Helmet fire, thats one of the better explanations and I'm still interested in a better explanation if possible. From the schematics I have, once emergency fuel is selected, the main metering valve is bypassed as you know and the emergency metering valve controls the fuel metering directly from the throttle. The reason I'm having trouble with it is that the main metering valve via the internal rock shaft with T1 and N1 controls the bleed normally. When emergency fuel is selected, the main metering valve no longer has an input into the bleed band, and the movement of the governor arm by beeping down has no effect what so ever on the FCU. By selecting emergency fuel, the N2 governor is removed from everything on the FCU because it inputs directly into the main metering valve, hence the question, why do we need to beep down after emergency fuel is selected? I'd be interested in anything you may have. This all stems from an Army Huey pilot asking me why we do it and I couldn't give him a definate answer.