On August 20, 1986, a Cessna 182N (registration N92252) was involved in an aviation accident near Wilmington, CA. Investigators recorded the probable cause as: Over-torquing of the rocker arm shaft keeper bolt during overhaul, resulting in failure of the number one cylinder exhaust valve rocker arm shaft boss journal. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a night instructional flight, the engine ran rough and quit. The aircraft struck power lines and buildings during a forced landing. Investigation revealed a failed cylinder exhaust valve component due to an over-torqued bolt during overhaul.
Incident Summary
During a local night instructional flight, the pilots reported that the engine began to run very rough and eventually quit when power was reduced slightly to begin the descent for the destination airport. The aircraft subsequently struck power lines, two small buildings, and a brick wall during a forced landing in an industrial area.
Investigation Findings
Examination of the engine revealed that the number one cylinder exhaust valve rocker arm shaft boss journal had failed. Tests conducted on an identical engine in a test cell, duplicating the boss journal failure, replicated the power loss described by the crew. The cylinder had been changed 27 hours prior to the accident. Evidence indicated that the rocker arm shaft keeper bolt had been over-torqued during the overhaul.
Probable cause
Over-torquing of the rocker arm shaft keeper bolt during overhaul, resulting in failure of the number one cylinder exhaust valve rocker arm shaft boss journal.
What happened in the 20 Aug 1986 Cessna 182N accident near Wilmington, CA?
During a night instructional flight, the engine ran rough and quit. The aircraft struck power lines and buildings during a forced landing. Investigation revealed a failed cylinder exhaust valve component due to an over-torqued bolt during overhaul.
What aircraft was involved and where did it happen?
The accident on 20 Aug 1986 involved a Cessna 182N, registration N92252, at Wilmington, CA.
What was the probable cause of the accident?
Over-torquing of the rocker arm shaft keeper bolt during overhaul, resulting in failure of the number one cylinder exhaust valve rocker arm shaft boss journal.
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