On June 22, 1986, a Piper J3C (registration N3667K) was involved in an aviation accident near Kent, WA. Investigators recorded the probable cause as: A broken crankshaft, which caused a total loss of power and necessitated a forced landing on rough terrain. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
An aircraft experienced a total loss of power, resulting in a forced landing on rough rising terrain where the left main gear collapsed. Investigation revealed a broken crankshaft.
What happened
The pilot executed a forced landing following a complete loss of engine power. The aircraft was landed onto very rough, rising terrain. During the landing roll, the left main landing gear collapsed.
The investigation
A post-accident examination revealed that the engine crankshaft had broken. Records indicated that a top overhaul had been performed less than 30 hours prior to the incident, and a major overhaul had been completed less than 300 hours before the event.
Findings
The mechanical failure of the crankshaft was the primary factor leading to the power loss. The rough terrain contributed to the collapse of the landing gear during the roll.
Probable cause
A broken crankshaft, which caused a total loss of power and necessitated a forced landing on rough terrain.