A320:hyd
 

Hello everyone,
Trying to come to grips with A320 hyd sys.:}
wonder why the B sys pump sw is guarded on the over head panel:confused:

can any one help? appriciate all inputs,thanks!:)

Because blue system hydraulics is automated to energise when configuration requires it.
The switch on the overhead panel is to allow for manual operation when aircraft is in a config that it wouldn't come on automatically (ie maintenance).

B sys
 

Blue has no backup like Y and G sys. Mistakenly selected off could cause some heartburn. So like most of the system's, if the switch is critical or ir-revokeable, put a guard on it that requires confirmation of the action.

Or as Sam tells me...it's a follow through from the A300's system.

The guarded pushbutton for blue pump on the overhead maintenance panel does not have an OFF function.
The button says blue pump ovrd, meaning that the button overrides the automatic function and as Fargoo pointed out, it can be used for maintenance purposes, for example.

Rubbish. It is on all the time. Read the books.

Sorry; should have added:
I believe it is guarded because there will be nothing to replace it if you (mistakenly) turn the elec pump off. If you turn Y or G Eng pump off, the PTU will provide.

would the rat get deployed if you switch off the Blue system pump?.
(I am refering to the switch on the Hyd panel and not the Blue Pump OVRD switch on the maint panel)

fantom, re-read the book Fargoo is right.
gearpins, No.

The electric pump starts automatically when one of the engines is started. It then operates continuously until the two engines are stopped.

Blue ELEC PUMP pb-switch
”AUTO” ( pb switch in )
● In flight:
- with the BLUE ELEC PUMP pushbutton at AUTO and AC power available, the electric pump operates.
● On Ground:
- the electrical pump is energized, provided one engine is running ,or
- the Blue Pump OVRD pb switch on the 50VU is pushed in.

”OFF”( pb switch out )
● OFF illuminates white
● the pump is de-energized
● deactivates the FAULT LT except at overheat-conditions.

still trying to figure out why blue pump sw is guarded and not the green or yellow?:bored:

As I see it, the pb is guarded as it would not be desirable in an ops normal situation to turn off the blue system pump for the reasons given by IFixPlanes. I am assuming to turn off the pump is NOT as irreversible action however, so whether or not you would need crew confirmation when operating the pb, as is required with any other guarded sw, is another question!

It's guarded because you don't want someone accidentally turning on the blue pump on the ground when someone is working on the aircraft.

As for my first reply being rubbish, I don't need to read the books as I work on them day in day out. I am correct :ugh:

Fargoo, relax. The o'head panel sw is an OFF sw, not an ON one. Nothing will happen if you poke it on the ground.
The maint sw is different; we are not talking about that, however.
You are confusing the switches, I fear.
Now let's all be friends.

Yep, I see I have gone off on a tangent.
What a plum :O
I was talking about the blue pump override sw, forgot about t'other one :ugh:

Now, 99% of posters here will not reply like that (me included).
I congratulate you. I mean it.

I feel a bit of a plonker to be honest but don't agree with going back and editing old posts to make myself look better.
Poor old Gearpins is probably totally confused now :O
Ta for your reply fantom :ok:

I believe that the guard was added by airbus after someone at the pointy end operated it by mistake.

By putting a guard over the switch it then has to be a 'positive' action required to operate the said switch. i.e. are you sure you really want to press this switch?

Sorry guys to add more confusion..
The overhead Blue override button (on the maintanance panel) is gaurded, ok I get this one and its function:
i.e. when you have to retract the flaps on stand and you will select the yellow and then the blue elec pump on by checking blue elec switch on auto pos on the hyd panel and blue override on the maintanaince panel)..
But the blue elec pump switch on the Hyd panel is not garded, the Rat yeas but that's a different story.
And its position in light off conf (normal pos) is auto with OFF in white light and Fault in Amber.
So in my opinion the 3 pump swithces on the hyd panel are all the same with a different switch on the maintanaice panel, garded but with a different function..
Correct?
Speevy

Sorry..
checked today on hyd panel, I was wrong: the blue elec pump it's garded...
Speevy

how about 330,340 etc? is it the same? can anyone through some light on it?

While I have no experience on the A320, I do know the reason some switches are guarded and some are not. Systems with guarded switches have no back up so it is protected to prevent inadvertent selection.