On June 29, 2006, a Mooney M20J (registration N5662M) was involved in an aviation accident near Beaumont, TX. Investigators recorded the probable cause as: Improper propeller governor installation which allowed engine oil to vent overboard, resulting in oil starvation and failure of a number four piston to crankshaft connecting rod cap bolt, leading to the connecting rod being forced through the engine crankcase… This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 8 related events involving the same aircraft type or operator are linked below.
During initial climb, the engine experienced RPM fluctuation and internal failure. The pilot shut down and performed a forced landing to a field, striking a fence. Investigation found improper propeller governor installation caused oil starvation and connecting rod failure.
Accident Summary
The private pilot, with 257 hours of flight experience, was conducting an initial climb after takeoff when the airplane's propeller RPM began to fluctuate uncommanded. Subsequently, an internal failure of the engine occurred. Although the engine continued to run, it emitted smoke and shook violently. The pilot elected to shut down the engine and perform a landing to a grassy field. During the landing roll, the airplane impacted a barbwire fence.
Engine Examination
A teardown examination of the engine was performed. The examination revealed that the propeller governor was installed contrary to the engine manufacturer's Parts Catalog and Service Instructions. This improper installation allowed engine oil to vent overboard, resulting in oil starvation. The oil starvation caused the failure of a number four piston to crankshaft connecting rod cap bolt. Subsequently, the number four connecting rod was forced through the engine crankcase, leading to a loss of engine power.
Probable cause
Improper propeller governor installation which allowed engine oil to vent overboard, resulting in oil starvation and failure of a number four piston to crankshaft connecting rod cap bolt, leading to the connecting rod being forced through the engine crankcase and loss of engine power.