This April 2009 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.
Aircraft: Piper Cherokee. Injuries: None. Location: Hilliard, Fla. Aircraft damage: Substantial.
What reportedly happened: The pilot had recently purchased the airplane. The seller reported that an oil leak was noted during the “pre-buy” inspection. The mechanic who inspected the airplane at the pre-buy reported that two cylinders were leaking oil. The seller installed the cylinders as part of a major overhaul that occurred approximately 131 hours before the accident. The pilot who bought the airplane did not have maintenance performed to address the cylinder oil leaks. Approximately two hours into the cross-country flight the pilot heard a loud noise from the engine compartment and the engine subsequently failed. The pilot performed a forced landing in a field.
Examination of the engine revealed that the No. 3 cylinder partially separated in flight, resulting in the engine failure. An engine cylinder attachment stud and nut were found at the run-up pad at the departure airport. Examination of the stud revealed evidence of fatigue cracking, which was indicative of an under torque condition. Other cylinder attachment nuts on the engine showed evidence of under torquing.
Probable cause: A total loss of engine power due to the fatigue failure of the No. 3 cylinder attachment stud as a result of insufficient torque during installation. Contributing to the accident was the pilot’s operation of the airplane with a known mechanical deficiency.
For more information: NTSB.gov