On December 12, 1988, a Hughes 369E (registration N7733H) operated by Kauai Helicopter was involved in an aviation accident near Hanalei, HI. Investigators recorded the probable cause as: The gas generator turbine failed due to constant turbine overtemperatures. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a sightseeing flight, a helicopter experienced a turbine failure and forced landing on a beach, resulting in a nose-over. Investigation found overtemperature due to faulty exhaust probe and improper fuel flow setting.
Incident Summary
During a local sightseeing flight, the pilot reported hearing a muffled bang, followed immediately by the activation of engine out warning lights and an audio alarm. The pilot initiated a forced landing on a beach. During the landing, the helicopter nosed over.
Examination Findings
An examination of the engine revealed that the gas generator turbine had failed. Evidence indicated that the failure was due to constant turbine overtemperatures. Subsequent testing of the exhaust temperature probe system showed that it provided readings 50 to 100 degrees lower than the actual temperature. Additionally, the lightoff fuel flow was found to be excessive because of the improper setting of the start/accelerator schedule adjuster.
Maintenance Records
Review of the maintenance records did not indicate a recent exhaust temperature check.
Probable cause
The gas generator turbine failed due to constant turbine overtemperatures.