B737NG ELEC HYD PUMPS ON, ground crew
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Joined: Mar 2025
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From: USA
B737NG ELEC HYD PUMPS ON, ground crew
Hi. English is not my strong language.
i was reading the aircraft technical manual for the B737NG and reading hydraulics chapter.
Why must you make sure the ground crew are away from the nose wheel when turning on the electric hydraulic pumps?
before you turn on the pumps, does the nose wheel need a pin install?
i cant post urls.
i was reading the aircraft technical manual for the B737NG and reading hydraulics chapter.
Why must you make sure the ground crew are away from the nose wheel when turning on the electric hydraulic pumps?
before you turn on the pumps, does the nose wheel need a pin install?
i cant post urls.
Joined: Apr 2010
Posts: 1,320
Likes: 102
From: IRS NAV ONLY
If the nosewheel isn't completely centered, switching the system A hydraulic pumps will pressurise the NWS system, which will pretty quickly center the nosewheel. Now imagine what happens when a towbar is attached to it, and there are people around...
Hence if the towbar is attached or a towbarless tug is connected, the bypass pin should be installed before pressurising hydraulic system A.
Hence if the towbar is attached or a towbarless tug is connected, the bypass pin should be installed before pressurising hydraulic system A.
Joined: Oct 2013
Posts: 183
Likes: 3
From: McHales Island
Ryan,
Never ever, Ever, EVER apply hydraulic power WITHOUT clearance from the ground crew. The nose gear and tow bar are a good example as to applying hydraulics without clearance. Another example is with most hydraulically powered aircraft left on the ground for an extended period of time you may find ailerons, elevators and rudders etc out of their neutral position. As soon as you apply hydraulics they will move back to their neutral positions very quickly and if somebody has a hand, arm, leg, head etc in the wrong spot it could get (and has got) very messy.
Another trap is walking onto a dead aircraft and powering it up. If someone has shut the aircraft down previously and did not turn the hydraulic pumps off before shutdown and left the hydraulic switches in the ON position then as soon as electrics are applied on power up those pumps will be operating and things could/will move. Those swithch positions are the first things I look at when entering the flight deck, be the aircraft powered up or not. Hope this helps.
Rgds McHale.
Never ever, Ever, EVER apply hydraulic power WITHOUT clearance from the ground crew. The nose gear and tow bar are a good example as to applying hydraulics without clearance. Another example is with most hydraulically powered aircraft left on the ground for an extended period of time you may find ailerons, elevators and rudders etc out of their neutral position. As soon as you apply hydraulics they will move back to their neutral positions very quickly and if somebody has a hand, arm, leg, head etc in the wrong spot it could get (and has got) very messy.
Another trap is walking onto a dead aircraft and powering it up. If someone has shut the aircraft down previously and did not turn the hydraulic pumps off before shutdown and left the hydraulic switches in the ON position then as soon as electrics are applied on power up those pumps will be operating and things could/will move. Those swithch positions are the first things I look at when entering the flight deck, be the aircraft powered up or not. Hope this helps.
Rgds McHale.
Last edited by Capt Quentin McHale; 7th March 2025 at 00:32.
Joined: Apr 2013
Posts: 101
Likes: 122
From: UK
Absolutely agree with previous post.
There are a few things that one comes to see as 'big picture' items that can ruin your day. Hydraulic pumps on the ground are one. Another few are flaps, trim, pressurisation system. Before powering up, always make a point to check the hydraulic switches. Before departure, do the same with takeoff N1, flaps, trim, pressurisation panel. These are the things that can kill. Sure, there are many other things that can ruin your day but nothing so much as these items.
There are a few things that one comes to see as 'big picture' items that can ruin your day. Hydraulic pumps on the ground are one. Another few are flaps, trim, pressurisation system. Before powering up, always make a point to check the hydraulic switches. Before departure, do the same with takeoff N1, flaps, trim, pressurisation panel. These are the things that can kill. Sure, there are many other things that can ruin your day but nothing so much as these items.
