During the landing rollout at East Midlands Airport, as the aircraft’s speed reduced through 60 kt, the co-pilot handed control to the commander who then made a brake pedal application to disengage the autobrake system. The aircraft shuddered and rolled slightly left-wing-low as the lower part of the left main landing gear (MLG) detached. The MLG inner cylinder had fractured through its chrome plated section, approximately 75 mm above the axle, allowing the left mainwheels and brakes to detach.
The cause of the fracture was stress corrosion cracking and fatigue propagation within the high strength steel substrate, leading to ductile overload failure. This was as a result of a small but significant area of localised heat damage to the chrome plating, leading to the exposure of the substrate to a corrosive environment. The exact source of the heat could not be determined.
Boeing 737-476(SF), EI-STD