A320 Brakes check

[Speedwinner]

Hello folks !

Had a recent discussion. The captain came from the 737. He said that when he releases the parking brake after engine start he always presses the brakes before releasing the parking brake handle. Means he holds the brakes then released the parking brake. So he said that this was the official brake check according to Airbus. I was thinking before brake release the yellow system has full authority over the brakes and after releasing the brakes and pressing it again the change between the systems yellow And green is done . Can somebody help me on that?

[Airenn]

according to the FCTM , brake check is done after the park brake is released and the a/c starts to move.

you are correct

[framisalvador]

Hi there gentlemen, this is all I found... make your choice :8

FCTM NO-040 taxi

When cleared to taxi, the PF should set the Parking Brake to "OFF". When the aircraft starts to move, the PF should check the efficiency of the normal braking system by gently pressing the brake pedals.

AFM Normal procedures

 When starting to taxi or after any BSCU reset on ground:
As soon as the aircraft starts to move, check the efficiency of the braking system by pressing brake pedals.

A320 Family Instructor Support

Before taxiing, the brakes must be checked; this check consists in verifying that the Normal braking has actually taken over when parking brake is off, and thus that both BRAKE yellow pressure indications remain at 0 when pedals are pressed. The most comfortable way to carry out this check is:
- while parking brake is ON, press pedals down and
- release the parking brake and check that both BRAKE yellow pressure indicate 0.
Another method consists in releasing the parking brake, in order to set the aircraft moving; then the pilot presses the pedals smoothly. He checks:
- the aircraft decelerates gently,
- the Yellow brake pressure indicates 0 on both gages of the indicator.
Be aware of Passenger comfort.

Safe flights!!

[Umidori]

Never seen the instructor support.

For brake check, I simply think following FCOM is correct and accurate cause it's SOP...mmm.

So parking brakes released, the aircraft starts to move, then brake check.

[vilas]

Instructor support is an ancient document. FCOM is the correct way to do the check.

[framisalvador]

Sounds good to me Umidori, it's exactly how I do it, and I agree FCOM is quite clear about it.
I was just lying out all the info I could find about it to be able to understand why someone would do it differently...
On the other hand, first page of the instructor support states that obviously FCOM rules over in case of any difference between the two documents...

[FlightDetent]

FCOM PRO-NOR-SOP-10 "A" Taxi (relevant DUs only).

http://i67.tinypic.com/2vrtks6.png

This is the FCTM wording, extended version applicable for the older aircraft:
When cleared to taxi, the PF should set the Parking Brake to "OFF". When the aircraft starts to move, the PF should check the efficiency of the normal braking system by gently pressing the brake pedals, to ensure that the aircraft slows down. The PM should also check the triple brake indicator to ensure that brake pressure drops to zero. This indicates a successful changeover to the normal braking system (green pressure has taken over yellow pressure). Although green hydraulic power supplies the braking system, each time pedals are quickly pressed, a brief brake pressure indication may appear on the BRAKE PRESS indicator. No maintenance action is required if the pressure peak is less than 2 000 PSI. If a “spongy” pedal is felt during taxi, this indicates a degraded performance of the alternate braking system. Spongy pedals can change the feeling of braking.

[ahramin]

In older braking systems and on smaller airplanes the brakes have to be applied and then the parking brake set to trap the applied pressure. In order to release the parking brake many of these systems also need the brakes applied in order to release the parking brake.

I've noticed a tendency for many pilots to apply pedals before applying or releasing the parking brake on Airbii aircraft, either because they don't understand their brake system or because they just aren't thinking about what they are doing.

[Rick777]

The OP mentions 737 first and then asks about 320. Two very different planes with very different brake systems. As mentioned above 737 brakes are set by pressing pedals and applying parking brake which locks the pedals down. 320 parking brake is a switch and uses a different hydraulic system than normal brakes.

[FlightDetent]

I do set the electrical-switch parking brake on before releasing the pedals.

It never occured to me that this was a bad habit carried over from my 1237 worth of 737 hours, which as a F/O I did not taxy. All these years I fooled myself into believing it was the way to assure the aircraft is stationary. :(

[oicur12.again]

On the subject of brakes, i am interested to know what other airlines do wrt to releasing the park brake at the gate.

SOP at my new employer is to release the brakes after shut down every time regardless of temp yet FCOM states the parking brake should he released if one temp is above 300.

Previous carriers have left the brakes on as per FCOM.

[vilas]

Although FCOM cautions about 300C, releasing brakes after chocks ON helps cool them faster. So as required is OK.

[Check Airman]

FCOM states the parking brake should he released if one temp is above 300

What does it say to do if the temps are below 300?

[Amadis of Gaul]

What does it say to do if the temps are below 300?

Get mad at yourself for not getting on the brakes like you mean it.

[A320ECAM]

Just remember guys, the simple answer is always the best answer.

After push and start:
- ensure the ground crew have vacated your area,
- request taxi clearance,
- release parking brake,
- set just enough thrust to get the bird moving,
- idle thrust again (no point braking when you're applying thrust)
- press on both brake pedals

Is the braking pressure well distributed?
Do the brakes feel sluggish?
Does the bird pull to one side (i.e. brake failure)?

That's all you need to really know - are your brakes working? No point doing an entire flight, land at your destination at 134kts and realise your brakes have failed!!

[oicur12.again]

"What does it say to do if the temps are below 300?"

Depends, my present airlines 320 says "as required", a previous airlines says "brakes on".

"releasing brakes after chocks ON helps cool them faster"

True but I am not sure faster cooling is the aim. Even cooling is more important for brake life and is achieved with the park brake on.

I cant find a reference for this other some guidance from an airline several jobs ago.

[oicur12.again]

Interesting follow up.

I was asking our handling engineer (opposition larger airline A320 operator)on a recent turnaround and he mentioned that he thought it was odd that our airline always releases the park brake where his airline only does for hot brakes.

His opinion was even cooling was more important than rapid cooling.

[goeasy]

I have also had engineers say that 330 brakes cool faster with park brake on... (on an aircraft without fans).

[Escape Path]

Our FCOM says don't set parking brake with brake temp above 500 (not 300), unless operationally necessary. It also says setting park brake off increases cooling performance. We always set brakes off after ground confirms chocks in place. I fail to see the reason why leaving the brakes set would make the brakes cool more evenly as the brakes would be in contact with the disc creating a "hotspot", no?

By the way, we have as SOP to check the brakes after the aircraft starts moving, by FCOM and FCTM

[vilas]

goeasy
Why go by hearsay when the FCOM says the following:
"Releasing the parking brake prevents the critical structures from being exposed to high temperature levels for an extended time. However, if operational conditions dictate (e.g. slippery tarmac), the parking brake may remain applied."
Ask the engineer to show the reference.

[oicur12.again]

"Releasing the parking brake prevents the critical structures from being exposed to high temperature levels"

True, however this line applies when "one brake temp is above 300".

[vilas]

This discussion is waste of time because it is based on a hearsay which could very well be erroneous.