TOMS RIVER, NJ, USA
N40978
PIPER PA-31-350
THE ACFT WAS CRUISING AT 8500 FT WHEN IT EXPERIENCED AN INFLT LOSS OF CONTROL. THE PLT SAID THE AUTOPILOT PITCH TRIM RAN AWAY NOSE DOWN & HE WAS UNABLE TO DISCONNECT THE AUTOPILOT PRIOR TO THE LOSS OF CONTROL. EXAM OF THE ACFT SHOWED THE LEFT ELEVATOR HORN WAS BENT DOWN & THE RIGHT ELEVATOR HORN WAS BROKEN OFF. THE AUTOPILOT WAS EXAMINED & ALL DISCONNECTS EXCEPT FOR THE ACCELEROMETER TEST FUNCTIONED PROPERLY. THE PITCH TRIM BOARD WAS FOUND IMPROPERLY INSTALLED IN THE AUTO PILOT & DID NOT MAKE CONNECTION. WITH THE ALTITUDE HOLD ENGAGED, THE AUTOPILOT WOULD HOLD THE ELEVATOR POSITION AT TIME OF ENGAGEMENT & TRIM TO KEEP THE FORCES NEUTRAL. IF THE AIRCRAFT SLOWED, IT WOULD LOSE ALTITUDE & TRIM NOSE UP. RADAR DATA SHOWED THE ACFT STARTED TO SLOW, THEN DESCENDED FROM 8500 TO 8300 FT, THEN CLIMBED TO 8900 FT. THE ACFT THEN CAME DOWN VERY RAPIDLY TO 1700 FT PRIOR TO A RECOVERY. RPRTDLY, THE PLT DID NOT TEST THE AUTOPLT BEFORE TAKEOFF. .
FAILURE OF THE PILOT TO MAINTAIN AIRSPEED AND CONTROL OF THE AIRCRAFT, AND HIS EXCEEDING THE DESIGN STRESS LIMITS OF THE AIRCRAFT. FACTORS RELATED TO THE ACCIDENT WERE: AUTOPLT MALFUNCTION DUE TO IMPROPER INSTALLATION BY MAINTENANCE PERSONNEL AND THE PILOT'S FAILURE TO PREFLIGHT THE AUTOPILOT BEFORE USING IT IN FLIGHT.
Source: NTSB Aviation Accident Database
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