What happened
Following takeoff, as the crew retracted the flaps and landing gear, the low fuel pressure warning light for the #1 engine illuminated. At approximately 400 feet above ground level, a loud bang was heard, followed by an engine fire warning indication.
The flightcrew responded by shutting down the #1 engine and discharging both fire extinguishing bottles. To facilitate an emergency landing, the crew utilized the alternate system to extend the landing gear and performed a no-flap approach. During the landing, the crew applied the emergency brakes; however, they lost directional control, causing the aircraft to exit the side of the runway. The aircraft came to a stop with the fire extinguished. There were no injuries reported.
The investigation
An examination of the #1 engine area identified fire damage to the engine, nacelle, and wheelwell. Investigators discovered that a low fuel pressure warning switch snubber had failed. Evidence indicated that the snubber had been torsionally deformed during installation, which led to fatigue and eventual failure.
Gaps in the firewall allowed leaking fuel spray to enter the hot section of the engine, where it ignited. This ignition resulted in an explosion and subsequent fire. The fire propagation caused damage to the wires for the #1 standby hydraulic pump and resulted in a ruptured line in the #2 hydraulic system.