PDF of
full report available here (French).
Article at Flightglobal re findings include:
...power of the Rolls-Royce Trent 500 engines was increased to an engine pressure ratio of 1.25 - with the thrust levers corresponding to a position between maximum continuous thrust and maximum take-off thrust.
All four engines were operating. While the parking brake was on, registering 2,600psi, the inquiry says the applied thrust was around the limit of the parking-brake capacity.
At the time of the accident an Airbus employee was occupying the right-hand seat of the jet while an Abu Dhabi Aircraft Technologies technician was in the left-hand seat.
Flight-recorder data shows that, shortly after 16:02, the person in the left-hand seat warned that the aircraft was moving. The ground speed began gradually increasing to 4kt over the next few seconds and, after a second call that the aircraft was moving, the recorder registered pedal-braking and the deactivation of the parking brake.
Brakes on the A340-600 are linked to two hydraulic circuits: the 'green' normal circuit and the 'blue' alternate. The parking brake is on the blue circuit and only applies to the left- and right-hand main undercarriage bogies, not the centre bogie.
If the parking brake is released and the brake pedals applied, the 'green' circuit comes into play. The pedals act on all three main bogies.
Recorder data shows that 'green' circuit brake pressure on the A340 rapidly rose to 2,500psi while the 'blue' circuit pressure dropped.
About seven seconds after the first movement warning the nose-wheel was turned sharply right. Activating the nose-wheel steering inhibits braking on the central bogie, becoming completely ineffective past 20° of steering.
The aircraft swung 37° to the right but continued to accelerate, its speed increasing from 4kt to 31kt in seven seconds, before the aircraft struck the test-pen wall, demolishing its forward fuselage.