion on Localizer Signal Loss

Community-reported on SkyView HDX + GTN installations: a temporary localizer signal loss while coupled drops the autopilot from NAV to TRK mode with no alert, and it does not recapture when the signal returns — NAV must be re-armed manually. If the top bar shows TRK on a coupled localizer, guidance has been lost.

Control Wheel Steering (CWS)

The Dynon autopilot supports Control Wheel Steering mode. Press and hold the autopilot disconnect button on the stick grip to temporarily override the autopilot, manually fly the aircraft to a new attitude/heading, then release the button. The autopilot will hold the new state. This allows quick course corrections without fully disconnecting and re-engaging the autopilot.

Disconnect Logic

The autopilot disconnects when:

• The red disconnect button on either stick grip is pressed
• Manual force is applied to the controls (servo clutch slip)

Dynon TSB 080219 — SV42T servo pulley (COMPLIED 2026-10-02)

N720AK’s pitch servo is affected. The pulley reads as the unidirectional “wood-grain” texture (Sam), which the bulletin defines as an affected pulley regardless of whether a crack is present. Dynon Technical Support was contacted 2026-09-22 and is sending the LA pulley assembly and a shear screw replacement kit — see the repair procedure below.

Outcome, 2026-10-02 (tach 182.6): the removed pulley was not just wood-grain — it was cracked from the shear-screw bore clean through to the rim, the exact failure the bulletin describes. Replaced with the crosshatch pulley assembly; the original shear screw was left in place.

Why it matters: “This can cause poor autopilot performance and presents a risk of interfering with the flight controls.” This is a flight-controls hazard, not an autopilot-availability one — disconnecting the autopilot does not address it, because the linkage stays coupled to the elevator either way. That is why Dynon’s wording is before further flight.

Applicability. The bulletin (2019-08-02) covers the pulley on the Dynon linear actuator found on “Some Dynon Avionics SV42T Autopilot Servos (P/N 101008-003 / 101058-003)” and on some SV32/SV42 servos retrofitted with the linear actuator, received after 2011-12-13. This airplane’s pitch servo is an SV42T, P/N 101008-003, S/N 50220 — the part number is listed, and the airframe postdates the cutoff by over a decade. The bulletin is “in effect indefinitely or until superseded by a future bulletin.”

Dynon’s compliance wording: “Due to the nature of the issue, we recommend complying with this service bulletin before further flight. However, it is up to the owner/operator to determine the airworthiness of the aircraft for flight.”

Inspection procedure

1. Crack check — look for a crack running from the centre of the pulley out through the shear-screw bore. “It may be necessary to engage the autopilot on the ground and apply force to the control surface in order to load the pulley to make the crack visible.” An unloaded look can miss it. A crack alone condemns the pulley.
2. Texture read, with a magnifier. Both bulletin figures are loupe shots; the distinction is not reliable with the naked eye.

If affected — removal

Dynon allows either removal path:

• the entire servo assembly, or
• the linear actuator sub-assembly alone, per Dynon’s “Servo Arm / Capstan Removal and Replacement Instructions.”

Two safety steps apply either way:

• “ensure that any remaining linkages are secured and do not interfere with flight controls.”
• If removing only the linear actuator, “disable the servo circuit electrically to prevent misleading autopilot behavior” — disconnect the servo wiring and/or pull its fuse or open its breaker. This touches the SERVOS circuit in plans/electrical-mods-2026-annual.md.

Contact Dynon Technical Support on 425-402-0433 or support@dynonavionics.com. The bulletin says to contact Dynon, not to ship the unit blind.

The repair — LA pulley assembly + shear screw kit

Done 2026-10-02: pulley assembly replaced (crosshatch confirmed), castle nut 4 in-lb, new cotter pin. The shear screw kit was not needed — the original screw stays in place. AP SERVO CALIBRATION completed successfully the same day.

Dynon’s disposition (2026-09-22): they are sending the linear actuator pulley assembly and a shear screw replacement kit, not a replacement servo. So S/N 50220 stays in the airplane, and this is a field repair rather than a swap — no SkyView Network reconfiguration, since it is the same device on the bus.

Two Dynon documents govern it:

⚠ The two documents disagree on castle nut torque. 101156-001 Rev B says “DO NOT EXCEED 4.5 in-lb (72 in-oz)”; 103000-000 Rev C says “beyond 4 in-lbs. of torque may prevent the capstan from separating from the servo output shaft if the controls become jammed.” Use 4 in-lb — it is the lower figure and the newer document (2025 vs 2019). Over-torquing defeats the shear screw’s entire purpose, so err low.

Tools: needle-nose pliers, torque driver reading to 4 in-lb, 1/2“ SAE socket, side cutters, 5/64“ hex wrench (supplied in the kit).

Consumables: cotter pin MS24665-210 — “cotter pins should never be reused.” Castle nut is AN310-5. The kit supplies its own cotter pin, shear screw, 5/64“ hex wrench and a red Loctite 271 capsule.

Stack order, output shaft outward: pulley → nylon washer → wavy washer → castle nut (AN310-5) → new cotter pin. Finger-tighten the nut, then torque only until a slot lines up with the cotter pin hole. Servo rotation must be smooth afterwards, with no movement between the actuating component and the attachment disc.

On the shear screw. 101156-001 is explicit that for a plain pulley change the screw stays put: “DO NOT REMOVE the socket head safety shear screw… The autopilot safety shear screw should NEVER be removed or adjusted during this procedure.” The pulley has a hole that fits over the screw head. The kit is therefore a contingency for a screw found broken or damaged on teardown.

