View Full Version : 767 Equipment Cooling Question

20th Oct 2015, 23:01

I'm doing some initial self study for an upcoming 767 course, and have a quick question about the Equipment Cooling system.

Where is the inboard supply valve located and what is the source for its air supply? The schematics seem to indicate that it's located somewhere in the forward cargo compartment (fwd belly/lower lobe).

So the supply for the forward equipment cooling is: 1) cabin discharge air that is vented into the forward cargo compartment and maintained at 7 degress by the ECS and 2) supplemented by the air that is recirculated through the equipment cooling system after passing through the skin heat exchanger (in flight or on ground with OAT < 7 degrees).

Sorry for the simple question, I just wasn't successful in researching this on my own.

21st Oct 2015, 03:01
Do you have access to the Boeing Maintenance Manual and Wiring Schematics? (21-58-00 & 21-58-06 Schem 2 respectively)

"The inboard supply valve is installed behind the forward cargo compartment left sidewall, approximately 13 feet (4 meters) aft of forward endwall."

Some diagrams show it about 7 or 8 panels from the front of the cargo. Note that there are variations. e.g. Some wiring schematics show it at STA 470 WL 187 LBL 75 on later model -300's and at STA 515 WL 187 LBL 75 on earlier model -300's. Please refer to your own manuals for applicable locations.

Being in the sidewall, the air supply is cooled by contact with the (probably uninsulated) skin.


(EDIT) some pictures show the valve just forward of the forward cargo door ball mat area just below ceiling height (the inlet for the valve is aft of this, one panel behind, just on the forward edge of the ball mat)

21st Oct 2015, 04:30
Thanks for the reply, I am just going off the Boeing FCOM for flight crew, I don't have access to the maintenance manuals. I appreciate the information. I have read from other sources that the inboard supply valve closes in flight as well, but the FCOM doesn't seem to state that explicitly (unless I missed it).

21st Oct 2015, 05:58
Yes, on the 767-300, the inboard supply valve is normally closed in flight and the system goes into a closed loop primarily using the skin heat exchangers for cooling.

On the 767-200, my books say that the inboard supply valve can open in flight if the aircraft skin temperature is more than 7degC.

21st Oct 2015, 18:58
Thanks, that is useful to know as we fly both the -200 and -300.