B737-800 brake cooling schedule

[wof]

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)

[LindbergB767]

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

[de facto]

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

[RAT 5]

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.

[Kefuddle]

After a reject on 7378 you do not set the parking brake
Hmmm. Boeing just says "Consider" not setting the parking brake. But even then there is no justification of why. Why?

[fulminn]

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

[de facto]

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.


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?

[Kefuddle]

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.

[Skyjob]

I guess Ryanair has carbon brakes fitted in most if not all their -800s?

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.

[framer]

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?

[de facto]

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).
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.

[framer]

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

[de facto]

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.

[framer]

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

[de facto]

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

[bcgallacher]

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!

[Skyjob]

Have a look at this PDF document (https://www.google.co.uk/url?sa=t&rct=j&q=&esrc=s&source=web&cd=2&ved=0CDgQFjAB&url=http%3A%2F%2Fwww.smartcockpit.com%2Fdownload.php%3Fpath% 3Ddocs%2F%26file%3DBrake_Energy_Consideration_In_Flight_Oper ation.pdf&ei=u5drUpikK8Ta4ASr4ICABw&usg=AFQjCNGwlLBMicuLdXvb5D7xpbCLiibazw&sig2=o3O7NSftnxM_3QIarSrtSg&bvm=bv.55123115,d.bGE)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.

[wof]

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?

[RAT 5]

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.

[porch monkey]

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.

[wof]

porch monkey what you said is helpful indeed but I was really asking about the correct procedure there, a little confusing part between SOP and QRH. After an RTO and setting parking brakes to assess the situation (which is recommended by SOP), then after completing NNC and evacuation is not required..would you also *hold* and check the brake cooling schedule on the runway so you wont release the brakes and vacate and then apply it again? or you just vacate and *stop the aircraft* then check the brake cooling schedule?

[albertofdz]

Hey wot,

My personal opinion, is that, in this scenario Boeing will never tell you to do something or other, instead they tell you to consider setting the parking brake. (except for a passenger evacuation)

IE, they´re passing all of the decision making on to you (or your companies SOP´s). This may be for various reasons, amongst others, unless the cabin is fitted with a BTMS, Boeing is correct in assuming that you may indeed be making over or (worst case scenario) under calculations on your brake cooling schedules from the former flight, after all, we are humans and prone to mistake.

Personally, after an RTO where evacuation is not immediately obvious and necessary, my decision would be based on first of all requiring fire fighting personnel to visually check my brakes for fire/smoke…. (parking brakes off by the way), there is no need to rush anything after an RTO, take 5 seconds to asses what is going on.

If gear is considered safe, then I would vacate the runway. If I can´t, because breaks have welded, then I would start the APU, shutdown, request steps, towing equipment, and buses for the passengers. Also I would advise ground crew to set chocks on the nose gear only and keep well clear form the main gear. Then I would have no other option but to hand the airplane over to maintenance (still on the rwy, remember gear was safe, but I could not taxi)

If gear is safe, and I can taxi, then I would vacate, start the APU, shutdown in a close by spot (where i´m in nobodies way), but this time I would have the aircraft towed with pax on board. (I would avoid taxiing If I could), and have the fire squad escorting me (just in case).

If the gear are in flames, I would order an evacuation. Even though fire fighters are on the way, theres quite a bit of fuel just on top of the gear!

This is just my impression. Obviously, if you have SOP´s regarding this situation, follow them! I´m pretty sure that the guys who publish your SOP´s have thought this over thoroughly.

Finally, I think its great that you brought this up. Typically RTO´s are not practiced properly in the sim. The easy part of an RTO is the actual RTO itself… The hard part comes after the RTO…. Would should I do? Do I vacate? Do I set the parking brakes? Should I evacuate? What sort of assistance should I request????

Good on you my friend! By the way, great machine the 738 huh? !!!

Cheers

[Skyjob]

If no evacuation required, vacate the runway as this is then free to use for others.
Then when clear of runway and having determined whether a return to stand is required (after a high speed RTO probably so, also SOP may dictate you to do so), before setting brakes to park(!) check Brake Cooling Schedule arriving at position to leave brakes off when chocks are in place.