Longboat Key, FL, USA
N806LA
BELL 206B
While enroute at 500 feet above ground level, the pilot experienced a total loss of engine of engine power. According to the pilot, the initial indication was a slight yaw followed by the engine out warning horn. He immediately lowered the collective and entered a power-off autorotational landing to the beach. Upon touch down, the helicopter's skids dug into the soft sand and the main rotor blades contacted the tail boom causing damage to the drive shaft cover and severing the tail rotor drive shaft. The pilot and passengers exited the helicopter as soon as the main rotor stopped. Examination of the helicopter structure and systems showed no evidence of failure or malfunction. The engine was removed from the helicopter and placed in a test cell. Attempts to start the engine were unsuccessful and the fuel put was determined to be inoperative. The fuel pump was replaced and the engine started and operated within all specifications. Examination of the engine fuel pump determined the main drive shaft splines and the internal drive gear splines were worn away to the point of no spline engagement. This model of fuel pump was required to have spline inspections every 100 hours, and ultimately required upgrade as a result of spline wear observed on some pumps. Rolls-Royce (formerly Allison) commercial engine bulletin CEB A-1352, dated August 21, 1997, required 100-hour spline inspections with compliance within 25 hours of receipt of bulletin. Spline inspections were an interim safeguard while product improvements were developed and validated. Rolls-Royce (Allison) commercial engine bulletin CEB 1355, dated April 30, 1998 required pump upgrade with compliance no later than March 31, 1999. Upon compliance with upgrade bulletin, spline inspections mandated by CEB A-1352 were no longer required. The model number of the fuel pump installed indicated that the required upgrade had not been completed. Had the inspections and upgrade been completed, the pump would not have failed in the manner it did.
On May 25, 2012, about 1425 eastern daylight time, a Bell 206B, N806LA, registered to and operated by Aircraft Holdings and Leasing LLC, was substantially damaged during landing following a loss of engine power near Longboat Key, Florida. The airline transport pilot and three passengers were not injured. Visual meteorological conditions prevailed and no flight plan was filed for the personal flight which was conducted under the provisions of 14 Code of Federal Regulations Part 91. The flight departed Ruskin, Florida, and was enroute to Sarasota, Florida. While enroute at 500 feet above ground level, near Longboat Key, Florida, the flight experienced a total loss of engine power. According to the pilot, the initial indication was a slight yaw followed by the engine out warning horn. He immediately lowered the collective and entered a power-off autorotational landing to the beach. Upon touch down, the helicopter's skids dug into the soft sand and the main rotor blades contacted the tail boom causing damage to the drive shaft cover and severing the tail rotor drive shaft. The pilot and passengers exited the helicopter as soon as the main rotor stopped. An examination of the helicopter, with oversight provided by Federal Aviation Administration (FAA) inspectors, was conducted. The helicopter was positioned upright on its landing skids with the main rotor head and blades removed to facilitate transport. The damage to the airframe consisted of main rotor impact damage to the top of the tail boom approximately midspan severing the tail rotor drive shaft. Slight skin wrinkling was visible on the right side of the tail boom, at and just forward of the tail boom attaching point. The airframe fuel filter was removed and examined. The filter bowl contained fuel which appeared normal in color and odor. Some light debris was observed in the bottom of the bowl. The helicopter was defueled using the helicopter boost pumps where approximately 33 gallons of fuel were off loaded. The boost pumps were then removed and visually examined with no blockage or anomalies noted. The engine remained securely attached to the airframe with no visible damage noted. Engine fuel, pneumatic, and oil lines were checked visually and tactilely with no damage observed and with all "B" nuts and connectors at least finger tight. The N1 drive train was found to be rotationally free and continuous from the starter generator pad to the compressor during manual rotation. The N2 drive train was found free, smooth, and continuous from the #4 power turbine wheel to the power take-off pad. Both upper and lower chip detectors were removed and examined and only light fuzz was observed on the detectors. The engine was removed from the helicopter and shipped to the manufacturer's facility for testing with FAA oversight. The engine was mounted in a test cell. Attempts were made to start the engine which proved unsuccessful. Fuel was noted at each point throughout the fuel system with the exception of the output port on the fuel control unit. The fuel pump was removed and examined. The pump driveshaft remained visually intact however the shaft could be manually rotated and the pumps internal gearing made a growling sound when rotated. The fuel pump was replaced with a known serviceable original equipment manufacturer (OEM) fuel pump and the engine then started normally within specification time and temperature. Testing of the engine was then conducted in accordance with Rolls-Royce PTS 788 where timed accelerations and decelerations, governor droop checks, and maximum take-off power where all found to meet specification. The fuel pump was examined at Goodrich Pump and Engine Controls with FAA oversight. Disassembly inspection of the pump revealed both the main drive shaft splines and the internal drive gear splines to have worn away to the point of no spline engagement. No other anomalies were discovered during the inspection. Examination also determined the pump to not be in compliance with current Commercial Engine Bulletins for this model pump. This model of fuel pump was required to have spline inspections every 100 hours, and ultimately required upgrade as a result of spline wear observed on some MFP-263 pumps. Rolls-Royce (formerly Allison) commercial engine bulletin CEB A-1352, dated August 21, 1997, required 100-hour spline inspections with compliance within 25 hours of receipt of bulletin. Spline inspections were an interim safeguard while product improvements were developed and validated. Rolls-Royce (Allison) commercial engine bulletin CEB 1355, dated April 30, 1998 required pump upgrade with compliance no later than March 31, 1999. Upon compliance with upgrade bulletin, spline inspections mandated by CEB A-1352 were no longer required. The model number of the fuel pump installed indicated that the required upgrade had not been completed. According to FAA records, the pilot held an airline transport pilot and flight instructor certificates, with ratings for airplane multi and single-engine land, rotorcraft, and glider. The pilot reported 13,800 total hours of flight experience; of which, 400 of those hours were in the same make and model as the accident airplane. The five-seat helicopter was manufactured in 1973. It was powered by one Allison 250-C20B, 420 shaft-horsepower engine. The helicopter's most recent annual inspection was completed on March 3, 2012. At the time of inspection, the helicopter had accumulated 12,055 hours of service. The engine's most recent 100-hour inspection was completed at 11,928 hours. The 1453 recorded weather observation at Sarasota/Bradenton International Airport (SRQ), four miles east of the accident site, included wind calm, 10 miles visibility, few clouds at 4,000 feet, temperature 33 degrees C, dew point 20 degree C, and a barometric altimeter setting of 29.98 inches of mercury.
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.
Source: NTSB Aviation Accident Database
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