If the screw does need replacing (103000-000 Rev C):

• The attachment disc has three threaded holes, so a servo accepts at most two field shear-screw replacements before it must go back to Dynon.
• The broken screw’s threaded shaft stays in the disc. Check it for burrs and file smooth. If that shaft is loose and rotating in the threads it must come out — “If the loose shear screw shaft vibrates out of the servo attachment disc, it may jam the flight controls.” If it will not come out, the servo goes back to Dynon.
• Only a Dynon shear screw. Any other fastener “will void the servo’s warranty and can cause the aircraft to be unsafe for flight.”
• Light strip of red Loctite 271 on one side of the lower half of the threads; fit into an unused hole; 5/64“ hex, hand strength only, head fully seated against the disc. Under-seating or over-tightening both cause premature failure.
• Cure: 15 minutes before refitting the pulley, and a minimum of one hour before flight.

Finally, recalibrate. 103000-000 Rev C closes with “Perform servo calibration procedure provided in the appropriate installation manual.” On SkyView that is SETUP > HARDWARE CALIBRATION > AP SERVO CALIBRATION > CALIBRATION. Autopilot status will not return to the top bar until it completes. Follow with a flight test and fine-tune per the tuning guide.

Check the new pulley before fitting it — crosshatch weave, plastic-like smooth finish, under a loupe. The bulletin covers only some servos by receipt date, and it is worth thirty seconds to confirm the replacement is not itself the affected design.

Roll and yaw servos. SV32/SV42 are on the bulletin’s unaffected list unless retrofitted with the Dynon linear actuator. N720AK’s roll servo installs per doc 101046-003, the capstan/pushrod kit — almost certainly out of scope. Read the label to close it out.

Compliance is tracked in ad-sb-compliance.tsv. Full bulletin: Dynon TSB 080219 — SV42T Servo Pulley.

Servo Installation

Inspection & Maintenance

References

• Actuator Component Removal and Replacement Instructions (101156-001, Rev B) — removing and refitting the LA pulley; castle nut AN310-5, cotter pin MS24665-210.
• Servo Shear Screw Replacement Kit Installation Guide (103000-000, Rev C) — kit P/N 102991-000; three disc holes, two field replacements maximum.
• Dynon TSB 080219 — SV42T Servo Pulley (2019-08-02) — the pulley cracking bulletin; N720AK’s pitch servo is affected.
• Dynon SkyView Autopilot In-Flight Tuning Guide (Rev F)
• Dynon SkyView System Installation Guide (Rev AX)
• Dynon AP Roll Servo for RV-10 Right Wing (Doc 101046-003, Rev H) — Kit P/Ns: 100870-001 Right Roll Bracket, 100872-001 Right Support Bracket, 100966-008 Aluminum Pushrod 3.0“, 100836-000 Large Male Rod End. Hardware: AN3H-3A, AN3H-10A, AN3H-17A, AN970-3, AN365-1032A.
• Dynon AP Pitch Servo for RV-10 Linear Actuator (Doc 101046-007, Rev E) — Kit P/Ns: 100973-002, 100836-000, 100982-001.
• Dynon AP Yaw Tiller Arm/Bow Kit for RV-10/14 (Doc 102710-000, Rev A) — Kit P/Ns: 102701-000, 102702-000, 100904-001, 100905-000, 101877-000.

Communications

ATA Chapter 23 — N720AK Systems Reference

Overview

N720AK’s communications stack includes the Garmin GMA 245 audio panel, Dynon Com Panel, and intercom system. The audio panel provides Bluetooth connectivity for phone calls and music.

Components

How It Works

NAV Audio (VOR/ILS Ident)

The GTN 650’s nav receiver audio (Morse ident for VOR/LOC identification) reaches the headsets through two gates in series — both must be open:

1. GTN 650: press the small right knob to activate the Nav window, then push the Volume knob to enable nav ident (an “ID” annunciation appears in the Nav window). Turning the Volume knob while the Nav window is active sets nav audio volume, independent of Com volume. (GTN 650 Pilot’s Guide §3.5.1.)
2. GMA 245: press the NAV1 key — nav receiver audio is heard only when its green in-key annunciator is lit. (GMA 245 Pilot’s Guide p. 15.)

The GTN also auto-decodes the Morse and displays the identifier next to the active nav frequency, but audible identification requires the chain above.

Related GMA 245 behaviors: the SPKR key routes selected radios to the cabin speaker (aural alerts always play on the speaker regardless); press-hold RADIO MUTE toggles intercom muting while radio (COM/NAV/AUX) audio is active.

Antennas

COM Antennas

The CI-121 is a straight vertical whip (standard Cessna-style). The CI-122 is a bent configuration designed for underside mounting.

All antenna coax is RG-400. See wing root connectors for the right wing COM antenna coax routing through the wing root CPC.

NAV Antenna

• Bob Archer (Sportcraft) — single wingtip nav antenna feeding the GTN 650. VOR, localizer and glideslope all come off this one antenna; the GTN’s glideslope diplexer is internal, so no external splitter is fitted.
• Mounted in the right wingtip. The coax reaches the panel through an inline BNC at the right wing root — see wing root connectors.

Grounding caveat specific to N720AK. Archer’s design grounds the antenna’s base strip by clamping it between the wingtip and the wing skin under the nutplate screws. N720AK’s wingtips are on piano hinges, so that path does not exist here. Anodized hinge stock is a poor RF conductor, and two RV-10 owners with hinge-mounted tips traced a wagging needle and a dead antenna to exactly this, both fixed with a strap from the base leg to the outboard rib. Verify the base leg reads under 1 Ω to the rib whenever the tip is off.

Known-good reference numbers for a stock Archer, from owners who measured: SWR under 2:1 across 108–118 MHz, and 4:1 to 6:1 at glideslope frequencies. The poor glideslope match is normal — Archer never designed for 330 MHz, and a GTN 650 works through it.

Diagnostics: plans/vor-antenna-diagnostic.md covers the RF interference survey, VNA measurement, and the antenna rebuild dimensions.

Transponder & ADS-B Antennas

See also Navigation & Instruments.

Both are non-TSO monopole antennas fed by 50 Ω RG-400 coax, with omnidirectional vertically-polarized radiation patterns.

