Piper PA-22-160 N8119D accident near Kenai, Alaska

Probable cause

Improper installation of the crankshaft drive gear by maintenance personnel, who failed to install all required hardware, resulting in an in-flight engine failure.

NTSB analysis

Shortly after takeoff, the engine lost power and the propellor began to windmill. The flight instructor conducted emergency procedures but was unable to regain engine power. The flight instructor determined that they did not have sufficient altitude to make it back to the airport and he selected a road on which to make a forced landing. To avoid a car, the pilot turned slightly towards the edge of the road and was pulled into a snow berm, where the aircraft came to a full stop. The airplane sustained substantial damage to the right wing and fuselage.

A postaccident examination of the engine found the crankshaft drive gear bolt was missing and the gear alignment dowel pin on the crankshaft was broken. The missing bolt was not found during the postaccident examination. The engine was last disassembled in 1983 and the accessory gearbox was opened for an oil pump rebuild in 2006; the investigation was not able to identify how long the engine had operated with the bolt missing. The crankshaft drive gear drives the accessory gear box and, according to the engine manufacturer, failure of the gear or the gear attaching parts would result in complete engine stoppage.

Text from the NTSB. Open the NTSB docket for ANC23LA005 for the full record.