gloom wrote:The only question remaining is the zoning (I've seen a couple of birds with different temps in front, middle and back zone of the plane), but that's easy trick to do either by multiplying mixers, or adjusting on manifolds, so I can answer myself that
As you say this is a trim air function. Control wise it varies a bit. On the 330 overhead panel we have a knob for the cockpit temp and a knob for the cabin temp. The cabin crew can then set individual zones within +/- 2 degrees from what we've set in the cockpit by using the panel by the L1 door. The 350 also has an additional "Purser Select" setting on the cabin temp knob, allowing the cabin crew to adjust the cabin temp independently.
I have another question(sorry for deviating from the topic)
1) How we turned off the APU? I mean the correct sequence.
2) How the APU is fed with fuel and is there a dedicated pump? How the fuel is supplied to the APU for starting it. I have turned on the APU with out turning on any fuel pumps.
On the Airbus there's an APU master pushbutton and a start pushbutton. Press the master pb and then the start one.
On the 330 it is rather complex due to the trim tank. There is a standpipe from the wing tanks to the APU and trim tank. The APU is fed from the trim tank if there is fuel in it by using the aft APU fuel pump, and from the wing tanks otherwise using the forward APU fuel pump. If the standpipe should be empty for some reason (well, not so much empty filled with air) you can't start the APU as the fuel won't be sucked up. There are separate aft and forward transfer tanks for CG trimming with the trim tank.
On the 350 it is way simpler. There's no trim tank so it's just a pump and a standpipe.