GPS Antennas

Dynon SV-GPS-250/A

Garmin GA 35

• Installation Instructions (Rev F)

ELT Remote Switch

N720AK has a panel-mounted ELT remote switch (part of the Artex ELT 345 installation). It allows manual activation from the cockpit, so the beacon can be turned on before an off-airport landing instead of depending on the crash-activated g-switch.

This matters more than it looks: ELTs transmit after a crash only about half the time — some fail to activate, but more are separated from their antennas or buried. Activating while still airborne also gets the signal out from altitude.

The ELT Is GPS-Aided — Wiring

Confirmed from the SteinAir SkyView interconnect (SV_Interconnect.pdf, read off the drawing, 2026-09-14):

So the 406 MHz burst carries a GPS position rather than relying on Doppler resolution alone. That is worth more than it sounds: in the Embry-Riddle data cited by PilotWorkshops, mean search duration was 11.8 hours for a 406 ELT without GPS aiding against two hours with it.

Rest of the ELT DB15, same drawing:

The remote switch head wires to pins 3 and 14 (Wht/Blu and Wht/Ora).

Consequence for the position feed: the GPS data comes from the GTN, not from the ELT’s own receiver, so it is only as good as the GTN’s power and lock. In a total electrical failure the ELT still transmits on its internal battery, but without a live feed the position reverts to whatever it last had. One more reason the forced-landing checklists activate it early, while the panel is still up.

ELT Antenna

Antenna Summary

Wiring

GTN 650 → GMA 245 Audio Connections

Pin assignments traced on the SteinAir SkyView Interconnect schematic (verified visually end-to-end, 2026-08). Both runs are shielded twisted pairs with backshell-grounded shields:

The GMA 245’s NAV 2 input (J1-19/20) is unwired — the GTN is the only nav receiver. GTN nav audio and GTN alert audio arrive on separate audio panel inputs (NAV1 key vs. always-on alert input).

COM audio routing per the same drawing: GTN 650 com (P1003) is the GMA 245’s COM 1; the Dynon SV-COM C25 is COM 2.

Backup NavCom — Yaesu FTA-850 (handheld)

Carry-aboard backup transceiver (purchased 2026-08). COM 118–136.975 MHz transmit/receive, plus VOR and ILS CDI display on the NAV band (108–117.975) and a built-in GPS with waypoint/route navigation — so a total electrical failure still leaves com, a nav needle, and a position source. Nav functions are supplemental aids only, per Yaesu.

In the box (FTA-850L): SBR-39LI 7.2 V 2200 mAh lithium pack (~10 hr receive-heavy; 5.5 hr fast charge in the cradle), SAD-25 AC charger + SBH-11 cradle, SDD-12 cigarette-lighter DC adapter (12–24 V — runs off the panel power port), SCU-42 headset adapter cable (aviation headset → radio), SBT-12 alkaline AA tray (do NOT put rechargeables in it — no protection circuits), SRA-20A antenna, belt clip, USB cable.

Condensed operating guide

• 121.5 in one action: press and hold [121.5] — four beeps, tuned. Works even with the keypad locked. Exit: [COMM], confirm YES.
• Frequency entry: five keypad digits (134.35 → 1-3-4-3-5; trailing 5/0 of 8.33-style channels auto-completes), or the outer DIAL knob. [ENT] on the freq field recalls a recently-used list.
• Volume/squelch: inner knob = volume; hold SQL to open squelch for setting level against noise. Monitor switch un-mutes weak signals.
• Transmit: PTT on the left side; speak close to the grille mic (it’s waterproof-sealed and needs directed voice) — or use the SCU-42 with a real headset, which is the plan in the airplane.
• Memories: 400 channels in 9 groups. MENU → MEMORY → group → ▲/▼. [SAVE] from COMM mode stores the current freq. Bulk-load from a browser with the FTA-850 Memory Book Programmer (Chrome/Edge, USB, no driver) or Yaesu’s Windows-only YCE46 software — preload home/mission channels (KBDU, KBJC, KLMO, Denver App sectors, KEGE and mountain AWOS/CTAFs, Flight Service 122.2).
• VOR: tune a NAV-band VOR frequency and the CDI screen appears automatically — compass rose, deviation needle, TO/FROM, GPS speed-over-ground. Set the course: [FUNC] → OBS → enter the radial.
• ILS: tune the localizer frequency; LOC and GS needles display automatically. Combined with GPS groundspeed this is a genuine get-down-through-a-layer backup.
• Dual watch: polls a priority channel while listening to another (SETUP → COMM Setup sets the priority; FUNC menu toggles it).
• Weather: NOAA weather channels via MENU → WX; GPS position readout under the GPS menu for the “where am I” call.
• Battery discipline: battery-saver sleep cycles are on by default; the display battery icon blinks when charge is critical. AA tray rides in the flight bag as the deep reserve.

Carriage doctrine

• Lives charged and reachable from the pilot seat — not in the baggage area. The whole point is the panel-dark scenario.
• The SCU-42 headset adapter stays WITH the radio; using the internal mic/speaker against cabin noise at cruise is marginal.
• Rubber-duck antenna inside an aluminum cabin costs serious range — community consensus is roughly a factor of five versus an external antenna. Usable for pattern/tower work; for a real IFR lost-com the fix is an external antenna jack (BNC to a spare or belly whip) — candidate future wiring project.
• Exercised on a recurring schedule (flight-school sys-handheld-navcom drill): power on, recall a memory, hold [121.5], tune a VOR and set the OBS — so the first fumble happens on the ground.

