APU Not Burning Fuel?

[RickButler 0]

Did a search but didn't come up with anything. Been running the 700 here a bunch, and it seems like the APU isn't burning any fuel. I did a 1 hour flight today, plus 20 minutes APU run time at the departure airport (left the APU on for the whole flight), and it didn't seem to burn any fuel, in fact the left tank had a hair more fuel than the right tank (which I believe is where the fuel burns from, if I remember correctly). I had 0 in the center tank, so it wasn't coming from there.Not a big deal, just wondering if anyone else is experiencing this, or am I losing my mind?Thanks!

[davierosoft 13]

Try to see from fuel load page on the fmc, it gives you an exact fuel value (1 lb, or 1kg precision) ten check if the fuel is burned.Try it with aircraft on ground, engines not running.Wit crossfeed closed fuel will be burned from left wing tank (if one pump running) or the center tank if left ctr tank pump is on (and fuel inside)

[RickButler 0]

Thanks Andrea, gonna try firing it up and leave the apu running for a while on the ground and see if it burns anything off the left wing tank. Will report back.

[RickButler 0]

So just did a half hour test, it burned 82 pounds in a half hour, so 164 pounds per hour on the ground in the 700. Seems low to me, but then I am used to the 800 which seemed to burn more. Does the 800 have a different APU? Were fuel flow rates tweaked with the SP1? Just curious.

[davierosoft 13]

Apu is the same for all NG models, it burns around 100Kg/hours, but depends on generator and bleed loads.If bleed is not used it will be much lower.I don't know about pmdg apu fuel rate and if its rate changes with loads, must try, but it is hard to see.

[RickButler 0]

Ah, okay makes sense then, I had it running with no load on it during that test. Thanks for the info!