B777 APU to pressurize in flight ?
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B777 APU to pressurize in flight ?
Just doing a little thinking , hypothetically
OK so we are in the cruise ( FL 330)over high terrain ( say 15000 ft)
We get EICAS , BLEED OFF ENG L. OK .
Shortly afterwards we loose The Right Engine.
OK I know we have a drift down to consider and off course will have a depressirisation strategy to follow ( while the cabin slowly depressurises). Proceduraly OK.
But what about starting the APU ( once we have done the important stuff of course) and using it to pressurise the Cabin.
Assuming we are at a weight where we can maintain say FL210 ENG OUT.
I see the MEL is the only source of guidance ( Turn Off ENG Bleed Switches , PUT on APU bLEED Switch , Turn off wing Anti Ice, See you are FL220 or lower etc etc)
However are we really going to be doing this ( consulting the MEL at this time) ?
Is there any other reference apart from the MEL or systems knowledge that will lead us to pressurising the cabin this way ?
My present company is draconian to anyone who thinks outside the box , following a procedure withiut guidance from a Checklist etc.
Just curious chaps , and ladies , your views ?
OK so we are in the cruise ( FL 330)over high terrain ( say 15000 ft)
We get EICAS , BLEED OFF ENG L. OK .
Shortly afterwards we loose The Right Engine.
OK I know we have a drift down to consider and off course will have a depressirisation strategy to follow ( while the cabin slowly depressurises). Proceduraly OK.
But what about starting the APU ( once we have done the important stuff of course) and using it to pressurise the Cabin.
Assuming we are at a weight where we can maintain say FL210 ENG OUT.
I see the MEL is the only source of guidance ( Turn Off ENG Bleed Switches , PUT on APU bLEED Switch , Turn off wing Anti Ice, See you are FL220 or lower etc etc)
However are we really going to be doing this ( consulting the MEL at this time) ?
Is there any other reference apart from the MEL or systems knowledge that will lead us to pressurising the cabin this way ?
My present company is draconian to anyone who thinks outside the box , following a procedure withiut guidance from a Checklist etc.
Just curious chaps , and ladies , your views ?
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Thats been a standard sim upgrade loft scenario in EK for years. You pretty much knew what was coming when you saw the high MSA routing and the MEL.
Its not a rapid loss of cabin pressure when you lose the opposite engine so if you do the memory items then nip down to say, 20,000' while starting the APU you can even avoid the CABIN ALT EICAS.
There is a section in the checklist preamble and probably your FOM with gives you the flexibility to be creative when checklists do not cover a particular situation.
It should be briefed for prior to departure though.
Just noticed your location - not EK are you?
Its not a rapid loss of cabin pressure when you lose the opposite engine so if you do the memory items then nip down to say, 20,000' while starting the APU you can even avoid the CABIN ALT EICAS.
There is a section in the checklist preamble and probably your FOM with gives you the flexibility to be creative when checklists do not cover a particular situation.
It should be briefed for prior to departure though.
Just noticed your location - not EK are you?
Last edited by NO LAND 3; 1st Nov 2009 at 12:30.
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I know its an old loft scenario. However if you despatch under the MEL with the Bleed off fault , then you are directed in the MEL with what to do in the event of the scenario described. However , if it just happens in flight the way I described. You have to configure the bleeds from memory to get the APU to provide the packs ( Not rocket science , but stepping outside the box) . EK, EY ,QR , who cares where I am from its all the same sandbox 
and it sucks.
and it sucks.
Depends which engine you've lost , if its number 2 you could only use no 1 OR APU for packs . Anyway whats the worry , one pack is MEL 'able with altitude restriction so wouldnt really improve things ? (if you can get it to start at altitude !)
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I think I see your point which is how come in the Boeing such a hypocritical system has evolved. On the one hand we have a super smart electronic checklist integrated with the aircraft systems which we are trained to strictly follow. And yet this holy grail of a philosophy gets casually chucked out the window when the aircraft is dispatched under an MEL.
Furthermore, the associated MEL procedures are often poorly written, ambiguous and complex.
Is that the point you were making?
I do concur Sir!
Furthermore, the associated MEL procedures are often poorly written, ambiguous and complex.
Is that the point you were making?
I do concur Sir!
