NTSB Factual Report

On December 31, 2011, about 1220 eastern standard time, a Piper PA-32-260, N997TB, sustained substantial damage during a forced landing to a field after a loss of engine power near Elk Rapids, Michigan. The commercial pilot and three passengers were not injured and one passenger received minor injuries. The airplane was registered to Bulldog Air LLC and operated by the pilot as a personal flight under the provisions of the 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed at the time of the accident, and no flight plan was filed. The local flight departed from the Cherry Capital Airport (TVC), Traverse City, Michigan, at 1150.

The pilot reported that the airplane was in cruise flight when the engine started to run rough and vibrate. He adjusted and checked the fuel mixture, throttle, magnetos, boost pump, and carburetor heat, but the vibration continued to get worse. He decided to execute a forced landing to a farmer’s field and touched down with the airplane aligned with the furrows. He reported that the braking was ineffective due to the frozen field, and the airplane impacted a line of trees at the end of the field.

A Federal Aviation Administration airworthiness inspector examined the engine. He determined that the number one and number four cylinders had little to no compression when the propeller was rotated by hand. Both cylinders were removed. The number one cylinder exhaust valve was broken with approximately 50 per cent of the valve face missing. The piston and cylinder head were scarred with impact marks. The number four cylinder’s intact valve and seat were scarred, which was consistent with the compression loss. The upper and lower spark plug electrodes of the number four cylinder were forced closed, and there were impact marks on the piston and cylinder head.

Examination of the airplane’s engine logbooks revealed that the Lycoming O-540-E4B5 engine was overhauled in 1994 by an airframe and powerplant (A&P) mechanic. There was 1,972.3 hours logged on the engine since the last overhaul. There was no indication in the engine logbook that the number one and number four cylinders were repaired or replaced since the engine was overhauled. The most recent annual inspection was completed in April 2011.

The Lycoming Service Instruction No. 1009AT, “Recommended Time Between Overhaul Periods” recommended that the O-540-E4B5 engine be overhauled every 2,000 hours, or after 12 years of service since engine overhaul.

NTSB Probable Cause

The loss of engine power due to the failure of the exhaust valve.