This December 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 Arrow. Location: Augusta, Ga. Injuries: 1 Fatal. Aircraft damage: Destroyed.
What reportedly happened: The airplane was in cruise flight when the engine began to run rough. The 160-hour private pilot contacted ATC and was given vectors to the nearest airport. He subsequently reported that the engine had lost power and that he could not make it to the airport so he would attempt to land on a road. The airplane touched down in a parking lot and continued to travel for about 50 feet, until it hit a building and caught fire. A witness reported that the engine sounded as if “all the cylinders weren’t firing.” Examination of the engine revealed that the number two cylinder was displaced from the crankcase and the associated connecting rod was separated from the crankshaft. Examination of the studs used to attach the cylinder to the crankcase revealed fatigue fractures.
There was also mechanical damage inside of the crankcase. According to maintenance records, 22 months before the accident the engine case had a crack in it. The crack was repaired and the airplane returned to service. The most recent 100-hour inspection was performed one month before the accident and no anomalies were noted. At that time, the engine had accumulated 1,409 hours since major overhaul. The investigator could not determine if a specific maintenance action allowed the fatigue crack.
Probable cause: A loss of engine power due to the fatigue fracture of the number two cylinder attach studs, and the subsequent separation of the number two cylinder.
For more information: NTSB.gov