Inspection & Maintenance

PC programming (YCE46) and the web programmer

Yaesu’s YCE46 (v1.0.0.0, 2021) is a .NET 4.6 WinForms program; its “driver” is just an INF binding the radio to Windows’ stock USB CDC-ACM serial driver (VID 26AA, PID 0024), so macOS and Linux need no driver at all. The radio must be in CP mode (hold SQL while powering on). The wire protocol is plain ASCII at 115200 8N1: tab-delimited commands with a one-byte XOR checksum (#CMDSY sync, #CVRRQ firmware version, #CEPSR status poll, #CEPRD/#CEPWR 64-byte reads and writes of a 32 KiB memory image), plus MediaTek PMTK sentences for the GPS logger. A .dat file is that raw image; model code 0352 sits at offsets 0x0100 and 0x7FFE, the 400 memory-book entries (48 bytes each) start at 0x3000, group names at 0x0300.

The web programmer in this handbook reimplements that protocol over Web Serial and edits only the memory-book areas. Source: sections/tools/fta850/; tests run with node --test tests/*.test.mjs against a fake radio. As of 2026-09 the write path has not yet been tried against the real radio.

References

• Yaesu FTA-850 Operating Manual
• Garmin GMA 245 Pilot’s Guide
• Garmin GTN 650 Pilot’s Guide
• Artex ELT 345 Manual
• Comant CI-121 Datasheet
• Comant CI-122 Datasheet
• Dynon SV-COM-425 Customer Drawing
• Bob Archer — Antennas for Aircraft
• Bob Archer — Wing Tip vs More Common Types of VOR Antennas
• AeroElectric Connection Fig. 13-12 — wingtip VOR antenna drawing (dimensions transcribed in plans/vor-antenna-diagnostic.md)
• Archer glideslope add-on — dimensioned PDF and Onshape CAD
• Bob Archer Antenna Installation Instructions
• Garmin GA 35 Installation Instructions (Rev F)
• Garmin GA 35 Product Page
• Dynon SV-GPS-250/A Product Page
• Dynon SkyView System Installation Guide
• ACR Artex 110-773 Whip Antenna
• Artex ELT 345 Manual

Electrical Power

ATA Chapter 24 — N720AK Systems Reference

Overview

N720AK’s electrical system uses a dual-bus architecture managed by the flyEFII System32 Bus Manager. Power distribution and electronic circuit breaker protection are provided by the Vertical Power VPX Sport. Two EarthX ETX900 lithium batteries provide redundant power with fully isolated charging systems: a 60-amp primary alternator charges Battery 1, and a Monkworkz MZ-30 generator charges Battery 2.

Components

How It Works

Bus Architecture

• Essential (Endurance) Bus: Powers critical engine systems — ignition, fuel injection, fuel pumps. Managed by System32 Bus Manager. Protected by conventional physical circuit breakers, one per item — these are not VPX channels.
• Main Bus: Powers avionics and other aircraft systems via VPX Sport electronic breakers.

The only physical breakers in this airplane are on the essential bus bar. Most feed the things that keep the engine running — that is the inverse of a conventional airplane, where the pullable breakers are avionics and the engine needs no electrical power at all. Anyone reaching for a breaker panel out of habit may be reaching for ignition, fuel injection, and the fuel pumps. Brief this before engine start. See sections/sys-73-efii.md for why the engine stops without them.

Essential Bus Bar Breakers

Per the SteinAir power & lighting schematic (verified 2026-08):

COM 1 / NAV 1 split: pulling COM 1 kills only the GTN’s com transceiver (stuck-mic response — screen, GPS, and VLOC keep running). Pulling NAV 1 kills the GTN main and VLOC boards; the com board keeps operating on its last frequency with no display or tuning.

Known issue (fix planned at annual — task plan: plans/electrical-mods-2026-annual.md): the GTN’s COM/NAV power relays are held closed by the AV MSTR switch from a main-bus feed — so any main-bus loss opens them and the GTN goes dark despite its essential-bus breakers being hot. Planned fix: re-source the relay coil feed from the essential bus. The transponder/ADS-B (VPX J10-7) and GMA 245/headset power (VPX J10-4) also die with the main bus; planned fixes are an essential dual-feed and a dedicated essential breaker respectively.

Display Backup Power — Deliberately Not Installed

Dynon’s SV-BAT-320 backup batteries are not part of this system, by choice. With the System32 Bus Manager arbitrating two independent EarthX ETX900 batteries on fully isolated charging systems, bus current stays stable through a single charging-source or battery failure, so the per-display backup batteries solve a problem this architecture does not have. This matches what RV builders running the Bus Manager with dual batteries have generally concluded.

Consequence worth knowing: there is no display-level power reserve. Display availability depends entirely on the bus, which is what the dual-battery and dual-charging architecture exists to protect.

How the Bus Manager Actually Works

Verified against Bus Manager Drawing 5/5A (2026-08). Three facts define the architecture:

1. The key drives the Main Bus Relay (the only control of the main bus) and, cascaded from it, the Essential Bus Relay. The IGN 1 / IGN 2 panel toggles — not the key — are the ECU enables, sitting between the ECU breakers and the ECUs.
2. The essential bus is continuously diode-OR fed from both batteries. There is no switching logic — the essential bus passively draws from whichever battery node is higher, and when the nodes are close (alternator ~14.3 V, MZ-30 ~14.2 V) both sources share load through their diodes. This is normal and by design. Diode paths drop ~0.5–0.7 V below battery voltage under load. Charge isolation is separate and intact: the alternator cannot charge Battery 2 and the generator cannot charge Battery 1.
3. The EMERGENCY POWER switch is a hard jumper from the both-battery diode node directly to the essential bus output, bypassing the key, both relays, and all Bus Manager logic. It exists for Bus-Manager-internal failure; flipping it in normal flight changes nothing observable (it arms a parallel path). The Bus Manager does not automatically shed loads — the “automatic” protection is purely the passive diode-OR.

In-flight main-bus shed maneuver: E-PWR ON → verify essential bus voltage → KEY OFF. The engine keeps running (ECUs fed from the essential bus through the IGN toggles), the main bus and everything on the VPX goes dark, and both charging sources keep working. Order is critical — key-off with E-PWR off (or failed) stops the engine. Note the interaction with the engine-fire procedure: “Key OFF” only stops the engine while E-PWR is off. Main-bus loss also kills flaps, electric trim (AP panel), and pitot heat; the AP servos are essential-fed and the autopilot remains flyable from PFD1 minus auto-trim.

