On May 5, 1991, a Hughes 369HS (registration N9219F) operated by Gerardin Corp. was involved in an aviation accident near Keanae, HI. Investigators recorded the probable cause as: THE TOTAL FAILURE IN FATIGUE OF THE HELICOPTER'S SPUR ADAPTER GEARSHAFT. A CONTRIBUTING FACTOR WAS RELATED TO THE LACK OF A SUITABLE EMERGENCY LANDING SITE. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During an air taxi sightseeing flight, the pilot experienced a sudden total loss of engine power, resulting in a forced landing with tree collision. Investigation revealed fatigue failure of the forward splines on the spur adapter gearshaft, disconnecting the SAG from the drive system.
Event Description
During an air taxi sightseeing flight, the pilot encountered a sudden total loss of all engine power. The pilot executed a forced landing, during which the helicopter collided with trees.
Engine Examination
Post-accident examination of the helicopter's engine revealed that the forward splines on the spur adapter gearshaft had failed due to fatigue. This failure caused the spur adapter gear (SAG) to become disconnected from the drive system. A metallurgical examination of the failed SAG determined that it conformed to the manufacturer's design specifications.
Maintenance History
The compressor and the SAG had undergone an overhaul 826.8 operational hours before the accident. No further details about the maintenance were provided.
What happened in the 5 May 1991 Hughes 369HS accident near Keanae, HI?
During an air taxi sightseeing flight, the pilot experienced a sudden total loss of engine power, resulting in a forced landing with tree collision. Investigation revealed fatigue failure of the forward splines on the spur adapter gearshaft, disconnecting the SAG from the drive system.
What aircraft was involved and where did it happen?
The accident on 5 May 1991 involved a Hughes 369HS, registration N9219F, operated by Gerardin Corp., at Keanae, HI.
What was the probable cause of the accident?
THE TOTAL FAILURE IN FATIGUE OF THE HELICOPTER'S SPUR ADAPTER GEARSHAFT. A CONTRIBUTING FACTOR WAS RELATED TO THE LACK OF A SUITABLE EMERGENCY LANDING SITE.
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