I remember back in '87 at Luton, an XP Parcels F27 was in the McAlpine hangar overnight on engine maintenance. Early morning came and it was rolled out for engine runs. GPU was plugged in and the number 1 engine fired up. The engineer powered it up but didn't realise the brakes were NOT on and the F27 duly jumped the chocks and engine number one tore into the GPU like a knife through butter....... Shame F27's aren't made by BOEING (Bits Of Engines In Neighbours Garden)
I'll get me coat....