Piper PA-28RT-201 N2878V accident near Gilmer, Texas

Probable cause

The partial loss of engine power due to the loss of cylinder compression. The loss of cylinder compression was the result of the No. 3 piston ring failure due to excessive heat because of the lean fuel mixture from a partially clogged fuel nozzle.

NTSB analysis

The student pilot reported that while he was performing flight maneuvers in preparation for a checkride, the engine backfired and lost partial power. He attempted unsuccessfully to regain engine power. Because he could not maintain altitude and the local terrain was tree-covered, the student pilot chose to ditch the airplane in a nearby lake. A postaccident examination of the engine revealed the No. 3 cylinder lost compression due to the seizure of the No. 3 cylinder piston rings. The No. 3 cylinder fuel nozzle was found partially clogged, which likely resulted in a lean fuel mixture and excessive heat in the cylinder and the subsequent piston ring failure. The reason for the clogged fuel nozzle could not be determined.

Text from the NTSB. Open the NTSB docket for CEN12LA623 for the full record.