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Flight Controls

ATA Chapter 27 — N720AK Systems Reference

Overview

N720AK has dual controls (pilot and co-pilot) with push-pull tube actuation for ailerons and elevator, cable actuation for rudder. The stick grips are Tosten CS Military with multiple programmable buttons. Electric trim is provided for pitch and roll axes.

Components

ComponentPart NumberSupplierNotes
Stick grip (x2)CS Military (MS)Tosten ManufacturingPilot and co-pilot
Pitch trim servoElevator trim tab
Roll trim servoIn wing
Flap actuatorPHA-09PPH Aviation Services12V, 4A, 150 lb, 5“ stroke
Co-pilot trim switch——Panel-mounted enable/disable
Throttle quadrantQuad Arm RestAerosport ProductsCustom: throttle + prop only (no mixture — EFII)
Throttle cable176-VTT-2.25-89.5California Push-Pull
Prop cable176-VTT-2.25-64.5California Push-Pull

How It Works

Stick Grip Button Layout

ButtonFunction
TriggerPush-to-talk (PTT)
Thumb buttonAutopilot disconnect (press) / Control wheel steering (hold)
Hat switch (top)Aileron (left/right) and pitch (up/down) electric trim
Up/down toggleUp = COM1 standby↔active swap, Down = COM2 standby↔active swap
Big red button (left)COM1/COM2 flip-flop
Small flush button (front, below trigger)Not wired / unused

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

Elevator Trim Tab Setting

N720AK’s elevator trim tabs were set using Bill DeRouchey’s method (via myrv10.com trimming tips) instead of the stock Van’s procedure. The stock instructions to set both trim tabs at 35° down creates an asymmetry problem where one tab fails to rise to trail position while the other overshoots, causing tail twisting forces.

The corrected method:

  1. Move the trim servo to full nose-up position
  2. Set the starboard (right) trim tab trailing edge to 3“ below the elevator trailing edge
  3. Run the starboard trim tab to trail position
  4. Set the port (left) trim tab to trail position

The key requirement is that both trim tabs reach the neutral/trailing position at the same time, and that neither tab goes up while the other goes down.

Co-Pilot Trim Enable

A panel switch enables or disables trim authority from the co-pilot stick grip. When disabled, the co-pilot’s trim hat has no effect. This prevents inadvertent trim inputs from passengers.

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°).

Flap operation:

  • Flaps will not deploy above 90 KIAS (speed inhibit)
  • One tap down: 0° → 16°
  • Second tap down: 16° → 33° (full)
  • One tap up: returns to 0° (full retract)
  • Momentary click — no need to hold the switch

Inspection & Maintenance

Control Stick Slop Fix

The RV-10 control stick bases can develop play between the brass bushing and the welded cylinder of the stick base. On N720AK, the pilot side only had noticeable slop (co-pilot was fine). The fix was a single AN960-6 washer (sized for AN6 bolt) placed around the brass bushing so it sits against the welded cylinder. No delrin bushing replacement was needed — the original brass bushings were retained, and the single washer was sufficient to eliminate the play.

Quadrant Cable Boots

Replacement cable boots for the throttle/mixture/prop quadrant: see VAF thread on Q-43 boots.

Photos

References