NTSB Identification: CEN12IA096
Nonscheduled 14 CFR Part 135: Air Taxi & Commuter
Incident occurred Thursday, December 01, 2011 in Gulf Of Mexico, GM
Probable Cause Approval Date: 04/10/2013
Aircraft: BELL HELICOPTER TEXTRON CANADA 407, registration: N435PH
Injuries: 2 Uninjured.
NTSB investigators used data provided by various sources and may not have traveled in support of this investigation to prepare this aircraft incident report.
While maneuvering for a precautionary landing to an oil rig platform because of a chip light indication, the helicopter's engine lost power. The pilot entered an autorotation, called mayday, inflated the helicopter’s floats, and performed a successful water landing. The pilot and passenger were able to exit the helicopter unassisted into a life raft and were picked up within 10 minutes. Examination and disassembly of the engine revealed the No. 2 bearing had failed. Metallurgical examination of the bearing showed the No. 2 bearing outer ring cracked in fatigue due to false brinnelling, which occurs in cases where the bearing is stationary but is subjected to ambient vibration or shock during transport. A spalling area was severe enough to propagate mechanical stress in the outer ring causing the ring to fracture. The engine compressor section was overhauled 2.7 hours before the failure.
The National Transportation Safety Board determines the probable cause(s) of this incident to be: The failure of the compressor section No. 2 bearing due to false brinnelling and fatigue. Full narrative available
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