737NG after RTO

[citizensun]

hi all,
i am reading the 737 QRH Recommended Brake Cooling Schedule,
there are some instructions below those diagrams.
and i have some questions here:
a. Add 1.0 million foot pounds per brake for each taxi mile.
is that mean we need add 1.0 million foot pounds energe when taxi ,no matter there is brake apply on the wheels?
b. after the RTO, if the brake get very hot , sometime we need to extent the gear after the takeoff for couple minutes, if we foget to do so ,is there any chance to generate the wheel well fire?

thanks ~

[cortilla]

as far as i understand it
a) yes
b) after a RTO event, you're not going to be taking off full stop untill the brakes are cool enough so that they'll work fully if you have another RTO. But if you did attempt the foolish (i.e. attempting another departure) and then were crazy enough to raise the gear straight away then yes a wheel well fire is a distinct possibility. I'm working on the assumption that you've rejected at speed and not just closed the thrust levers immediately after standing them up due say a config warning or something like that.

As usual i'm willing to stand corrected by those more experienced than myself.

[BOAC]

Like he says.
a. Add 1.0 million foot pounds per brake for each taxi mile. - well, you will inevitably be applying brakes in that mile but most of the heat comes from the flexing of the tyre.

[citizensun]

Add 1.0 million foot pounds per brake for each taxi mile
do we need to add that energe no matter we taxi by the airplane itself or tow by the tug?
and why do we need to apply the brake for taxi?
thanks!

[BOAC]

1) Have you ever taxied an aeroplane?
2) If you are behind a tug, go to the bar. You will not be flying that aeroplane again soon.

[citizensun]

i`ve been flying 737NG for 5 years so far which is not very long compared to so many experienced pilot in this site,
while taxing we do not apply the brake all the time unless we need to slow down, do we need to take the "no brake taxi mile" into the consideration?

[bArt2]

while taxing we do not apply the brake all the time

If you did, you would have to add a lot more I guess let alone ending up with hot brakes at the holding. Anyway these kind of additions are allways an estimation based on the average guy doing an average taxi on an average taxiway. Just add the damn thing and go on.

[PantLoad]

Taxiing, in and of itself...

Taxiing, in and of itself, creates heat in the tires....thereby transferring heat to the wheels (because the tires are attached to the wheels)....and, with hot wheels, brakes become hotter....because, when applied, brakes touch the wheels.... You get the idea.

There was an accident several years ago....can't remember....I'm thinking it was out of LAX....because the guys were taxiing a long distance, at high speeds, not following SOP with regard to brake use during taxi. (Can't really remember the details, so if I'm wrong, I'm sorry.)

The faster you taxi, the hotter the tires, therefore the hotter the wheels, therefore the hotter the brakes. This also goes for the farther you taxi.

Planes were made to fly, not taxi.

Anyway, I'm thinking they had one or more tire failures during takeoff, rejected the takeoff (usually a bad idea, depending on the speed at which all this happens)....couldn't stop (because they had fewer tires/brakes to stop them).....anyway, another statistical RTO accident.

All because they were heavy, taxied too fast, taxied too far, rode the brakes, rejected the takeoff because of tire failure....all mistakes.

(Well, how heavy there were wasn't their fault, neither was the distance they had to taxi....but, the rest of the mess was.)

So, the Boeing chart is correct. Follow it. If you don't understand, ask your friendly training department. That's what they're there for.


Fly safe,

PantLoad

[citizensun]

thank you all~~
" Just add the damn thing and go on"--- i like this!

now i know the idea why we take that "taxi mile thing" into consideration.
thanks~