What happened
During a visual flight rules cargo flight from Bronson Creek, British Columbia, to Wrangles, Alaska, a DC-4 experienced a series of critical failures. While climbing through 1,500 feet, the crew noticed a whining noise in their headsets, followed by erratic electrical instrument readings. Shortly after, the number 2 engine on the left wing began misfiring, and a fire warning light illuminated.
Although the crew attempted to execute the engine fire drill, the fire persisted. The captain visually confirmed that the left engine was on fire and subsequently observed that the number 2 engine had physically separated from the wing. As the aircraft lost altitude, the pilots applied maximum power to the remaining three engines and used full right-hand rudder and aileron deflection to combat severe yawing and rolling.
At approximately 50 feet above the ground, the aircraft struck a tree near the Iskut River and impacted the water. While the first officer and load master managed to swim to safety, the captain was lost in the river and is presumed to have drowned. The aircraft was destroyed in the accident.
The investigation
Investigators examined the recovered number 2 engine, propeller, and portions of the left wing. The examination of the engine and firewall revealed that an intense, localized fire had occurred between the firewall and the engine's accessory section. This fire caused the aluminum support channels to melt and fail, which led to the separation of the engine from the airframe.
The investigation also looked into the aircraft's maintenance and flight history. The 51-year-old aircraft had been maintained according to regulations, and the crew was fully qualified. However, the loss of the engine created a complex aerodynamic situation. The physical separation of the engine likely disrupted the control cables for the number 1 engine, further complicating flight control.
Findings
- An intense fire located behind the number 2 engine caused the engine to detach from the wing.
- The fire likely originated from a pressurized fuel or hydraulic line failure, though the specific ignition source could not be determined due to the extent of the fire damage.
- The physical separation of the engine caused the aircraft to become uncontrollable because the speed fell below the minimum control speed (VMCA) for that specific configuration.
- The loss of engine power, combined with the disruption of the number 1 engine's controls and significant changes in weight and balance, left the crew with no alternative but to force-land in the river.