Cessna 172M N5177H accident near Friend, Nebraska

Probable cause

A loss of engine power due to a stuck valve.

NTSB analysis

The pilot stated that he noticed a slight hesitation in the engine, followed by backfiring and a large drop in engine speed while in cruise flight at 2,000 ft above ground level. He was able to regain partial power for a few minutes before the engine lost additional power. The pilot performed a forced landing between two corn fields, where the airplane sustained substantial damage to the fuselage due to impact with terrain.

Postaccident testing of the engine revealed a stuck exhaust valve on the No. 2 cylinder that resulted in the loss of engine power during cruise flight. No other anomalies were noted with the engine or related systems that would have precluded normal operations of the engine. Thus, the stuck exhaust valve likely resulted in the partial loss of engine power.

Text from the NTSB. Open the NTSB docket for CEN22LA309 for the full record.