B737 electric hydraulic pumps .....
08-19-2008 | 10:31 AM
#1
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B737 electric hydraulic pumps .....
-can someone clarify if the electric hydraulic pumps are turned on or off prior to engine start? Also does anyone have an actual checklist? (this question applies to the Next Generation series.)
Last edited by Brent H; 08-19-2008 at 10:49 AM.
08-19-2008 | 01:24 PM
#2
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From: Ca B737
It differs by airline. I've been out of the Boeing for a time but I believe we have all pumps on for start at Alaska. This is controversial to some because leaving the A pumps on pressurizes the nose wheel steering during push. Our ground crews must install a by-pass pin to open a by-pass valve so the NWS is not active during push.
You may like this site. http://www.b737.org.uk/ It is full of technical data/diagrams/tests for your reading pleasure.
You may like this site. http://www.b737.org.uk/ It is full of technical data/diagrams/tests for your reading pleasure.
08-19-2008 | 07:00 PM
#3
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From: 88B - Loud Pipes Save Lives
If I remember right the pumps on the 737NG aircraft are turned on at the gate before pushback and left on for the remainder of flight. I'm not aware of any reason to turn them off during engine start.
08-19-2008 | 07:06 PM
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From: F-4 Wild Weasel
It differs by airline. I've been out of the Boeing for a time but I believe we have all pumps on for start at Alaska. This is controversial to some because leaving the A pumps on pressurizes the nose wheel steering during push. Our ground crews must install a by-pass pin to open a by-pass valve so the NWS is not active during push.
You may like this site. The Boeing 737 Technical Site It is full of technical data/diagrams/tests for your reading pleasure.
You may like this site. The Boeing 737 Technical Site It is full of technical data/diagrams/tests for your reading pleasure.
Mike is right, A pumps pressurize NWS. We turn A (Engine Driven) off for push-back. But other airlines have they're own ops. Hope this helps
08-20-2008 | 12:31 PM
#5
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As long as the NWS lock-out pin is installed, we turn on both Elec pumps prior to push (good time to find if you have a system leak & it will bring up the LEDs if they are drooping). Eng pumps are never turned off (allowing for thermal expansion after shutdown).
08-21-2008 | 05:39 PM
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From: 88B - Loud Pipes Save Lives
I know in the 757/767 there is a procedure called Hard Starting which is used at hot and high altitude airports (Bogota comes to mind). In essence you turn off the Eng Driven pumps and Generators to allow the engines to spool up faster. Once you are stabilized at idle you turn them on.
08-27-2008 | 06:37 PM
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Errr...
SGRogue...the engine driven pumps are left ON all the time because that allows the hydraulic pump shutoff solenoid to remain de-energized, and thus doesn't burn out!
DAL4EVER...tell me, how does turning off the generator switches unload the engine during spool-up?
Cheers...E...
SGRogue...the engine driven pumps are left ON all the time because that allows the hydraulic pump shutoff solenoid to remain de-energized, and thus doesn't burn out!
DAL4EVER...tell me, how does turning off the generator switches unload the engine during spool-up?
Cheers...E...
09-01-2008 | 03:57 PM
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From: 88B - Loud Pipes Save Lives
Errr...
SGRogue...the engine driven pumps are left ON all the time because that allows the hydraulic pump shutoff solenoid to remain de-energized, and thus doesn't burn out!
DAL4EVER...tell me, how does turning off the generator switches unload the engine during spool-up?
Cheers...E...
SGRogue...the engine driven pumps are left ON all the time because that allows the hydraulic pump shutoff solenoid to remain de-energized, and thus doesn't burn out!
DAL4EVER...tell me, how does turning off the generator switches unload the engine during spool-up?
Cheers...E...
