N272M
BELL 206
The helicopter had landed on an off-shore oil platform and was refueled. It then took off with one passenger. Shortly after lifting off, the pilot "heard a loud pop as the nose of the aircraft passed over the edge of the helideck. The noise was simultaneously accompanied by illumination of the engine out warning light and a needle split indication was observed on the engine and rotor tachometer gauge. As the aircraft yawed and lost climb performance, the pilot lowered the collective pitch full down and activated the floats. Upon landing on the water, the aircraft rolled left until inverted. The helicopter was later recovered and the engine disassembled and examined. The only anomaly noted was a loose Pc line, which would cause a loss of fuel flow and subsequent loss of engine power down to or below idle. It was determined that the torque required to realign the B-nut would be between hand-tight and 27 inch-pounds. The required torque is 80 to 120 inch-pounds. Torque values on the other air line fittings between the power turbine governor and the fuel control were found to range from 55 to 85 inch-pounds. A review of the engine maintenance records revealed that 36.7 hours prior to the accident, the turbine module was completely disassembled and overhauled. This would have required the removal and re-installation of the Pc line.
On November 1, 2009, approximately 1040 central standard time, a Bell 206L-1, N272M, registered to and operated by Rotorcraft Leasing Company LLC, was substantially damaged when it impacted water following a loss of engine power shortly after lifting off from an oil drilling platform. Visual meteorological conditions prevailed at the time of the accident. The non-scheduled domestic passenger flight was being conducted under the provisions of Title 14 Code of Federal Regulations (CFR) Part 135. The pilot was seriously injured and the passenger received minor injuries. The flight had just originated from platform High Island A442A, and was en route to platform High Island A515, both in the Gulf of Mexico. According to the company accident report, the helicopter had landed on the platform and was refueled. It then took off with one passenger. Shortly after lifting off, the pilot "heard a loud pop as the nose of the aircraft passed over the edge of the helideck. The noise was simultaneously accompanied by illumination of the engine out warning light and a needle split indication was observed on the engine and rotor tachometer gauge. As the aircraft yawed and lost climb performance, the pilot lowered the collective pitch full down and activated the floats. Upon landing on the water, the aircraft rolled left until inverted. The pilot and the only passenger exited the aircraft and inflated their life vests and crawled onto the belly of the aircraft and inflated the life rafts. The pilot and the passenger hung on to the side of one of the inflated life rafts until a nearby crew boat arrived and pulled them out of the water." The helicopter was later recovered and taken to the operator's base in Broussard, Louisiana, where, on November 19, 2009, the engine was disassembled and examined under the supervision of an FAA inspector. The only anomaly noted was a loose Pc line. According to Rolls Royce, a loose Pc line would cause a loss of fuel flow and subsequent loss of engine power down to or below idle. Using a picture taken during the on-site engine examination, the position of the B-nut on the fuel control when torque paint was last applied was approximated. Re-connecting the B-nut to the fuel control fitting, the torque required to realign the B-nut was between hand-tight and 27 inch-pounds. The required torque is 80 to 120 inch-pounds. Torque values on the other air line fittings between the power turbine governor and the fuel control were found to range from 55 to 85 inch-pounds. The turbine wheels and nozzles exhibited signs of corrosion from salt water immersion. The engine controls were intact with no apparent damage. A review of the engine maintenance records revealed that 36.7 hours prior to the accident, the turbine module had been completely disassembled and overhauled. This work would have required removal and re-installation of the Pc line.
A total loss of engine power due to maintenance personnel's failure to correctly torque the Pc line following removal and reinstallation of the turbine module.
Source: NTSB Aviation Accident Database
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