On June 11, 1987, a Boeing 737-200 (registration N782N) operated by Piedmont Aviation,inc. was involved in an aviation accident near Columbus, OH. Investigators recorded the probable cause as: The right air conditioning air cycle machine leaked oil into the heat exchanger due to a nicked oil slinger ring, causing turbine oil to overheat and produce smoke. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 3 related events involving the same aircraft type or operator are linked below.
Photo: San Diego Air & Space Museum Archives / Public domain, via Wikimedia Commons
A flight attendant reported smoke and a pungent odor in the cabin, which dissipated then returned during descent, leading to a precautionary landing. Examination found a nicked oil slinger ring caused an air cycle machine oil leak, overheating turbine oil.
Incident Overview
A flight attendant reported smoke and a pungent odor in the cabin. The smoke and odor initially dissipated but returned after the aircraft began its descent for landing. Passengers informed the flight crew of the smoke intensity, prompting a precautionary landing at a divert field.
Examination Findings
Subsequent examination revealed that the right air conditioning air cycle machine had leaked oil into the heat exchanger. The leak was attributed to a nicked oil slinger ring within the machine. The leaked turbine oil overheated in the heat exchanger, producing the smoke observed in the cabin.
Probable cause
The right air conditioning air cycle machine leaked oil into the heat exchanger due to a nicked oil slinger ring, causing turbine oil to overheat and produce smoke.
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