NTSB Identification: NYC01LA059.
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Accident occurred Monday, December 18, 2000 in West Mifflin, PA
Probable Cause Approval Date: 05/30/2003
Aircraft: Aerospatiale SA365-N1, registration: N89SM
Injuries: 2 Serious,1 Uninjured.
NTSB investigators may not have traveled in support of this investigation and used data provided by various sources to prepare this aircraft accident report.
The pilot stated he that performed a pre-flight inspection, checked the fluids, and ensured that the cowlings were closed and secured prior to conducting the helicopter's post-maintenance track and balance flight. In flight, after conducting several maneuvers, and while the helicopter was flying straight and level at 120 knots, the pilot noticed he had no anti-torque pedal control. He declared an emergency, and attempted numerous approaches to two different runways. Every time the helicopter slowed to 80-100 knots, the nose would swing to the left. During the final approach, while nearing touchdown on the runway, the pilot added collective, and the helicopter climbed while spinning to the left. The pilot reduced power, and the helicopter descended to, and impacted the ground while still in a left spin. Post-accident examination revealed that the bellcrank fitting at the tail servo input was broken, and there was very little oil in the tail rotor gearbox. There was no evidence of oil leakage at the seals or the filler cap. A small amount of oil was recovered, which was black in appearance. The oil level sight gage was marked with a black line, 6 to 7 mm below the minimum fill level. The output drive shaft duplex bearing displayed no evidence of lubrication. The inner races of the duplex bearing were removed and one displayed signs of wear and heat damage. The outer races contained metal transfers similar to the bearing cage, and the duplex bearing was seized. The flight manual did not contain any emergency procedures for a stuck (fixed pitch) tail rotor.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: Insufficient lubrication within the tail rotor gearbox, which resulted in the seizure of the duplex ball bearing and a fixed pitch setting of the tail rotor. Also causal, was the pilot's loss of control, which was the result of a relative low speed/high power combination during a go-around attempt. A factor was the manufacturer's lack of procedures for fixed tail rotor pitch settings. Full narrative available
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