Pilot Debrief

PIPER PA-34-200T near Saginaw, TX — 2009-11-17

Final reportCEN10LA052
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Date
2009-11-17
Location
Saginaw, TX, USA
Airport
T67
Aircraft
PIPER PA-34-200T
Registration
N8297P
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Initial climb

Probable cause

The pilot's inability to maintain control of the airplane due to a pinched trim system wire that resulted in a runaway nose-down pitch trim.

NTSB narrative

The pilot said that he took off and did not engage the autopilot, but did use the electric trim switch on the control yoke to establish a climb attitude after takeoff. When he activated the trim switch, the airplane "pitched down rapidly." Despite his application of full up elevator to arrest the descent, the airplane continued to descend. The pilot was forced to make a landing in an open field. During the ensuing forced landing, the airplane sustained substantial damage to both wings and fuselage. The pitch trim drum inner shaft was found to be in the full-nose-down position. Examination of the cockpit revealed all circuit breakers were closed and the master switch had been secured. The flight computer, trim servo, directional gyro, flight command indicator, pictorial navigation indicator, and control yoke were functionally tested and no defects were noted. The original control yoke trim switch had been replaced. The switch wiring was not the original wiring and did not correspond to the original color codes on the wires. The wire colors were written on pieces of masking tape which were wrapped around each corresponding wire. One of the wires was pinched and pressing on the switch wafer stack; according to a representative of the manufacturer the pinched wire pressing on the switch wafer stack could have resulted in a runaway trim condition.

Analysis

Primary failure mode
Mechanical failure
First missed decision gate
Pilot could have checked autopilot alignment before takeoff.

NTSB coding

Evidence available

  • Photos
  • 7 docket documents
View NTSB final reportView NTSB docket

Docket documents7

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