Accident Overview
On October 31, 2021, at approximately 1640 eastern daylight time, a Bell 47D1 helicopter (registration N132BR) sustained substantial damage during an accident in Zelienople, Pennsylvania. The pilot, who was the sole occupant, reported no injuries. The flight was conducted under Title 14 Code of Federal Regulations Part 91 as a solo instructional flight.
Flight History
According to the pilot, the helicopter had just completed an annual inspection at Zelienople Airport (PJC). The pilot met his flight instructor there to continue training for a rotorcraft-helicopter rating. After fueling with about 10 gallons, they departed for Butler Air Show Airport (3G9) in Butler, Pennsylvania. There, they landed, shut down the helicopter, and the instructor endorsed the pilot’s logbook for solo flight.
The pair returned to PJC, where the instructor disembarked while the engine continued running. The pilot then departed solo back to 3G9. Approximately 3 to 4 miles east of PJC, the engine sputtered, and both engine and main rotor rpms dropped. The pilot executed a 180° turn toward PJC; upon leveling, the rpms returned. He continued toward PJC for about 2 miles before total engine power loss occurred. The pilot entered autorotation, aiming for a flat open area, but lacked sufficient altitude and rotor rpm to reach it. He landed on sloped terrain, resulting in destruction of the main rotor blades and substantial damage to the landing gear and tailboom. The pilot stated there were no performance or handling issues before the power loss.
Pilot and Aircraft Information
The pilot reported 334 total flight hours, with 54 hours in helicopters and 14 hours in the accident make and model. The helicopter was manufactured in 1951 and powered by a Franklin 6U-335-A, 210-horsepower, carbureted engine. Its most recent annual inspection was completed on October 21, 2021, at 3,863.2 total aircraft hours.
Wreckage Examination
FAA aviation safety inspectors examined the helicopter. The 28-gallon fuel tank contained about 5 gallons of fuel. The accessory drive case at the bottom of the vertically mounted engine was found fractured. The tachometer generator, engine-driven oil pump, and one magneto had separated from the engine but remained attached by wires and hoses. Fractured pieces of the accessory case were sent to the NTSB Materials Laboratory for examination.
Analysis of the accessory case fragments indicated that the fracture surfaces were consistent with overstress fracture due to impact. The initial wreckage examination revealed no other mechanical anomalies. The helicopter’s subsequent owner blocked access to the wreckage, preventing further examination.
Weather Conditions
Weather reported in the area at the time of the accident showed atmospheric conditions conducive to serious carburetor icing at glide power.