What happened
During a flight from Makovik to Rigolet, Labrador, the pilot of a Bell 206L Long Ranger experienced an engine chip light illumination approximately 12 minutes into the flight. The pilot performed a precautionary landing to inspect the chip detector, found a small amount of metal debris, and subsequently cleared the engine for departure.
Two minutes after the second takeoff, the aircraft was at an altitude of 1,0 and 000 feet when the engine suffered a total power loss following three loud bangs. The pilot initiated an autorotation and performed a forced landing on a coastal flat. During the touchdown, the front of the landing gear skids dug into the soft ground, causing the main rotor to strike and sever the tailboom. There were no injuries among the six occupants on board.
The investigation
The investigation focused on the mechanical failure of the Allison 250-C20R engine and the pilot's decision-making process. Investigators examined the engine at the accident site and later at a maintenance facility, where they discovered a mechanical lockup in the N1 shafting system. Laboratory analysis of the No. 1 bearing revealed that the component had failed due to wear on the separator and/or rollers, though the specific metallurgical cause could not be determined due to the extent of the damage.
Furthermore, the investigation looked into the maintenance procedures and training protocols. It was noted that the pilot had not been formally trained to assess engine airworthiness following a chip light, and the company's flight operations manual lacked specific guidance for such inspections. Additionally, the flight manual for this specific model suggested a less urgent response to chip lights than other models in the series.
Findings
- The engine stopped due to the failure of the No. 1 bearing caused by separator and/or roller wear.
- The pilot incorrectly determined the engine was airworthy and proceeded with the flight despite a recurring chip light.
- There was a lack of formal pilot training regarding the significance of recurring chip light indications and the necessity of performing a 30-minute ground run.
- The company flight operations manual provided no guidance for pilots on inspecting or assessing chip detectors.
Safety action
- The operator updated its ground training syllabus to include detailed instructions on checking chip detectors and amended its flight operations manual to provide pilot guidance.
- The manufacturer began revising the 206L flight manual to change the required response to chip light emergencies from "land as soon as practical" to "land as soon as possible."
- Transport Canada advised regional inspectors to audit training procedures and indicated that the Airworthiness Manual would be amended to ensure personnel are properly trained to assess aircraft airworthiness after performing chip detector checks.