Endurance bus radio behavior: The GTN 650 is COM1. If power goes out on the GMA 245, it hard-connects COM1 from the GTN 650 directly to the headphones. This ensures radio communication is maintained even if the audio panel loses power on the endurance bus.

Essential Bus Walkthrough

The picture above is the whole story of the two busses in one place; the numbered walkthrough is the version to be able to say out loud.

1. Normal. The alternator charges Battery 1 and the MZ-30 charges Battery 2 — two isolated charging systems. The two busses do not share a source. Per Bus Manager Drawing 5A, the Main Bus Relay’s contact is fed from the alternator / Battery 1 rail alone; only the Essential Bus Relay is fed from the diode-OR node, which sees both batteries. The key drives the Main Bus Relay coil and, cascaded from it, the Essential Bus Relay coil (essential bus bar → ECUs, ignition coils, pumps, PFD 1, GTN, servos).
2. Battery 1 dies — the main bus dies with it. Once the alternator stops carrying, nothing is left on that rail, so the main bus goes away while the essential bus keeps running on Battery 2 through its diode. This is automatic and it has been observed in this airplane, but there is no sensor and no logic behind it: the busses simply have different sources.
3. The alternator fails but Battery 1 is good. The main bus stays up on Battery 1 until it runs down. The failure shows as alternator amps falling to zero and bus voltage sagging — not as a battery discharge, because the shunt is on the alternator lead (see Ammeter Shunt Placement).
4. Main-bus shed (smoke, runaway load, VPX fault): EMERGENCY POWER ON → verify essential-bus voltage → KEY OFF. The switch is a hard jumper from the diode node to the essential bus output, so with it on the key can open both relays without touching the engine. Order is life: key off with the switch off (or failed) opens the Essential Bus Relay and the engine stops. What survives: engine, PFD 1, both fuel pumps, autopilot servos (no auto-trim), both charging sources. What dies today: the second and third displays, transponder, audio panel, flaps, electric trim, pitot heat — and the GTN, because its COM/NAV power-relay coils are fed by AV MSTR from the main bus (the annual’s fix list).
5. EMERGENCY POWER does not work. You are on whatever the Essential Bus Relay gives you: leave the key on and land now. There is no mechanical ignition or fuel fallback on this engine, and no essential breaker is an isolation tool — every one of them feeds something the engine needs.
6. Fire / secure. Key OFF and EMERGENCY POWER OFF. Both paths must be open, because the jumper alone re-powers the ECUs, the pumps, and the starter.

Verified on the ground 2026-08-29 (EMERGENCY POWER ON, key OFF): engine, PFD 1 and pumps stayed up; GTN, transponder and audio dropped.

Ammeter Shunt Placement — Reading an Alternator Failure

The system’s current shunt sits between the alternator and the system, not between the battery and the bus. The consequence for failure recognition: on an alternator failure the SkyView does not show a battery discharge — battery drain is downstream of the shunt and invisible to it. What you see is alternator amps dropping toward zero, followed by bus voltage sagging as Battery 1 begins to carry the main-bus load unassisted.

Alerting implication: because the failure won’t announce itself as a “discharge,” the EMS alerts should be tuned to catch it directly — a low-alternator-output (amps-near-zero) and/or low-bus-voltage alarm — so the first indication isn’t a slow, silent battery drain. Confirm these alarm thresholds are set on the ground. (Battery 2 / MZ-30 charging is independent and unaffected — see the MZ-30 section.)

VPX Sport

The VPX Sport provides:

• Electronic circuit breaker protection for main bus loads — these channels have no physical breakers to pull or reset; they are reset from the EFIS. (The endurance bus is separate and does use physical breakers — see Bus Architecture above.)
• Load monitoring and display on EFIS
• Per-channel overcurrent trip and thermal protection — automatic, but per channel, not bus-level
• Programmable power channels

What Is and Is Not Automatic

Nothing in this airplane senses a low bus and sheds the main bus for you. One thing does drop the main bus automatically, but by topology rather than by detection — a dead Battery 1 takes the main bus with it, because that bus has no other source (walkthrough step 2). Do not describe that as the Bus Manager shedding load; it is the absence of a source, and the Bus Manager is not aware of it.

• The Bus Manager does not shed loads. Its automatic behaviors are the passive diode-OR at the both-battery node and the fuel-pressure-triggered switch to fuel pump 2. Neither watches bus voltage. Its install instructions describe no voltage-sensing bus logic of any kind.
• The VPX Sport does not shed loads either. The word does not appear anywhere in the Rev G4 manual. Its automatic behaviors are per-channel overcurrent and thermal protection. Low voltage is detected and reported: “A low voltage condition is detected and reported by the EFIS.” Set the SkyView low-voltage alarm (the manual’s own example is 13 V) and decide what to turn off yourself.
• The main-bus shed is a manual maneuver. EMERGENCY POWER ON → verify essential-bus voltage → KEY OFF. Order is life.

The one genuinely voltage-sensing automatic response is the MZ-30’s standby regulator, which sits idle while the node is held high and engages on its own as the node sags below about 13.7 V — see the MZ-30 section.

What an alternator failure actually looks like: ALT amps fall to zero and bus voltage sags. It does not show as a battery discharge, because the shunt is on the alternator lead.

Channel Assignments

Channel names and pin numbers are read from the SteinAir power & lighting schematic; channel names are the VPX’s own (5A-8 = the eighth 5-amp output). The J-connector each pin belongs to is inferred from Vertical Power’s worksheet pinout — confirm against the VPX Sport pinout before wiring anything. Two rows corroborate it independently: the schematic’s audio and transponder pins land on J10-4 and J10-7, which is exactly what the Bus Architecture section above already recorded.

