Recent Airbus presentation on dual engine flame out shows the area above relight envelope as no relight attempt zone where you ensure EMER gen on and initial decsent etc. If engine could start anywhere then where was the need for the graph of relight envelope? Since the air density is low chances of relight are very low, you would not like to end up damaging the engine through repeated hot or hung starts.Latest manuals for CFM show 25000 ft where the envelope begins.
Last edited by vilas; 19th April 2013 at 02:42.