Quax .95
Looking at the pic of G-BOAB in the detuner brings me to the question how they performed the run-up. No brakes, just chocks?
What makes you think they would not have any brakes?? When performing any engine runs always set the brakes & chock the wheels.
Just think back to the A340 that was written off in France when the brakes were released & the aircraft jumped the chocks.
tristar 500