Aircraft: Luscombe 8A. Injuries: 1 Fatal, 1 Serious. Location: Dixie, Ga. Aircraft damage: Substantial.
What reportedly happened: While the airplane was in cruise flight, the pilot noticed the engine oil temperature rising.
He reduced power and headed toward the nearest airport. The airplane was four miles from the destination at an altitude of about 1,000 feet AGL when the engine experienced a catastrophic failure. The airplane collided with two trees during the forced landing.
The post-accident examination revealed that the No. 2 cylinder piston connecting rod had separated from the crankshaft. One of the bolts securing the rod cap was missing. The bolt and nut were recovered from internal engine debris, however a safety cotter pin necessary to secure the bolt was not located.
About 20 engine-operating hours before the accident, all of the engine’s piston connecting rod bearings and their respective bolts and nuts had been replaced. Investigators determined that it was likely that at that time one of the two nuts was not properly secured with a cotter pin on the No. 2 cylinder piston connecting rod, allowing the nuts to slowly unthread over time.
Probable cause: Maintenance personnel’s improper installation of the No. 2 cylinder’s connecting rod, which resulted in the disconnection of the rod and a subsequent loss of engine power.
NTSB Identification: ERA12FA017
This October 2011 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.