Accident Hughes 369D N911FT,
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ASN Wikibase Occurrence # 285026
 
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Date:Thursday 19 April 2007
Time:13:05 LT
Type:Silhouette image of generic H500 model; specific model in this crash may look slightly different    
Hughes 369D
Owner/operator:
Registration: N911FT
MSN: 811036D
Year of manufacture:1981
Total airframe hrs:14899 hours
Engine model:Rolls-Royce 250-C20B
Fatalities:Fatalities: 0 / Occupants: 4
Aircraft damage: Substantial
Category:Accident
Location:Kahuku, Oahu, HI -   United States of America
Phase: Unknown
Nature:Unknown
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
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.

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.

Accident investigation:
cover
  
Investigating agency: NTSB
Report number: SEA07LA108
Status: Investigation completed
Duration: 1 year
Download report: Final report

Sources:

NTSB SEA07LA108

Revision history:

Date/timeContributorUpdates
01-Oct-2022 16:47 ASN Update Bot Added
12-Jun-2023 03:49 Ron Averes Updated

Corrections or additions? ... Edit this accident description

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