Accident Overview
On the morning of the accident, a Bell 206L-3 helicopter, registration C-GDTM, serial number 51366, operated by Héli Star Inc., departed La Tuque Airport, Quebec, at about 0750 eastern daylight time for Val-d'Or Airport, Quebec, where a 100-hour inspection was scheduled. The pilot, who owned the company and had approximately 5800 total flying hours including 780 on type, was alone on board. Weather conditions were favorable for visual flight rules.
Events Leading to Engine Failure
About 20 minutes after takeoff, at 2000 feet above sea level, the engine oil pressure gauge needle began to fluctuate within limits. Engine oil temperature was normal, no other anomalies were present, and the chip detector light was off. The pilot landed in a marsh as a precaution. After engine shutdown, an unusual amount of bluish smoke was observed from the exhaust. A quick inspection of the engine compartment revealed no oil leaks or damage.
The pilot contacted an aircraft maintenance engineer (AME) via satellite telephone. The AME recommended checking for oil leaks and verifying oil level, then performing an engine run-up. After the checks, the pilot started the engine; bluish smoke continued, but oil pressure stabilized at the lower gauge limit. Without further contacting the AME, the pilot concluded the gauge was defective and decided to move the helicopter to an adjacent road approximately one kilometer away.
Engine Failure and Hard Landing
While approaching the road at about 50 feet above ground, the oil pressure and torque indicators began fluctuating. An explosion occurred, and the engine stopped. The pilot performed an autorotation. During landing, the rear of the skids contacted the ground first, causing the nose to tip forward. The main rotor struck and severed the tail boom. The helicopter came to rest about 30 feet from the impact point. The pilot notified search and rescue via satellite telephone. The helicopter sustained heavy damage; the pilot was not injured.
Post-Accident Examination
Transportation Safety Board (TSB) engineering analysis determined that the area around bearings 6 and 7 had exceeded 900°C. At that temperature, oil dissipates rapidly via evaporation and burning. The oil did not return to the tank, leading to cavitation and pressure fluctuation. Oil temperature remained normal because the oil was not returning, which misled the pilot into believing the gauge was faulty. Bearing 8 had major damage from lack of lubrication, but none of the lines supplying bearings 6, 7, and 8 were obstructed. Due to severe thermal damage to bearings 6 and 7, the exact cause of their failure could not be determined metallurgically.
TSB Findings
The investigation identified that bearings 6 and 7 were destroyed for undetermined reasons, causing engine failure. Moving the helicopter when the engine was showing signs of malfunction contributed to the bearing failure. During the autorotation, the helicopter was not leveled, resulting in a hard landing. A risk finding noted that the flight manual's procedure for oil pressure fluctuation within limits with normal temperature could lead pilots to continue with a defective lubrication system.
Pilot and Aircraft Information
The pilot was certified and qualified in accordance with regulations. The helicopter was registered for commercial use with a valid airworthiness certificate. It was equipped with a Pointer Sentry ELT that activated on impact.