Luscombe 8A N41907 accident near Dixie, Georgia

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 analysis

The pilot reported that he noted the engine oil temperature rising during cruise flight. He elected to reduce power and fly to the nearest airport. While en route, at an altitude of about 1,000 feet above ground level and a distance of 4 miles, the engine experienced a catastrophic failure. The pilot landed the airplane on an open field; however, he could not stop the airplane on the remaining surface and it impacted two trees in a wooded area beyond the field.

A postaccident 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 the piston connecting rod bearings and their respective bolts and nuts were replaced. Thus, it is 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.

Text from the NTSB. Open the NTSB docket for ERA12FA017 for the full record.