Accident Narrative
According to the pilot's account, during the takeoff roll on runway 15, approximately halfway down the runway, he sensed a reduction in engine power. Assessing that he lacked sufficient altitude to clear the rising terrain ahead, he decided to steer toward a pasture located to the right of the departure end of the runway. The pilot reported that this was his last recollection until he observed the wreckage of the airplane within an airport building.
Engine Examination
Following the accident, the engine was mounted on a test stand under the supervision of National Transportation Safety Board (NTSB) personnel. Upon starting, the engine ran for several seconds while emitting white smoke before stopping. A second start produced approximately 1,500 revolutions per minute, but the engine operated roughly. It was then shut down. Inspection revealed that the No. 3 cylinder did not exhibit elevated temperature. The cylinder was removed, and the exhaust valve head was found to be missing. The piston showed impact damage consistent with contact from the exhaust valve head, and a fragment of the valve head was recovered from within the cylinder. No part number was visible on the broken valve remnants.
Metallurgical Findings
The NTSB Materials Laboratory in Washington, D.C., conducted a metallurgical examination of the No. 3 exhaust valve remnants. The fracture surface on the stem portion of the valve displayed a flat transverse plane with large-scale ratchet marks, indicative of fatigue cracking. Additionally, three distinct fatigue regions with clear crack arrest positions were identified on the fracture adjacent to the exterior surface of the stem. The exterior surface of the stem near the fracture exhibited a heavy oxide or deposit scale.
Maintenance Records
Logbook entries indicated that the engine had last been overhauled at an aircraft and engine total time of 5,880 hours. At the time of the accident, the total time was 6,646 hours. Records prior to December 12, 1995, had been lost, and the engine overhaul occurred before that date. The remaining aircraft records contained no documentation concerning the engine overhaul.