Switch Inputs (VP-X J2, DB25)

The pilot switch panel feeds the VPX’s external switch inputs rather than switching power directly. Which channels each input gates is stored in the VPX’s own configuration, not in the wiring.

AV MSTR is a DPDT switch doing two separate jobs. One pole drives VPX Switch Input #1, which gates a configured group of the channels above — that is the avionics-master function proper. The other pole (Wht/Blk) holds the GTN COM/NAV power relay coils closed, which is the known issue described under Bus Architecture. Section 4 notes a third consequence: there is no dedicated trim breaker, so AV MSTR is the only kill switch for the trim servos.

A/P MSTR is not a switch input — it feeds autopilot servo power directly (20 AWG red).

Fuses (Non-VPX)

Discrete fuses outside the VPX electronic breaker system, located above the essential bus bar behind the pilot PFD:

Monkworkz MZ-30 Generator

Installed 2026-03-09. The MZ-30 is a permanent-magnet generator driven off the engine’s vacuum pump pad, providing independent charging for Battery 2. Manual version 4, dated 2024-10-22.

Specifications

Voltage selection: Ships configured for 14.6 VDC. For lithium batteries (EarthX), the lower 14.2 VDC setting is recommended per Monkworkz Feb 2026 guidance. To select 14.2V, disconnect pin 1 (VSEL) on the input side Pico-Lock connector. Voltage is set at startup and cannot be changed while running.

N720AK is confirmed on the 14.2 V setting — flight data (2026-06 and 2026-08 logs) shows the Battery 2 node regulating at 14.20 V against the alternator’s 14.30 V. This is exactly Monkworkz’s recommended standby-generator geometry (primary slightly above the MZ).

Standby Behavior — Read This Before Toggling the Enable Switch In Flight

Per the manual (v4, Operation, p. 21), the regulator produces output only when the attached bus voltage is below 13.7 V (in addition to RPM/temperature limits). Consequences observed in flight (2026-08-31):

• Toggling enable OFF then ON in flight does not bring the generator back while the alternator is healthy — Battery 2’s surface charge holds the node above 13.7 V, so the regulator sits in standby, possibly for the rest of the flight. It re-engages on its own after landing as the node sags. This is designed standby-generator behavior, not a fault.
• The functional test of the MZ-30 is turning the alternator field OFF (briefly): the bus sags, the MZ engages within seconds, ALT back on. Toggling the MZ’s own switch proves nothing.
• Load sharing is normal: with the nodes 0.1 V apart, cruise logs show the MZ contributing ~6 A (peaks ~18 A) alongside the alternator’s ~23 A through the essential-bus diode-OR. This is supply-sharing into the essential bus, not a charge-isolation failure.

Architecture

The two battery charging systems are fully isolated:

The bus manager’s internal screw that previously allowed the primary alternator to cross-charge Battery 2 has been removed. Each battery has a dedicated charging source.

Generator → Battery 2 Wiring

The generator output connects to the Battery 2 stud inside the bus manager (Drawing 5A, bus manager installation guide page 13). A BOSCH 0332019155 normally-open relay (30A, 12V, internal diode) sits between the generator output and Battery 2 to prevent parasitic draw when the engine is off.

Relay coil power: the essential bus output, and only that — the generator enable switch is not in the coil circuit (Sam, 2026-09-23). An earlier revision of this page said “essential bus + generator enable switch”, which wrongly implied the switch was in series with the coil. This design means:

• Turning off the ignition key de-energizes the essential bus, opening the relay and disconnecting the generator from Battery 2 — regardless of enable switch position
• Turning on the master, or the emergency bus, closes the relay and connects the MZ-30 to Battery 2
• The enable switch is separate, driving the regulator’s Output pin 1 Enable. So the regulator can be connected-but-disabled, which is the state behind the floating amps reading documented below
• The generator cannot turn itself on. The Monkworkz reference diagram drives the contactor coil from the Enable node through diode D2; N720AK deliberately drives it from the essential bus instead

Note: The manual recommends connecting to the switched side of the master contactor to avoid parasitic draw from the regulator’s ~30mA diagnostic blink code circuit. The BOSCH relay achieves the same purpose.

MZ Regulator Connections

The MZ regulator is mounted on the engine mount with the following connections:

Generator side (3-phase, #6 screw terminals, 12 AWG):

• Terminal 7 (~1), Terminal 8 (~2), Terminal 9 (~3) → MZ Generator (phases can be connected in any order)

Input Molex Pico-Lock (pre-wired, 22-24 AWG):

• Pin 1: Voltage_Select (connected = 14.6V, disconnected = 14.2V)
• Pin 5: GEN_Thermistor → Generator thermistor (required — system will not produce output without it)
• Pin 6: GND

Output Molex Pico-Lock (22-24 AWG):

• Pin 1: Enable → Pilot enable switch (pin 1 to switch center, pin 6 to switch N.O.)
• Pin 2: Output_Active — pulls to ground when regulator is active and maintaining ≥14V (works with Dynon/Garmin EFIS contact inputs). Orange/brown wire, currently coiled up and unused near the Monkworkz enable switch.
• Pin 3: +i_Shunt (internal fuse used as shunt, 1.1 mΩ nominal)
• Pin 4: −i_Shunt
• Pin 5: Proportional_Current → Dynon EMS pin 31 (0–~2.7V = 0–30A, brown/blue wire)
• Pin 6: GND

Power output (#6 screw terminals, 10 AWG Tefzel):

• Terminal 17: Output_Power_Positive → BOSCH relay → Battery 2 stud (bus manager)
• Terminal 18: Output_Power_Ground (to clean metal airframe ground, no paint/corrosion)

Known issue: the amps reading floats to ~20 A with the generator disabled

Symptom (Sam, 2026-09-23): on the ground, essential bus powered, turning the generator enable switch off leaves the EMS MZ30 amps reading drifting up to about 20 A over some seconds rather than falling to zero.

