Piper PA-28-140 N15037 accident near Allentown, Pennsylvania

Probable cause

The operator's failure to perform magneto inspections per the manufacturer's recommendations and failure to comply with the engine manufacturer's recommended time interval for engine overhaul, which resulted in defects in the magnetos going undetected and the failure of the right magneto during initial climb.

NTSB analysis

During the initial climb, the engine lost partial power, and the flight instructor performed a forced landing into a cornfield. During a subsequent test-run of the engine, the engine would lose all power if only the right magneto was selected. Laboratory examination of the right magneto revealed that seven teeth from its drive gear were fractured and exhibited single-sided bending fatigue, consistent with applied force in one direction over a period of time. At the time of the accident, the engine had accumulated about 2,300 hours since overhaul, which had been completed about 7 years prior. The accident magnetos had not been replaced or serviced since they were installed during engine overhaul. The engine manufacturer recommended overhauling the engine every 2,000 hours or 12 years, which would have included replacing the magnetos with new or overhauled units. Additionally, a service bulletin issued by the magneto manufacturer recommended inspecting the magnetos every 500 hours; however, there was no evidence that an inspection was ever performed during the 2,300-hour life of the failed magneto.

Text from the NTSB. Open the NTSB docket for ERA13LA025 for the full record.