A320 query

[A330AV8R]

Question FOR A320 Skippers !


You have engines running (Not on the Bay ) your Parking break is OFF however your standing still not taxing when you suddenly get a pressure increase on the 2 white indicators but nothing physically happenes to the aircraft .

I want to know what you do in both senarios

1 If you have your legs on the breaks

2 if you dont

thanks in advance :ok:

[A330AV8R]

and there is no loss of breaking mind you

[Dani]

What are white indicators? Do you mean the Brakes and Accu press indicator or something on the ECAM gear page?
In any case I would do a brake check, if brakes work normally (pedal press), if not, you still could think about the by-heart-item about Loss of Brakes.
I guess if the accu press indicators go up thats a sign that they were low before and if the parking brake indication goes up it's a sign that there is a problem in the parking brake, if noone touched the park brake handle.
Is this a quiz and you know the answer or is this a real question?

Dani

(I guess skippers and first officers are allowed to answer...)

[Idunno]

I think he's referring to the two white 'brake pressure' needles on the triple indicator.

The needles are (normally) only active when you apply the Parking Brake. Using the Brake Pedals gives no indication on the needles in (normal operation).

Normal braking is powered by the Green hydraulic system, and when you set the Park Brake a shuttle valve moves across to switch the power source to the Blue hydraulic system.
If the shuttle valve sticks then the transfer will not occur. A symptom of this is that you will see an indication on the pressure indicators when you actually shouldn't. This is why you look for a drop in the needles before taxi out after engine start (feet on brakes, park brake off).

Therefore, in your scenario, if you are using the Brake Pedals and see an indication on the triple indicator, then what appears to have happened is the shuttle valve has not transferred the source to the Green system - so you are braking on Blue.
You may have had a BSCU failure.
If it was anything else (Green hydraulic failure?) I'd expect ECAM warnings which you haven't mentioned.

If you are not moving or touching the pedals and the indictors suddenly show pressure then you would appear to have the brakes on in Blue. I've heard of an Airbus have this happen and they couldn't get the brakes to release. They were stuck at the hold for half an hour - caused major disruption.

In the first scenario, I'd go back for maintenance investigation, and I'd taxi slowly, being gentle on the brakes, and making sure we have at least got good Blue Hydraulics before going on stand. Get chocked ASAP.

In the second scenario I'd choose a tow-in.

Did I pass????

[FlightDetent]

QRH 5.02 (OPS DATA - hydraulic system architecture)

ALT/PARK brake : yellow system.

FCOM 1.32.30.p7

BRAKES and ACCU PRESS indicator:
ACCU PRESS: Indicates the pressure in the yellow brake accumulators.
BRAKES: Indicate the yellow pressure delivered to the left and right brakes,
as measured upsteream of the alternate servo valves.


FD.:=

[allthatglitters]

The blue Hydraulic system has nothing to do with the Braking System of any A320 Series I have worked on.

[what_goes_up]

Idunno
Guess you are A330 rated, right? It is the Blue System for the Park Break on the A330 and the yellow on the A320. (That is why you start Eng 2 first on A320 and Eng 1 first on A330).
Same same, but different, that is the hard bit on MFF, isn't it? :D

[FlightDetent]

Who cares. Problem lies with the alternate/parking brake kicking in. I like Idunno's reply. What say you?

FD.

[Idunno]

Ooops - spotted my deliberate mistake!:O Yes, I'm in 330 mode. RTFQ.
The answer is basically the same (thanks FlightDetent!) just the 'colour' of the hydraulic systems is different. It basically boils down to a problem with that park brake shuttle valve I think.