FAA Flight Instructor Airplane (FIA)Aircraft Systems and InstrumentsHard
While in cruise flight, a pilot notices the electric trim wheel moving nose-down on its own without any pilot input, causing the airplane to pitch down. After the pilot overpowers the control forces with the yoke, what is the next appropriate action?
- AIncrease power and attempt to climb away from the trim issue
- BRe-engage the autopilot to override the runaway trim
- CCycle the master avionics switch to reset the system
- DPull the electric trim system circuit breaker to isolate the malfunction
Show answer & explanationAnswer & explanation
Correct answer: D. Pull the electric trim system circuit breaker to isolate the malfunction
When electric trim runaway occurs, the pilot should first overpower the control forces, then disconnect the source of the malfunction, typically by pulling the trim system circuit breaker, to prevent the motor from continuing to drive the trim. Only after isolating the runaway system should the pilot use manual trim as needed and land as soon as practicable.
Why the other options are wrong
- A. Increasing power does not address the underlying trim malfunction and may worsen control difficulty.
- B. Re-engaging the autopilot could reintroduce the same runaway command rather than fixing it.
- C. Cycling the avionics master does not necessarily remove power from the trim motor circuit.
Electric Trim Runaway
An uncommanded, continuous movement of the trim system caused by an electrical or mechanical fault, requiring the pilot to overpower the controls and isolate the trim system electrically.
- Overpower the control forces first with manual flight controls
- Pull the trim system circuit breaker to isolate the fault
- Use manual trim wheel afterward and land as soon as practicable
Memory trick: Overpower, then pull the plug — isolate the runaway trim.