(auto) brakes B767

[blue belly]

I am new on the B767- Can somebody tell me what other airlines do re Autobrake on B767- it seems to give quite hot brakes (up to 4) using settings 1-2 land wt 125t. When do other airlines call for brake cooling? Is it desirable to use manual brakes instead? would appreciate an information exchange...thks

[HPSOV]

In my company it is policy to use autobrakes, and I'd be surprised if this wasn't the case elsewhere.
Using manual braking will make no difference to the temperature of the brakes, its just the dissipation of energy.
If you look in your performance manual there will be a brake cooling schedule, this states when brake cooling is required.

[BOING]

Some 767s have carbon brakes some have steel brakes. Operating technique is different. As a compromise my outfit says, if conditions permit, autobrake level 2 is considered best. Which type of brake do you have? As a rough rule it would seem that using as little brake as possible with the steel brakes (runway permitting) is best. Even, dare I suggest it, manual braking after plenty of reverser. With the carbon brakes it is, strange as it may seem, the number of applications not really the amount of braking that causes problems. Therefore, I am told that one long fairly heavy brake application is best with carbon brakes. I am told the carbon brakes do not mind the heat so much and even work better when they are warm.

I mention the carbon brakes because on our fleet only the newer aircraft with carbon brakes have the temperature readout you mention so I am guessing this may apply to your aircraft.

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[AIRLIFT]

On our 757 we have some with carbon and one with steal. Our SOP recommends level 2 as well, for a couple of resons. The carbon breaks will last longer and as somone said they work better when they reach a certain temperature. The steal ones are a diffent thing, temperature does seem to rise more with a higher setting. Level one sould be a better choice providing the runway lengh is no factor.

[blue belly]

our planes have the carbon brakes, but I find it strange that the brakes get up to 3-4 on the temp reading after a landing-this seems high to me, but possibly it is quite normal..... cooling equipment is required by some airlines when the brakes get to 4 I believe....can someone help here

[QAVION]

"our planes have the carbon brakes, but I find it strange that the brakes get up to 3-4 on the temp reading after a landing-this seems high to me,"

Seems a little high to me, too. Is the whole fleet doing this... or are you flying the same aircraft every day? Are particular brakes reaching this level.. or are all brakes going this high?

Talk to your engineers. Make sure you have the right model A/B / Antiskid computers fitted...and they are at the correct mod status.

Rgds.
Q.

[BOING]

Remember the autobrakes are looking for a rate of deceleration. This deceleration is achieved by a combination of three different components. Drag due to flaps and spoilers, reverse thrust and wheelbrakes.

Here are two scenarios. Same aeroplane and conditions using two different techniques.

In the first case we set autobrakes one (low level of deceleration). On touchdown the spoilers deploy and by magic we go straight into a high level of reverse thrust. THE RATE OF DECELERATION MAY BE HIGH ENOUGH SO THAT THE WHEELBRAKES ARE NOT REQUIRED TO PROVIDE THE SELECTED DECELERATION. The brakes will hardly be applied. At about 80 knots you will come out of reverse, the aircraft will sense deceleration has stopped and now the brakes will automatically apply until the aircraft stops. The brakes will hardly be warm.

Scenario two. You select a high autobrake setting, 3+. On touchdown the spoilers deploy as before but now you are late selecting reverse or you use very little reverse. IN ORDER TO PROVIDE THE SELECTED RATE OF DECELERATION THE AUTOBRAKES WILL IMMEDIATELY APPLY TO A HIGH LEVEL. The brakes do most of the work and absorb most of the landing energy. They will be very warm.

The point is that autobrakes are only part of the stopping equation. Proper reverser use is equally important. I notice a strong tendency on the line for pilots to use too little reverse too late. This is argued to be better for the passengers as they are not frightened by the noise and forces. So the brakes get very hot.

With carbon brakes you do not want them to cycle on and off frequently during the landing run as this increases wear. With a low autobrake setting this may happen. Therefore, with carbon brakes you select a setting which puts the brakes on and tries to keep them on without cycling. This is why level two is recommended in some cases. THE REVERSERS ARE STILL THE KEY TO REDUCING BRAKE ENERGY ABSORBTION.

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