767 Mel - C Isol Valve
 

Had the MEL for the C ISOL valve the other day, anyone know why the max alt of 27 000 applies??

From what I remember from my type couse the A.P.U. can be used to supply electric and air up to 27 000 ft but only electric from 27 000 ft. So if you have a problem that requires A.P.U. air above that altitude you can't have it. This is straight of the top of my head so don't take it as gosple!!!!!.
Rgds Dr I.

Center Hydraulic Pump cavitation
 

I can access our MEL on-line now. There is a note at the bottom of the MEL for this item that says:

"Note: Flight tests indicate that the center hydraulic pumps would start to cavitate at flight levels above 270."

So ftrplt is essentially correct in that apparently the APU loses enough pneumatic capability by FL270 that it is incapable of providing sufficient center hydraulic head pressure to keep the center pumps operating normally.

Isol MEL C?

I think she's a lovely girl. I wouldn't want to isolate myself from her in any event, unless that dreadful harpie, VIC B, was about to try to sing along with her....... :E

Oh sorry, this isn't about Spice Girls at all, is it? :O