B737-800 brake cooling schedule
 

After a high speed rejected take off and setting the parking brake, can you just vacate the runway and set the parking brake again even if the brake cooling schedule says it needs few hrs? (Yes, I know the runway will be closed anyway until it get inspected but I was just wondering)

After a reject on 7378 you do not set the parking brake
If you do an evacuation ( follow QRH) then you set the parking brake

As written above,you do not set the parking beake until /if the decision is made to evacuate.
If you have steel brakes(check your AFM)following a brake limit energy stop (check your perf table) then good luck trying to taxi anyways,might as well call for a 'cab':E

Setting the Park Brake yes/no is a company SOP. I've flown for airlines that use both philosophies. The 'set park brake' SOP is approved by the XAA & Boeing, I assume.

This is not a discussion of right or wrong, just what happens.

Hmmm. Boeing just says "Consider" not setting the parking brake. But even then there is no justification of why. Why?

with the parking brake set the brake pads will takes more longer to cool down.

True.i believe ryan air uses the parking brake as their sop.
I guess ryan air has carbon brakes fitted in most if not all their -800s?

Thanks fulminn,

I was sort of expecting the answer to be brake binding or something. I have to ask, what is the pressing issue with cooling duration after a high speed RTO? One may as well assume the fuses will go sooner or later unless the cooling schedule says otherwise - when time allows.

BTW, caution and fuse plug melting becomes an issue with Carbon brakes at slightly lower energy levels than steel.

I'm thinking that when stationary, setting the parking brake would seem a pretty sensible and risk averse action. It is SOP at our place too.

No they don't.

Boeing SOP would recommend setting the brake as part of the RTO before getting around to assessing the problem causing the RTO. The alternative would be for you to stand on the brakes whilst making an evacuation decision, setting it then if not forgetting it (much more dangerous).

But, once the decision NOT to evacuate is taken, when taxied clear of the active runway, return to the cooling schedule guidelines and follow them, eg consider not setting your brakes.

I have often wondered about this. If it is just a cooling issue then in my mind setting the brake after the RTO would be prudent while assessing the situation. If there is a brake binding/welding issue then it may be better to stand on the brakes but I have found no mention of binding or welding anywhere so I plan to set the park brake when the aircraft stops. Can anyone provide a reference to binding being a concern?

subjective really,an aircraft that is stopped does not require much braking force if any at all and should not drain any captain brain energy away from an evacuation decision..
For the 'forgetting ' issue refer to the Evacuation CHECKlist.


One other difference between carbon and steel brakes that might be evident in certain RTOs is brake welding. Steel brakes, which usually have rotors of steel and stators of a copper-iron mix (with a number of special ingredients) can weld together, preventing further wheel rotation. This can even happen before the airplane comes to a full stop, particularly in the last several knots where the antiskid system is not effective.

I would be keen on more info about that de facto, can you remember where you learnt it? We have steel brakes and no guidance on the subject.
Cheers

Of course,google "take off safety guide" you should find the document.
If you cant ill have a look in my files when i get home.

That's a great doc although Mrs Framer would rather discuss the days events.
Ta.

Try "Pilot guide to takeoff safety" FAA work.:p

After a rejected t/o with steel brakes you really do not want to set parking brakes if it can be avoided.I once had to recover an A300-600 that had a rejected t/o and the brakes were welded on. We did not have enough brake units so we could not clear the aircraft from the runway.The result was a runway closed for hours until we flew some brakes in - fortunately another runway was available. Just to compound the problem we did not have 8 wheels either!

Have a look at this PDF document from 2003 produced by Boeing, I'd suggest...

It explains very carefully the risks and reasons behind Brake Cooling and its importance, with references t brake wear pin, welding, comparing carbon vs steel and much more. Interesting is also the graph showing temperatures of brakes, measure temperature of brakes and nitrogen over time.

I still need clarification. Assuming an SOP that require a parking brake set after an RTO on the runway. If evacuation is not required you will vacate the runway and check the brake cooling schedule. My question here is, in this case how would you stop the aircraft again after clearing the runway?

Would you not only check the cooling schedule if you intended an immediate 2nd attempt. If the failure required engineering inspection/action then it is a moot point.

Please correct me if I have the wrong impression wof, but you seem to be approaching his from the point of view that after the RTO, and possibly exceeding the brake limits, that the brakes won't work at all subsequently. They will, they simply won't have the efficiency you expect. Setting aside the welding issue and a subsequent take off scenario, you should be able to exit the runway, and still be able to stop the aircraft from a slow taxi speed. The brakes don't simply stop operating at all.