What it is not. An earlier draft of this note blamed loss of regulator power — the relay opening and taking the regulator’s supply with it. That is wrong. The relay coil is driven from the essential bus output, separately from the enable switch, so with the master (or emergency bus) on the relay is closed, the MZ-30 stays connected to Battery 2, and the regulator is powered throughout. It is powered but disabled.

Working hypothesis. The regulator stops driving Output pin 5, Proportional_Current, when Enable is de-asserted, leaving that wire high-impedance rather than held at 0 V. EMS pin 31 then floats, and a floating high-Z analog input drifts slowly — which matches the “after a bit of float” behaviour.

The arithmetic corroborates the magnitude. Pin 5 is specified 0–~2.7 V = 0–30 A, and the SkyView sensor definition MONKWORKZ CURRENT carries c_x1 = 11.111 A per volt — 30 ÷ 2.7 = 11.111, so the two agree. A displayed 20 A implies 1.80 V on the pin, a plausible resting point for a floating CMOS input.

Pin 31 cannot be pulled down in configuration. The sensor-definition file states only pin 6 supports a pull-down; pins 8, 22, 23 and 31 support “no pull-up” but no pull-down. This cannot be fixed in SkyView setup.

Confirm before fixing. Essential bus on, enable switch off, measure DC volts at EMS pin 31 (or regulator Output pin 5) to airframe ground.

• ~1.8 V and drifting → hypothesis holds. Then temporarily bridge pin 31 to ground through 10 kΩ; the reading should collapse to 0 A.
• 0 V → hypothesis is wrong; something else is producing the indication.

Fix: a pull-down resistor, pin 31 to airframe ground, around 10 kΩ.

That the regulator is powered during the fault actually strengthens this. If pin 5 were driving a wrong value, a pull-down would fight it; the evidence says pin 5 is simply undriven, so a modest pull-down wins cleanly and draws only 0.27 mA at full scale. ⚠ Re-verify calibration against a clamp meter with the generator producing — if pin 5 is a resistive divider rather than a buffered output, the pull-down joins the divider and shifts the scale. The output impedance is not documented; ask Monkworkz on the same call as the pin 2 sink question.

Alternative, if the pull-down disturbs calibration: wire Output pin 2 and treat it as the authoritative producing indication. The orange/brown wire is already coiled and unused, and SkyView ships a matching sensor definition — MONKWORKZ STATUS, function CONTACT, name MZ30_S, available on all thirteen GP pins. Needs a freed pin. ⚠ Note the Monkworkz reference diagram labels pin 2 Active_High while this page records it as pulling to ground when active — settle that polarity by measurement before wiring it.

This retracts an earlier conclusion. A previous revision reasoned that because pin 31 already reads MZ-30 current, the Output Active discrete might be redundant. That is wrong: a reading that shows 20 A from a generator that is switched off cannot serve as an “is it producing” indication. Until the float is fixed, Output Active is the only trustworthy source of that fact.

Caution: The Pico-Lock connectors are delicate — add ~0.5“ maintenance loops in the connector wires, secured to nearby 12/10 AWG wires with a small pre-load toward the connector to prevent unseating.

Cooling

Both generator and regulator require cooling via 3/4“ holes in the engine baffling with corrugated nylon tubing routed from the baffling. The duct material is a force fit into the generator, regulator, and baffling holes. RTV can improve the seal.

Generator Enable Switch

Panel-mounted next to the primary alternator field switch. Controls the relay coil circuit (essential bus → enable switch → relay coil → ground).

The enable switch wiring connects pin 1 (Enable) to the switch center post and pin 6 (GND) to the switch’s normally-open terminal, grounded at the regulator end (not at the panel — grounding at the panel can cause ground loops and erratic behavior per manual section 2.1).

Startup Behavior

After engine start, when RPM exceeds ~1200, the MZ-30 performs an internal self-test (2–4 seconds). If all checks pass, it begins providing output voltage. The enable switch can be set ON as part of the pre-start checklist or activated at idle.

Protection Features

• Overvoltage Protection (OVP): Shuts down output in <1 second if overvoltage detected. If OVP triggers 3 times in one flight, system shuts down for the remainder of that flight. If this occurs across 3 separate flights (9 total OVP events), the regulator requires service/replacement from Monkworkz.
• Thermal protection: Two-stage — first reduces to half current limit, then full shutdown if temperature continues rising. Recovers automatically when temperature drops below recovery threshold.
• Current limiting: Electronic current limiting at 30A. Output fuse is internally replaceable by a repair shop only.
• Shear coupling: Located between input spline and motor shaft. Breaks if vacuum drive torque is exceeded — contact Monkworkz for replacement if generator rotates freely.

Regulator Blink Codes

The regulator has a diagnostic LED on the output side:

The Output Active pin (pin 2) also provides status: it “flashes” on an 8-second cycle (4s ground, 4s open) if the generator is overheating, providing an in-cockpit indication.

Dynon EMS Monitoring

The MZ-30’s proportional current output (pin 5, 0–~2.7V = 0–30A) is wired to Dynon EMS pin 31. This pin previously carried the CO Guardian PPM signal to the Dynon EMS — only the EMS display was removed when the wire was repurposed. The CO Guardian unit remains installed in the cabin and still provides an audible alarm above 50 PPM. The alarm is not currently wired into the GMA 245 audio panel, so it sounds in the cabin but is not heard through the headsets.

EMS general-purpose inputs — all 13 allocated

Read from the 2026-08-29 SkyView USER_CONFIG snapshot (GDrive Public/Configs/Dynon/), not from the panel. The SV-EMS-221’s general-purpose pins on the 37-pin connector are C37 pins 4, 6, 7, 8, 9, 10, 11, 12, 20, 21, 22, 23 and 31 — the set the sensor-definition file lists as supporting the 10 k / 991 Ω / 200.88 Ω pull-ups. Every one is configured.

