This May 2007 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.
Location: Tuscon, Ariz.
Aircraft damage: Minor.
What reportedly happened: The airplane was in cruise flight about 1,600 feet above ground when the engine began losing power. The airplane was less than a half mile from the destination airport. The pilot attempted to restore engine power but was unsuccessful. He attempted to glide to the airport but lacked sufficient altitude to reach the airport and the airplane came down in rough terrain about a third of a mile from the runway.
During the subsequent examination of the engine, the top surface of the number three piston was observed to be damaged, and the cylinder’s exhaust valve head was broken off from the stem.
Probable cause: A loss of engine power while maneuvering due to a broken exhaust valve.
For more information: NTSB.gov/ntsb/brief2.asp?ev_id=20070515X00567&ntsbno=LAX07LA153&akey=1.