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HAWK21M
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Joined: Fri Jan 05, 2001 10:05 pm

B757 Fire Test Panel

Sun Jan 13, 2008 9:55 am

Its that same type of Question which AMMs can't answer & the ones that can are the Manufacturers or people that know about the development stages of the Aircraft type.

On the P8 panel of a B757,any version,not sure how its on the B767s.
The Fire test panel on P8 has a test button for "ENG" & "ENG/APU/CARGO"
Why is the ENG test button duplicated.Was there a reason for Boeing to do that.As both Tests test the ENG Fire/Overheat Elements.
Or was it to isolate a Fault.

Anyone.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tristarsteve
Posts: 3372
Joined: Tue Nov 22, 2005 11:04 pm

RE: B757 Fire Test Panel

Sun Jan 13, 2008 10:20 am

Quick answer without reading but
Eng APU Cargo tests the fire warning circuits.
ENG tests the overheat system for the internal cooling air. 4 thermocouples that measure that the internal cooling air is too hot. The effect to the flight crew is the same, they get a fire warning, but the warning comes from a totally different place, and the separate test switches help you to find which one it is..
 
Tristarsteve
Posts: 3372
Joined: Tue Nov 22, 2005 11:04 pm

RE: B757 Fire Test Panel

Sun Jan 13, 2008 2:53 pm

Another clue, when you do the fire tests select MSG page on the EICAS and watch the messages that come up while the test is in progress. You will see different messages on each test.
 
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HAWK21M
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Joined: Fri Jan 05, 2001 10:05 pm

RE: B757 Fire Test Panel

Mon Jan 14, 2008 6:50 am



Quoting TristarSteve (Reply 1):
ENG tests the overheat system for the internal cooling air.

Why was this not included in the common fire test or was it because the cooling air fire switches were added later?

Did something warrant a seperate switch?
Interesting.

regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
A/c train
Posts: 674
Joined: Sun Jun 10, 2001 7:57 am

RE: B757 Fire Test Panel

Sun Jan 20, 2008 3:38 pm

isnt the ENG/APU/CARGO test switch the AFOLTS system where as the ENG just does the Turbine OVHT detectors ? the turb detectors on the L/H side of the turbine case around 9 o clk ALF. The ENG switch is seperate in some way im sure but ive slept since working on 757's last.
 
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HAWK21M
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Joined: Fri Jan 05, 2001 10:05 pm

RE: B757 Fire Test Panel

Sun Jan 20, 2008 6:26 pm



Quoting A/c train (Reply 4):
isnt the ENG/APU/CARGO test switch the AFOLTS system where as the ENG just does the Turbine OVHT detectors

Why couldn't it be combined,or was it a later add on.
regds
MEL
I may not win often, but I damn well never lose!!! ;)
 
Tristarsteve
Posts: 3372
Joined: Tue Nov 22, 2005 11:04 pm

RE: B757 Fire Test Panel

Sun Jan 20, 2008 7:27 pm



Quoting HAWK21M (Reply 5):
Why couldn't it be combined,or was it a later add on.

Is it fitted to PW2000 engined aircraft?

I think that turbine overheat is a RR thing. They had a problem many years ago and have had it ever since.
Bit like the turbine overspeed system that is specail to RR.
 
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HAWK21M
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Joined: Fri Jan 05, 2001 10:05 pm

RE: B757 Fire Test Panel

Sun Jan 20, 2008 9:06 pm



Quoting TristarSteve (Reply 6):
Is it fitted to PW2000 engined aircraft

Not aware of P&W 2000 but its def on the RB211-535C & E4 versions.
regds
MEL
I may not win often, but I damn well never lose!!! ;)

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