On May 6, 1982, a Hughes 369HS (registration N9184F) operated by Thomas Heli was involved in an aviation accident near Gooding, ID. Investigators recorded the probable cause as: Fatigue failure of the spur adapter gearshaft, which initiated on the loaded side of a spline tooth at an area of heavy wear. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
During a turn, the pilot heard a bang and lost engine power. An autorotative landing from low altitude resulted in a hard landing and rollover. Investigation found fatigue failure of the spur adapter gearshaft.
Incident
While executing a turn at the end of a swath run, the pilot heard a distinct bang and subsequently noticed a loss of engine power. The pilot entered an autorotative landing from a low altitude at a low airspeed. The helicopter then landed hard and rolled over onto its right side.
Investigation
An investigation into the incident revealed that the spur adapter gearshaft had failed due to fatigue. The fatigue crack originated on the loaded side of a spline tooth at an area of heavy wear. The total flight time accumulated on the failed part was 3491 hours. The spur adapter gearshaft serves to couple the compressor to the N1 turbine.
Findings
The failure of the spur adapter gearshaft led to the loss of engine power. The subsequent autorotative landing from a low altitude and low airspeed resulted in a hard landing and rollover. No other factors were identified in the investigation.
Probable cause
Fatigue failure of the spur adapter gearshaft, which initiated on the loaded side of a spline tooth at an area of heavy wear.
