On 30 August 2010 at approximately 2330 Pacific Daylight Time, a Boeing 747-438 aircraft, registered VH-OJP, departed San Francisco International Airport on a scheduled passenger service to Sydney, Australia. As the aircraft passed through 25,000 ft, the aircraft's number 4 engine sustained an internal mechanical failure, resulting in the energetic release of debris and puncturing of the engine casing and nacelle. The engine was shut down and the flight crew returned the aircraft to San Francisco, where it landed without further incident.
The number 4 engine had ruptured through the left and right sides of the turbine case and fairings, resulting in a large perforation in the right side of the engine nacelle and several smaller punctures through the left side.
Debris ejected through the hole in the right side of the engine had impacted the underside of the wing, producing superficial nicks and scratches to the wing skin. There was a puncture through the composite, leading-edge, variable-camber flaps and the associated torque tube was slightly bent.
There was no airframe damage inboard of the number 4 engine.
Read the preliminary report: Uncontained engine failure and air turn-back, near San Francisco Airport, United States, on 30 August 2010