NTSB Identification: ERA12LA366
14 CFR Part 91: General Aviation
Accident occurred Friday, May 25, 2012 in Longboat Key, FL
Probable Cause Approval Date: 01/13/2014
Aircraft: BELL 206B, registration: N806LA
Injuries: 4 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 reported that, while in cruise flight at an altitude of about 500 feet above ground level, the helicopter experienced a total loss of engine power. According to the pilot, the initial indication was a slight yaw, which was followed by the engine-out warning horn. He immediately lowered the collective and entered a power-off autorotation to land on the beach. Upon touchdown, the helicopter's skids dug into the soft sand, and the main rotor blades contacted the tail boom, damaging the drive shaft cover and severing the tail rotor drive shaft. Examination of the helicopter’s structure and systems showed no evidence of failure or malfunction. Attempts to start the engine in a test cell were unsuccessful until the fuel pump was replaced, after which the engine started and operated within all specifications.
Examination of the removed fuel pump indicated that the main drive shaft splines and the internal drive gear splines were worn to the point of no spline engagement, which resulted in a loss of fuel pump flow.
The engine manufacturer, Rolls-Royce (formerly Allison), issued commercial engine bulletin (CEB) A-1352 on August 21, 1997, which recommended inspection of the fuel pump splines at 100-hour intervals, beginning within 25 hours of receipt of the bulletin. The 100-hour interval spline inspections were an interim safeguard while product improvements were developed and validated. On April 30, 1998, Rolls-Royce (Allison) issued CEB 1355, which recommended a fuel pump upgrade no later than March 31, 1999. Upon compliance with upgrade bulletin, the 100-hour spline inspections indicated by CEB A-1352 were no longer required. Although it was not possible to determine whether the 100-hour spline inspections recommended in CEB A-1352 had been accomplished, the model number of the accident helicopter’s fuel pump indicated that the fuel pump upgrade recommended by CEB A-1355 had not been completed. If the fuel pump upgrade had been completed in accordance with the manufacturer’s guidance, the accident helicopter’s fuel pump would not have failed as it did.
The National Transportation Safety Board determines the probable cause(s) of this accident to be: Unknown personnel's failure to comply with the engine manufacturer's engine fuel pump replacement guidance, which resulted in a total loss of engine power due to the engine fuel pump failure. Full narrative available
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