On July 24, 1993, a Hughes 369D (registration N3115Y) operated by Soloy Helicopters, Inc. was involved in an aviation accident near Cordova, AK. Investigators recorded the probable cause as: A LOSS OF ENGINE POWER FOR UNDETERMINED REASONS. A FACTOR WAS THE ROUGH/UNEVEN TERRAIN. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive; 1 related events involving the same aircraft type or operator are linked below.
A helicopter experienced a partial loss of engine power while hovering near a mountainside, causing it to settle backward and strike the ground with its tail.
What happened
The incident occurred while the helicopter was maintaining a hover position adjacent to a steep terrain feature. The aircraft was positioned with only the forward portion of the skids in contact with or extremely close to an approximate 45-degree slope of a mountain. During this phase of flight, both the pilot and a passenger reported hearing and feeling a distinct thump associated with the external load.
Immediately following this event, the helicopter lost its ability to maintain altitude and settled backward. The descent continued until the tail section of the aircraft came to rest on the ground surface. The pilot subsequently stated that he had experienced a partial loss of engine power at the time of the incident, which prevented him from sustaining the hover.
The investigation
Following the accident, maintenance personnel conducted tests on the helicopter's engine using a test stand. These bench tests indicated that the engine operated normally and did not exhibit any mechanical faults or performance issues during the evaluation. Despite these normal findings, the specific cause of the power loss experienced by the pilot during the hover was not determined.
Findings
The helicopter settled backward while hovering near a steep mountainside.
The tail of the aircraft struck the ground upon descent.
The pilot reported a partial loss of engine power prior to the settlement.
Post-accident engine testing on a stand showed normal operation.
The cause of the in-flight power loss was not determined.