What happened
During the initial climb phase following takeoff, the number two engine of a Boeing 747 experienced a failure. The flight crew successfully executed the necessary shutdown procedures for the malfunctioning engine and declared an emergency to request a return to the departure airport. During the approach, the crew was forced to perform a go-around because air traffic control had instructed a different B-747 to hold at the runway threshold.
During the subsequent landing attempt, the first officer acted as the pilot flying. After the aircraft made a smooth touchdown and decelerated to approximately 80 knots, the captain assumed control of the aircraft. Shortly after this transition, the right main landing gear collapsed, causing the aircraft to slide along the runway until it reached a complete stop. There were 0 fatalities and 0 injuries reported in this incident.
Findings
Investigation into the engine failure revealed significant wear on the main fuel pump main drive shaft, which had worn down to the spline root. It was discovered that the grease applied to the main drive shaft output splines was not the specific type authorized by the required maintenance manuals. Furthermore, the magnetic seal compression O-ring was found to be hardened and displayed axial cracks on its inner diameter.
Regarding the landing gear failure, the right main landing gear assembly suffered a fracture of the trunnion bearing support fitting. This structural failure was attributed to fatigue cracking and stress corrosion cracking.