What happened
In the early morning hours, a Cessna 421C, registration C-GVPB, departed Charlevoix Airport, Quebec, on a VFR charter flight bound for Trois-Rivières. The aircraft was operated by les Ailes de عدم Charlevoix inc. and carried one pilot and five passengers.
Shortly after departing runway 15, onlookers observed greyish smoke trailing from the left engine. The aircraft began a steep left turn and entered a descent. The flight path became uncontrolled as the aircraft yawed and rolled, eventually crashing approximately 1.14 nautical miles southeast of the runway end. The impact and a subsequent post-crash fire destroyed the aircraft, and all 6 occupants were killed instantly.
The investigation
Investigators examined the wreckage and the two Teledyne Continental GTSIO-520-L engines. Metallurgical analysis of the exhaust stacks revealed that the left engine was significantly colder than the right, indicating it was not operating normally prior to the crash. While the engine teardown showed no internal mechanical failures that would prevent power production, evidence suggested the left propeller was feathered at the time of impact.
Analysis of the supercharging system indicated that the left supercharger was not functioning. The investigation also looked into the aircraft's flight instruments and the emergency locator transmitter, though the latter failed to signal due to damage sustained during the impact.
Findings
- The left engine propeller was in a feathered position at the moment of impact.
- The left engine supercharger was inactive during the final moments of flight.
- A rupture in one of the oil lines within the supercharging system likely led to a loss of oil pressure in the left engine.
- The appearance of greyish smoke was consistent with oil from a major leak spraying onto the exhaust stacks.
- The sudden difference in thrust between the two engines caused a significant yaw, initiating the left turn.
- The pilot failed to maintain the aircraft's minimum control speed (VMC), leading to a loss of control.