On March 11, 1991, a Hughes 369D (registration N1088L) operated by Gregory Forest Products was involved in an aviation accident near Roseburg, OR. Investigators recorded the probable cause as: A LOSS OF ENGINE POWER FOR UNDETERMINED REASONS. A FACTOR RELATED TO THE ACCIDENT WAS: THE LACK OF A SUITABLE AREA FOR AN EMERGENCY LANDING. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A Hughes 369D helicopter experienced a sudden engine power loss during cruise, leading to an autorotation landing on a sloped highway. The right skid dropped after touchdown, causing the main rotor blades to strike the tailboom.
Pilot Report
The pilot of a Hughes 369D reported that the helicopter was cruising at an altitude between 300 and 500 feet above the surface. He heard a loud 'pop' and then the engine spooled down rapidly. According to the pilot, there was no prior indication of a problem until the engine abruptly lost power.
Autorotation and Landing
Upon the loss of engine power, the pilot initiated an autorotation and landed on a sloped portion of a highway. After touchdown, the right skid dropped approximately 20 inches, causing the main rotor blades to strike the tailboom.
Post-Accident Examination
No preimpact mechanical discrepancy was found during the examination of the helicopter. The engine and other components did not exhibit any failure or malfunction that could have caused the power loss.