Engine Failure and Emergency Declaration
Shortly after takeoff, the No. 2 engine failed, and the flight crew accomplished shutdown procedures for that engine. An emergency was declared, and the crew requested to return to the departure airport.
Go-Around and Landing
On approach, an engine-out go-around was required because air traffic control had instructed the flight crew of a Boeing 747 to "position and hold" on the end of the runway. The first officer was the pilot flying. The subsequent touchdown was uneventful. As the airplane slowed to about 80 knots, the captain took control of the airplane. Shortly thereafter, the right main landing gear collapsed, and the airplane slid to a stop on the runway.
Examination of the No. 2 Engine
Examination of the No. 2 engine revealed that 80 percent of the main fuel pump main drive shaft was worn to the spline root. The grease used to lubricate the main drive shaft output splines was not the authorized grease specified per overhaul manual 73-11-1 or MIL-G-81322. Additionally, the magnetic seal compression O-ring, which rides on the drive gear journal outer diameter, was hardened and exhibited inner diameter axial cracks. The component manufacturer indicated that the failure of the magnetic seal was the first such reported incident in 30 years. The manufacturer agreed to review operational data from airlines to reevaluate the mean time between overhaul intervals for the seal and to recommend an inspection interval as necessary.
Examination of the Right Main Landing Gear
Examination of the right main landing gear revealed a fracture failure of the trunnion bearing support fitting, caused by fatigue cracking and stress corrosion cracking.