ASN Wikibase Occurrence # 285026
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Narrative:During an aerial surveillance flight, the helicopter's engine chip light illuminated, and the pilot headed towards a nearby heliport to make a precautionary landing. The pilot established a steep fast approach in case of engine failure while on approach. At approximately 100 feet above the ground and an airspeed of 65 knots, he applied power and began to slow the helicopter. At this point, the engine lost power, and the pilot entered an autorotation. The helicopter landed hard breaking both forward landing gear struts and spreading the rear struts. The main rotor blades impacted the tail boom, and the tail boom separated from the fuselage. Examination of the helicopter revealed heavy deposits of oil on the inner surfaces of the engine compartment as well as on the exterior surfaces of the engine. There was no oil in the airframe engine oil reservoir. The oil line leading from the engine gearbox to the oil pressure gauge was found cracked beneath the "B" nut securing it to the fitting on the engine gearbox. The N2 (power turbine) drive could not be rotated. Partial disassembly of the engine revealed damage to the number six, seven, and eight bearings consistent with a lack of adequate lubrication. Laboratory examination of the cracked oil line found fatigue cracking had propagated through an estimated 90 percent of the cross-sectional area of the tube. The cracking allowed lubricating oil to leak from the line resulting in oil starvation to the bearings leading to seizure of the power turbine.
|Fatalities:||Fatalities: 0 / Occupants: 4|
|Aircraft damage:|| Substantial|
|Location:||Kahuku, Hawaii -
United States of America
|Departure airport:||Honolulu-Daniel K. Inouye International Airport, HI (HNL/PHNL)|
|Destination airport:||Kahuku, HI (HI58)|
|Investigating agency: ||NTSB|
|Confidence Rating:|| Accident investigation report completed and information captured|
Probable Cause: Fatigue cracking of the oil line from the engine gearbox to the oil pressure gauge, which resulted in loss of engine lubricating oil, leading to seizure of the power turbine.
| || |
|Investigating agency: ||NTSB |
|Status: ||Investigation completed|
|Duration: ||1 year |
|Download report: || Final report|
||ASN Update Bot
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