Hi, i'm wondering if pilots still switch off HYD A or the HDMP for pushback with a tow bar and lockout pin installed for precaution?

The answer to this question is the answer to many questions in aviation, it depends. Specifically it depends on the operator's SOP, but the per the FCOM it only specifically mentions leaving the system A un-pressurized if the bypass pin is *not* installed. See FCOM vol 1, pdf pg 106 

 

Based on Boeing's procedures you can have either SYS A un-pressurized or have the pin in, but I'm sure there are airlines out there that call for SYS A to be off regardless of the pin as an added layer of safety or standardization.

Based on Boeing's procedures you can have either SYS A un-pressurized or have the pin in, but I'm sure there are airlines out there that call for SYS A to be off regardless of the pin as an added layer of safety or standardization.

 

 

Thats what i'm trying to find do companys inforce for SYSTEM HYD A to be unpressurized for pushback.

 

 

Thats what i'm trying to find do companys inforce for SYSTEM HYD A to be unpressurized for pushback.

 

I think Ryanair require the A pumps off for pushback. I'm sure there are some other operators that don't require it.

Thats what i'm trying to find do companys inforce for SYSTEM HYD A to be unpressurized for pushback.

 

Some do. I've been told SWA does.

 

As Steve mentioned, though, it's all company SOP. I, personally, leave it alone. It provides no added value, and is a potential missed item later on. Why bother, unless the bypass isn't working (which we don't really have to worry about in the sim)?

 

There's a bunch of stuff in aviation that companies do simply because "that's the way it's always been done." If you look farther back in history, I'm sure you'll find that aircraft didn't have bypass pins. Then again, if you look far enough back, we also had navigators and engineers. That doesn't mean that we still need them, or still need those procedures.

 

As another example, COA -> UAL used the ugly panel layout that emulated the old steam gauges for standardization across the 737 fleet (I think SWA did, too). Even after dropping the older 737s, they kept it. Once they realized "oh hey, it's 2010, I guess we can...you know...embrace uncluttered technology" that they updated the displays to use the newer style.

 

As Grace Hopper said:

"Humans are allergic to change. They love to say, 'We've always done it this way.' I try to fight that."

We push back with system A and B electric pumps on. Our normal procedure is to switch them on just prior to push back. However, if it's windy it's not uncommon to have one on earlier to keep the yoke from flopping about. The engine driven pumps are left on at all times unless an abnormal procedure calls from it to be turned off.

Thanks joe