What happened
On the morning of the accident, a Douglas DC-3C, registered as C-FBZN, departed from the La Grande-LG-4 airstrip in Quebec at 06:35. The aircraft, operated by Transfair, was performing a VFR charter flight to Lac Bienville to transport kerosene drums for a contractor. During the initial climb, after the landing gear had been retracted, the pilot began a left-hand turn at a low altitude.
During this maneuver, a critical mechanical failure occurred within the left engine. The crankshaft failed between the cylinder banks, which prevented power from being transmitted to the propeller. Although the rear portion of the engine continued to run and provided readings through the tachometer, the front section misfired because the pistons were no longer synchronized with the magnetos. This led to a rapid drop in RPM. As the propeller governor attempted to adjust blade pitch to compensate for the power loss, the resulting drag increased significantly. The crew was unable to feather the propeller in time to mitigate this drag.
In an effort to return to the airfield, the pilot continued the left turn. During this attempt to maintain altitude, the aircraft likely exceeded its critical angle of attack, leading to a stall and subsequent crash. There were 2 fatalities among the crew members.
Findings
Investigation into the accident revealed that while de-icing equipment was available at the airport, it was not utilized for the aircraft prior to departure. Instead, snow and ice were manually removed from the wings using a broom. Consequently, the Douglas DC-3C departed with residual ice accumulation on the wings. The combination of the engine's crankshaft failure and the aerodynamic complications caused by the unfeathered propeller led to the loss of control during the turn.