A320 Brake

[Captain_BH]

Hi,

Why?
When you apply pedal brakes on A320 after ENG starts the pressure indicates Zero and not a positive value since brakes are being applied?

And What Does the pressure indicater indicates?

Thanks

[fantom]

Marhaba, ya Mahdi.

Are you rated? Have you FCOM?

[Captain_BH]

Marhabtain

I am not rated

I do have soft copies of FCOMS, But I couldnt find the answer there!

Could You help.!

[GearDoor]

Because the indicators show yellow/alternate braking pressure. After engine start, the brakes revert to the normal green system.

[Fargoo]

The triple pressure indicator has three dials on its front face. The top gage shows the system hydraulic pressure available (Yellow hydraulic system or accumulator) the bottom two gages show the hydraulic pressures:
- that go to the left MLG brakes

- that go to the right MLG brakes.


With Anti-skid turned on and park brake not set you'll be using normal braking hence no indication. Turn off the Anti-skid/NWS switch and you'll use altn braking and hence indication will show. Accumulator pressure is used for park brake so this is also indicated.

[Captain_BH]

Thanks
So the indicater indicates the yellow hyd pre. only then!
correct me if im wrong Please

Thanks again captain for your help!

[celtic mech]

Provided you are NOT using Alternate/Parking Brake, then the tripple indicator will not indicate anything. As a basic, in order to get Normal Braking you must meet the following conditions...Good Green Hydraulic Pressure, At least one channel of the BSCU Operative and the parking brake in the OFF position.

The minute the A-skid/NWS switch is placed in the OFF position, you are in effect switching off the BSCU...hence you are not meeting the requirements for Normal Braking. You are therefore in Alternate Braking and when you brake you will see movement of the Tripple Indicator pressure readings.

From the AMM...
The braking is normal:
-
when the Green high pressure is available,


-
when the A/SKID & NOSE WHEEL control switch is in the ON position,


-
and when the PARK BRK control switch is in the OFF position or the PARK BRK control is in the ON position and the parking brake pressure really applied is less than 35 bar (507 psi).