Pin 31 monitors the MZ-30 by current — but that reading is not currently trustworthy. With the generator switched off it floats to about 20 A rather than falling to zero; see the known issue in the MZ-30 section below. Until that is fixed the current reading cannot stand in for an “is it producing” indication, so the Output Active discrete is not redundant.

Pin 9 PHEAT is the weakest claim of the thirteen. It is the only contact with its alarm OFF, so it displays pitot-heat controller status (the brown/blue status wire) without ever alerting on it. That makes it the candidate if a pin has to be freed for the CO detector. It is not useless — heater-working status is real information — so this is an owner judgement, not an obvious swap.

Non-GP pins for reference: 1 BATT1 and 2 BATT2 voltage, 14 MAIN fuel flow, 24/25 ALT ammeter shunt, 26 MAP, 32/34 and 33/35 RPM L/RPM R. Pins 19, 27/28 and 36/37 are unconfigured but are not general-purpose inputs.

References

• Monkworkz MZ-30 product page
• MZ-30 Installation and Operation Manual V4 (2024-10-22)
• VAF: Monkworkz Wiring for Amps Readout
• Bus Manager Installation Guide, Drawing 5A (page 13)

Wiring

KiCad migration: All connector pinouts and wiring data below should eventually be ported to proper KiCad schematics. The text tables here are transcribed from build notes and serve as the interim reference.

Wiring Stations (Station-by-Station Topology)

Complete wiring map of the aircraft, from tail to firewall.

Rear Tailcone

• ELT
• SunTail (rear position/strobe)
• Elevator trim servo

Tailcone / Baggage Area Junction (RIGHT)

• Elevator autopilot servo
• ADSB
• Net hub
• Battery 1 positive (large gauge)
• Battery 2 positive (large gauge)
• Main battery negative (large gauge)

Tailcone / Baggage Area Junction (LEFT)

• Alt static line from panel
• EFIS hub connection
• Starter solenoid 1 drive
• Starter solenoid 2 drive
• Starter annunciator wire
• Emergency air override (yellow and red lines)
• O₂ supply and pressure lines (blue and red)
• Oxygen wiring harness
• Pitot air hose (blue)
• AoA hose (green)

Passenger Area (LEFT)

• O₂ lines (blue and red)
• Left passenger O₂ harness
• Left door ajar sensor
• Power wire for left door ajar servos

Passenger Area (RIGHT)

• O₂ lines (blue and red)
• Right passenger O₂ harness
• Right door ajar sensor
• Power wire for right door ajar servos

Left → Center Tunnel

• Flap position sensor harness
• Flap motor wires

Wing Connection Area (LEFT)

• Pitot heat power and ground (14 AWG)
• Heated pitot status wire
• Fuel level sensor left
• AoA air hose (green)
• Pitot air hose (blue)
• 2× shielded 3-wire bundles for left lights
• Green sync wire for left lights
• 5-wire trim bundle for left roll trim

Wing Connection Area (RIGHT)

• AP splice for red, black, yellow — 3-way (rear, connector, front)
• AP bundle extension from connector
• 2× shielded 3-wire bundles for right lights
• Green sync wire for right lights
• Right wing COM antenna coax from panel (inline connector)
• Right wing NAV antenna coax from panel (inline connector)

Gear Support Mount (LEFT) — Under-Seat Terminal Blocks

• EMS ground for trim servo sensors
• Pitch trim motor power and ground
• Roll trim motor power and ground
• Roll trim position sensor
• Pitch trim position sensor
• Trim bundle from left wing
• 5V (red/white) EMS power for trim servo sensors

Gear Support Mount (RIGHT) — Under-Seat Terminal Blocks

• Green sync wire for lights
• Wig-wag power
• Nav power
• Strobe power
• Taxi power
• Landing power
• Tail light bundle from rear
• 16 AWG ground wire for lights
• AP servo black, red, yellow spliced together
• 2× 3-wire light bundles + green sync crossing to left wing root
• 2× 3-wire light bundles + green sync from right wing root

Forward Center Tunnel

• 2× red power wires for fuel pumps
• Ground wire for fuel pumps (1 wire spliced to 2)

Control Sticks (LEFT and RIGHT)

• Main bundle from SteinAir panel harness
• COM flip sensor wire

Pilot Knee Side (LEFT)

• O₂ pilot wiring harness
• O₂ lines (blue and red)

Copilot Knee Side (RIGHT)

• O₂ copilot wiring harness
• O₂ lines (blue and red)

Left Firewall Penetration — Engine Sensors

• CHT wires × 6
• EGT wires × 6
• Fuel pressure ground and data
• Oil pressure ground and data
• Oil temp ground and data
• Spliced 5V wire (red/white) for fuel pressure, oil pressure, oil temp sensors

Right Firewall Penetration — EFII / Power

• 60A fuse → bus manager
• Ammeter shunt wires
• Spark plug wires for EFII
• Ignition coil wires (71 and 88)
• Pressure sensor wires
• All remaining EFII outputs

Terminal Blocks Under Seats

Two terminal blocks located under the front seats distribute wiring between the wing roots, center tunnel, and panel.

Left Terminal Block

Right Terminal Block

Wing Root Connectors (CPC)

CPC barrel connectors (series 1, 17–18 pin) at each wing root carry all wing wiring.

Right Wing Root Exit

Left Wing Root Exit

Autopilot Servo Wiring (Wing)

Wire color mapping between the wing harness and the Dynon roll/pitch servo connector.

Dynon EMS-220 Connector (37-Pin)

Complete pinout for the SV-EMS-220 engine monitoring module. Updated 2026-03-04.

Through Firewall

Across Panel

Down Left (Under Panel)

Shared Power

Unused Pins

Panel Mounting Fasteners

Screw/bolt specs for every panel-mounted component. Useful reference for panel removal and reinstallation.