B 777 FWD Cargo A/C
 

Good evening, I have a question: if set out of the OFF position and not in AUTO, does the B 777-200 FWD Cargo A/C affect fuel consumption?
I could not find any answer on my manuals!
Thank you!

I believe it's true for all passenger-outfitted 777s... there is no switch for heat/cooling in the forward cargo compartment. As far as the rest of the belly, there are switches, but switch position will not affect fuel consumption at all.

Erm... yes it will? Aft and bulk cargo heat use bleed air directly, any increase in bleed usage will increase fuel consumption, no?

And as for the forward cargo A/C selector - its a temperature zone like any other in the cabin, but switching it off will close the FWD Cargo A/C SOV and thus reduce pack load which in turn should reduce fuel consumption somewhat. Whether its significant or not is a different question of course...

Are you sure stbyrud.

The forward cargo compartment heating system uses vent air from the forward equipment cooling system. There is no control switch unless you put it in override mode.

Its not fitted on every 777, its an option on the passenger 777 range. You are correct, normally its only heated with exhaust air from the electronics (737 style), if installed the FWD CARGO A/C temperature selector (which can also shut off the entire system) is above the normal air conditioning panel (next to the humidifier switch - not that anybody bought that option).

From the good book of my company's implementation of FWD Cargo Air Conditioning:

"When the FWD CARGO A/C selector is in AUTO, the forward cargo heating
system is shut off and a target temperature is displayed on the AIR synoptic.

Automatic ventilation ensures that smoke and objectionable odors do not enter the flight deck or passenger cabin.

If the selector setting is not available because of system failure, the packs maintain the last temperature set by the FWD CARGO A/C selector."