After maintenance on the engine fuel systems, like changing the Low Pressure fuel filter and pressure testing the fuel feed manifold, it is necessary to perform a high power ground run of the engines to ensure a good fuel flow rate is maintained.

After the test the engines are opened and inspected for fuel and oil leaks, as some oil filters will have been changed as well.

The engines are brought up to high power, about 3/4 throttle to an Engine Pressure Ratio (EPR) of 1.4 or so. The other engine will be set to around 1/4 throttle (1.2 EPR) to provide some balancing between sides.

The engines are tested one at a time as the aircraft's tyres and brakes are not able to hold back the power of both of these Rolls Royce Trent 89517 engines at once. They produce around 95,000 lbs (43,000kg) of thrust each at full power.

At around the one minute mark you can see the nose wheel tyres bending under stress due to imbalance of power from each engine.

I'm sorry that the sound cuts out but it was too loud for my camera's microphone.