Originally Posted by
Rostermouse
No, it is as The Banjo says. It is to improve stall/surge margins on the engine on the failed pack side, because (in simple terms) with less air being extracted from the compressor and a worn engine there is an increased likelihood of stall/surge during descent (higher adverse pressure gradient across the HP comp). One EU airline had 3 within a couple of years. Compare with the procedure for engine stall which for the EAI ON to improve margins - same principle, just preventative.
Rostermouse, thanks again for the clarification. Much appreciated
