A-320 accumulator low pressure and check

[Jimmy Hoffa Rocks]

In the cockpit preparation the older Airbus there used to be a brake accumulator pressure check where you release the parking brake and check for
a minimum of like 2000 psi. You need a minimum brake pressure from the accumulator.

In the FCOM it states the accumulator maintains the pressure for 12 hours.

The new aircraft the accumulator check is not done, why ? only checking the green accu pressure gauge. Yes there have been improvements in the alternate brake system.

In the new aircraft if you do a accumulator pressure check ( not in the FCOM, yes ) and the yellow accumulator low pressure ECAM comes on, on the second press,Airbus now does not have this check in the cockpit preparation, only you release the parking brake and check the pressure on the brake indicator.


Now you lose Green and Yellow you need 7 brake applications.
Personally, I want to know that I will have 7 brake applications if I need it. Right?

if you have a yellow low accumulator pressure warning and you call maintenance, they state this ( i think its in the maintenance control manual for engineers ? ), you need seven applications. If on the 6th application of the brakes with the parking brake off, the exam yellow accumulator low pressure comes on, then the airplane is a NO DISPATCH. Maintenance has this in their manual.

How do we know our accumulator pressure is enough ?

You press the brakes and you see how quickly the accumulator drops out of the green, How good are these accumulator gauges ?

Right, if you fly the older Airbus and the newer Airbus there is a difference in the cockpit preparation.

Interested in instructor input and from maintenance engineers.
Thanks for your input.

[vilas]

Previously Alternate brake was a Hydro Mechanical alternate brake system which was changed to electrical alternate brake system by MOI in 2007.This change provides Total segregation between normal and alternate circuit.
- System reliability improvement.
- Improvement of control braking sensitivity in alternate off mode
With the electrical alternate braking system, the alternate braking system is electrically controlled by the Alternate Braking Control Unit (ABCU) and fully monitored (any detected failure is signaled to the crew via ECAM warnings).
With this MOD the related procedures that were found unnecessary were changed accordingly.

[Superpilot]

I believe the new system also modulates brake pressure in case of loss of green thus capping both left & right to 1,000psi no matter how hard one pushes on the pedals. Can anyone confirm?

[WhyByFlier]

That's confirmed.

FCOM DSC 32-30-10

Depending on the brake pedals' demand, the ABCU controls the alternate brake selector and the alternate servovalves. Brake pressure and accumulator pressure are indicated on a triple indicator, located on the center instrument panel. To avoid wheel locking and limit the risk of tire burst, brake pressure is automatically limited to 1 000 PSI.

[MD83FO]

Is this a mandatory mod on all MSN's ?

[tubby linton]

Some of our fleet do not have it(UK operator).
I would suggest that the accumulator gauge has a small band on the scale and as long as the pressure was indicating within this range then you should get the stated amount of brake applications.

[MD83FO]

We're using ten year old A320s and the latest revision of the FCTM requires a brake transfer check for taxi, including slowing down to check efficiency.
Where in the books can i find weather the planes have the new BSCU standard.

[tubby linton]

Our Fcom have become electronic books and we have a single manual that covers all the aircraft. When there are differences the relevant chapter has a registration above it. In the old style Fcom there used to be a mod number at the bottom of the page and a decode table at the front of the fcom to tell you what the mod referred to. If you have the new standard there will be a decription of it in the fcom.
The new standard also allows nose wheel steering off the yellow hydraulics.

[Metro man]

Our EFBs allow a specific aircraft registration to be selected which brings up the relevant documents for that aircraft which is useful as we have a wide range of ages and specifications.

The pressure check as you start to taxi confirms that the transfer valve has shifted and braking pressure is being supplied by the GREEN HYD system. Whilst parked the pressure indicated is the YELLOW HYD system, on newer aircraft this is limited to 1000 psi. The accumulator pressure may bleed of over time but is soon recharged when the YELLOW electric pump operates, either manually selected or coming on automatically when the cargo compartment doors are opened.

[Superpilot]

or coming on automatically when the cargo compartment doors are opened.

Aaah, so that's why we don't need to do it all the time. It's because the loadies inadvertently end up doing it for us before we arrive at the aircraft... Thanks

[FLEXPWR]

On the overhead CB panel, check the braking system: if ABCU is listed, then the new electrical alternate braking system is fitted.

[Citation2]

Does that mean that in case of G+Y Hyd failure , the maximum braking of 1000 psi will be monitored by the ABCU?