Propair Flight 420Thursday June 18, 1998
Flight 420 took off from Montreal's Dorval Airport on a flight to Peterborough About 12 minutes after take off, at an altitude of 12,500 feet, the crew advised ATC that they had a hydraulic problem and requested clearance to return to Dorval. The crew then advised ATC that the left engine had been shut down because it was on fire. The crew decided to proceed to Mirabel International Airport. Then crew then advised ATC that the engine fire was out. On final for Runway 24, the crew advised ATC that the left engine was again on fire. The landing gear was extended on short final, and when the aircraft was over the runway, the left wing broke upwards. The fuselage inverted, struck the runway and slid 2,500 feet and came to rest on the left side of the runway. PC: The crew did not realize that the pull to the left and the extended take-off run were due to the left brakes' dragging, which led to overheating of the brake components. The dragging caused overheating and leakage, probably at one of the piston seals that retain the brake hydraulic fluid. When hydraulic fluid leaked onto the hot brake components, the fluid caught fire and initiated an intense fire in the left nacelle, leading to failure of the main hydraulic system. When the L WING OVHT light went out, the overheating problem appeared corrected; however, the fire continued to burn. The crew never realized that all of the problems were associated with a fire in the wheel well, and they did not realize how serious the situation was. The left wing was weakened by the wing/engine fire and failed, rendering the aircraft uncontrollable.