On October 5, 1996, a Cessna 150H (registration N6741S) was involved in an aviation accident near Sunbury, PA. Investigators recorded the probable cause as: The failure of one of the four bolts holding the crankshaft cluster gear to the crankshaft, which failed due to fatigue in the threaded area. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A pilot experienced an engine power loss at 2,200 ft MSL. Restart attempts failed, leading to a forced landing. Post-accident examination revealed four failed bolts securing the crankshaft cluster gear, with one bolt showing fatigue failure.
Incident Summary
A pilot reported that the engine lost power while the aircraft was climbing through 2,200 feet above mean sea level (MSL). The pilot stated that attempts to restart the engine using emergency procedures were unsuccessful. During a forced landing in a field, the airplane struck a rock and nosed over.
Post-Accident Examination
Following the accident, an FAA inspector examined the airplane. The inspection found that the four bolts securing the crankshaft cluster gear to the crankshaft had failed. When the accessory gear box cover was removed, the cluster gear rotated freely. Examination of the four bolts revealed that one of the bolts failed due to fatigue in the threaded area. The failure mode of the other three bolts could not be determined because of smearing.
Engine History
The engine had accumulated over 356 hours since its last overhaul. The pilot stated that he was unsure why the prior owner had the engine overhauled.
Probable cause
The failure of one of the four bolts holding the crankshaft cluster gear to the crankshaft, which failed due to fatigue in the threaded area.
What happened in the 5 Oct 1996 Cessna 150H accident near Sunbury, PA?
A pilot experienced an engine power loss at 2,200 ft MSL. Restart attempts failed, leading to a forced landing. Post-accident examination revealed four failed bolts securing the crankshaft cluster gear, with one bolt showing fatigue failure.
What aircraft was involved and where did it happen?
The accident on 5 Oct 1996 involved a Cessna 150H, registration N6741S, at Sunbury, PA.
What was the probable cause of the accident?
The failure of one of the four bolts holding the crankshaft cluster gear to the crankshaft, which failed due to fatigue in the threaded area.
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