NTSB Identification: LAX99LA023.
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Accident occurred Wednesday, November 04, 1998 in MAMMOTH, CA
Probable Cause Approval Date: 06/22/2000
Aircraft: Piper PA-46-350P, registration: N50JG
Injuries: 2 Serious,2 Minor.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
Witnesses said the aircraft took off prematurely and over rotated to a nose high attitude. Shortly thereafter, the aircraft hit the ground tail first then the nose. The aircraft veered off the side runway and came to rest on a taxiway. The winds were reported as calm at the time. The pilot told the witness that he stalled on takeoff. Immediately after the accident, the position of the elevator trim tab and the cockpit elevator trim indicator were found in the full nose up trim positions. The pilot reported that the aircraft had a dead battery and required external power for the start. During this process, the autopilot cycled twice. The pilot stated that he performed a normal run-up and trimmed the aircraft for takeoff. He said that at 62 knots the autopilot ran the pitch trim to the full nose up position and the aircraft pitched prematurely to a nose high attitude and lifted off the ground. The pilot then retracted the landing gear. The left wing dropped and the airplane settled back to the ground. According to the auto pilot manufacturer, the pitch servo capstans are designed with a clutch that will slip at 25 pounds of control wheel force. According to flight test data supplied by Piper, the control wheel force required to hold 62-knot speed at full trim tab deflection would be less than 40 pounds.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: The pilot's failure to ensure that the autopilot was off prior to takeoff, and, his failure to maintain pitch control during the resultant pitch trim excursion during the takeoff ground roll. Full narrative available
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