On May 11, 1997, a Hughes 369D (registration N5105N) operated by Kaohukaukuahiwi K. Sproat was involved in an aviation accident near Puako, HI. Investigators recorded the probable cause as: erosion of second stage stator vanes, inadequate maintenance inspection for the erosion, and subsequent fatigue failure of a stator vane, which resulted in loss of engine power and a forced landing on mountainous/hilly terrain. This summary draws on records from the U.S. National Transportation Safety Board (NTSB) historical archive.
A helicopter experienced engine failure during low-level cruise. Autorotation with tailwind led to ground impact on upslope. Investigation found forward CG limit exceeded and stator vane fatigue failure.
Sequence of Events
The helicopter was cruising at low level when the engine failed. The pilot turned toward a landing area and entered an autorotation with a quartering tailwind. During the autorotation, the helicopter continued to descend while maintaining a nose low attitude, until it struck the ground. Impact occurred on upsloping terrain, resulting in damage to the helicopter.
Weight and Balance Examination
A computation of the weight and balance revealed that the helicopter's moment arm exceeded the forward center of gravity (CG) limit by approximately one inch. This condition limited the availability of aft cyclic control.
Engine Examination
An examination of the engine determined that a stator vane had failed due to excessive erosion and fatigue cracking. This condition had not been detected during a compressor case erosion inspection conducted 60 flight hours before the accident.
What happened in the 11 May 1997 Hughes 369D accident near Puako, HI?
A helicopter experienced engine failure during low-level cruise. Autorotation with tailwind led to ground impact on upslope. Investigation found forward CG limit exceeded and stator vane fatigue failure.
What aircraft was involved and where did it happen?
The accident on 11 May 1997 involved a Hughes 369D, registration N5105N, operated by Kaohukaukuahiwi K. Sproat, at Puako, HI.
What was the probable cause of the accident?
erosion of second stage stator vanes, inadequate maintenance inspection for the erosion, and subsequent fatigue failure of a stator vane, which resulted in loss of engine power and a forced landing on mountainous/hilly terrain. Also causal was: the pilot's loading of the aircraft in such a manner that exceeded the…
A SkyWalk Join't 3 paraglider crashed into the ground near Las Vizcachas, Chile, on September 1, 2024. The pilot and passenger sustained serious spinal…
PARAPENTE (ULTRALIVIANO NO MOTORIZADO)·2024-09-01DGAC Chile
A Cessna 172N struck electrical cables while on final approach to land at Aucó Aerodrome in Chile. The pilot was uninjured, but the aircraft sustained damage…
A Bombardier DHC-8-402 suffered a tail strike during landing at Puerto Williams on September 9, 2024. All 76 occupants were unharmed, but the aircraft…
A MYD JS-MD 3 glider veered off the runway and struck a wall at Vitacura Aerodrome on January 6, 2025. The pilot was uninjured, but the aircraft sustained…
A recreational paraglider flight in Puchuncaví, Chile, ended with the pilot sustaining serious injuries after a rapid descent and impact with a hillside on…
PARAPENTE (ULTRALIVIANO NO MOTORIZADO)·2025-03-29DGAC Chile
A Tecnam P2006T landed on its belly at an aerodrome in Poland after the crew failed to confirm landing gear deployment. The incident resulted in no injuries…