On August 6, 1985, a Hughes 369D (registration N8662F) was involved in an aviation accident near Cheyenne, WY. Investigators recorded the probable cause as: An inflight engine compartment fire that led to an unsuccessful autorotation and substantial damage to the helicopter. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
Aircraft registered N8662F. Photo: Alan Wilson from Stilton, Peterborough, Cambs, UK / CC BY-SA 2.0, via Wikimedia Commons
A helicopter suffered substantial damage after an unsuccessful autorotation caused by an engine compartment fire during a pipeline patrol flight. No injuries were reported.
What happened
The flight was conducted as a pipeline patrol operation. While airborne, smoke was observed entering the cabin from the engine compartment. The pilot attempted an autorotation to land safely but was unable to complete it successfully. This resulted in substantial damage to the helicopter.
The investigation
Post-accident examination revealed that the smoke originated from a fire within the engine compartment during flight.
Findings
The primary factor leading to the accident was an inflight engine compartment fire, which necessitated an emergency landing attempt. The pilot's subsequent autorotation was unsuccessful, causing substantial damage to the aircraft.
Probable cause
An inflight engine compartment fire that led to an unsuccessful autorotation and substantial damage to the helicopter.
