Engine operation without cowlings
The gas turbine engine will happily run with no cowlings fitted. Regular occurrence when ground running for leaks etc. However there is no fire protection in this config as the cowlings form part of the air tight cavity for the retardant to be ejected around the engine. Both left and right cowls were not fully latched (for whatever reason) and when the right hand cowl came off it punctured something, possibly a fluid pipe on the side of the engine this resulted in that fire.Its possible the fire warning system was not triggered because, again the cowlings play a major role in ensuring the fire wires around the engine quickly pick up any abnormal sudden temperature rise