Cessna 177RG N7542V accident near Crestview, Florida

Probable cause

The total loss of engine power due to the loosening and separation of the No. 1 connecting rod cap nuts in flight, resulting in catastrophic internal engine damage. Contributing to the accident was the pilot/owner’s failure to comply with the engine manufacturer’s service instruction on engine overhaul intervals.

NTSB analysis

The pilot reported that, during a flight in visual conditions, he heard a “boom” from the propeller hub. The propeller immediately began to oscillate and shudder violently, accompanied by severe engine vibration and oil loss. He shut the engine down and executed a forced landing to a field that resulted in structural damage to the airplane. The pilot sustained serious injuries.

A teardown examination of the engine after recovery of the wreckage revealed that the No. 1 connecting rod cap separated from the rod during flight, resulting in catastrophic engine damage. Damage to the rod cap bolts and nuts was consistent with the nuts loosening and backing out over time. There was no evidence of heat distress on the affected parts.

A review of the aircraft maintenance logbooks revealed that the last overhaul of the engine was performed more than 30 years before the accident. A service instruction issued by the engine manufacturer instructs all engine models to be overhauled within twelve calendar years of the date they first entered service or of the last overhaul.

Text from the NTSB. Open the NTSB docket for ERA23LA197 for the full record.