37000 Feet | Browse and search NASA's Aviation Safety Reporting System |
|
Attributes | |
ACN | 820449 |
Time | |
Date | 200810 |
Local Time Of Day | 1201 To 1800 |
Place | |
Locale Reference | airport : zzzz.airport |
State Reference | FO |
Altitude | msl single value : 6000 |
Environment | |
Flight Conditions | VMC |
Light | Daylight |
Aircraft 1 | |
Controlling Facilities | artcc : zzzz.artcc tower : zzz.tower |
Operator | general aviation : personal |
Make Model Name | PA-34-200 Seneca I |
Operating Under FAR Part | Part 91 |
Flight Phase | climbout : intermediate altitude |
Flight Plan | IFR |
Person 1 | |
Affiliation | other |
Function | flight crew : single pilot |
Qualification | pilot : atp pilot : multi engine pilot : instrument pilot : commercial pilot : cfi |
Experience | flight time last 90 days : 90 flight time total : 8550 flight time type : 700 |
ASRS Report | 820449 |
Events | |
Anomaly | aircraft equipment problem : critical altitude deviation : excursion from assigned altitude other anomaly |
Independent Detector | other flight crewa |
Resolutory Action | flight crew : overcame equipment problem flight crew : regained aircraft control flight crew : landed as precaution flight crew : declared emergency |
Consequence | other |
Supplementary | |
Problem Areas | Aircraft |
Primary Problem | Aircraft |
Narrative:
The aircraft departed IFR; in VMC; on a ferry flight. The autopilot was unserviceable; but electric elevator trim worked. The aircraft was maintaining 6000 ft; as cleared; then recleared to 11000 ft. The electric trim was used to pitch up; but the aircraft started descending; so continuous nose-up trim was selected; to try to correct this. Very quickly; the aircraft was descending at more than 1000 FPM; and required all the pilot's strength to pull the control column back; to avoid pitching down. ATC was advised that it was not possible to climb; due to control problems. The elevator trim wheel appeared jammed in the forward position; and would not move. Greater force was used; the trim wheel was freed; and was set to a position that allowed the aircraft to continue under normal control. The electric trim circuit breaker had popped. ATC was told of the control problem; and that the aircraft was returning to the departure airport. After landing and closing down; the control problem was investigated; and found to be a defective switch on the left-hand control column. If moved forward; the trim wheel motored forward. If moved back; the trim wheel still motored forward. The flight continued the next day; with the electric trim circuit breaker pulled. Comments: the pilot was an experienced CFI; meii; with over 1500 hours of multi time; of which about half was in senecas. It was extremely fortunate that the incident occurred at 6000 ft. If it had happened on takeoff; in IMC; it would have probably caused a crash. This was a very serious (and probably very rare) failure mode of the trim switch. It could have been responsible for unexplained accidents in the past; and I believe it is essential to notify the NTSB of this incident. I suggest a controlled experiment is conducted to replicate the handling characteristics of full forward trim; when using climb power.
Original NASA ASRS Text
Title: PA34 pilot reports runaway electric trim at 6000 ft. Control of aircraft is lost until trim motor circuit breaker trips.
Narrative: The aircraft departed IFR; in VMC; on a ferry flight. The autopilot was unserviceable; but electric elevator trim worked. The aircraft was maintaining 6000 ft; as cleared; then recleared to 11000 ft. The electric trim was used to pitch up; but the aircraft started descending; so continuous nose-up trim was selected; to try to correct this. Very quickly; the aircraft was descending at more than 1000 FPM; and required all the pilot's strength to pull the control column back; to avoid pitching down. ATC was advised that it was not possible to climb; due to control problems. The elevator trim wheel appeared jammed in the forward position; and would not move. Greater force was used; the trim wheel was freed; and was set to a position that allowed the aircraft to continue under normal control. The electric trim circuit breaker had popped. ATC was told of the control problem; and that the aircraft was returning to the departure airport. After landing and closing down; the control problem was investigated; and found to be a defective switch on the left-hand control column. If moved forward; the trim wheel motored forward. If moved back; the trim wheel still motored forward. The flight continued the next day; with the electric trim CB pulled. Comments: The pilot was an experienced CFI; MEII; with over 1500 hours of multi time; of which about half was in Senecas. It was extremely fortunate that the incident occurred at 6000 ft. If it had happened on takeoff; in IMC; it would have probably caused a crash. This was a very serious (and probably very rare) failure mode of the trim switch. It could have been responsible for unexplained accidents in the past; and I believe it is essential to notify the NTSB of this incident. I suggest a controlled experiment is conducted to replicate the handling characteristics of full forward trim; when using climb power.
Data retrieved from NASA's ASRS site as of May 2009 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.