Cool brakes with water ?
 

The other day when I went for walk around check.I find some trace of water around brakes.I guess maintenance guy tried to lower brake's temperature.I wonder if this OK. although we have carbon brakes.

Most probably came from water condensing and dripping from the cold wings. Nobody throws water on hot brakes, they cool naturally.

WTF? Do you mean brakes? Or circuit breakers? If you were on a walk around then probly not unusual to see water around the wheel area. Comes from the underwing ice above your head.

Sorry capt, got me while I was typing....

What if someone poured water onto the brakes .I just wonder if that will cause damage to brakes.

Please use the word brake, it's quite clear that you are not talking about breakers.
On the other hand cooling breakers with a bucket of water would be quite interesting on an aircraft.

A brake stops the plane from rolling, for example the parking brake.

A breaker on the other hand is an electrical device to break electrical current.
Breakers prevent electrical fires by tripping if a device under load uses too much power.

This link seems relevant:
https://aviation.stackexchange.com/q...dle-hot-brakes

So apparently cooling with water mist is ok. And why wouldn't it be the aircraft operate in heavy rain sometimes. Granted that is not quite the same.

If you want to see what happens when you spray water onto hot brakes search Youtube for A340-600 RTO.

wiedehopf’s link suggests otherwise, but I would have thought that routine cooling of brakes by pouring water on them (to reduce turnaround times?) is a highly questionable, and potentially very dangerous practice. (The thermal shock could cause them at best to distort, at worst to violently blow apart. The chap shown in the link has no protective gear at all whereas the firemen in the other link do.)

If the OP is talking about a small amount of water dripping around the brakes and landing gear, that is from the melting ice formed on metal cooled during the cruise freezing the moisture out of the air during the final desent. In particular, the underside of the wing gathers ice - on Airbus, under the inner fuel tank area at the wing root.

The A340 RTO test explosions have nothing to do with water being sprayed. 2 tires go before anything was sprayed and the others on outer gear which did not receive any spray.

Seems its not uncommon to use water-cooling for brakes. I would have thought it was dangerous too, but engineers assured it was OK. Admittedly they were NOT super-hot but i didn't volunteer to watch! A330F in this instance. Required for shorter turn round.

Wouldn't be the the first time spelling errors cost lives. Gotta love the English language...

Who uses water cooling for brakes?. Every A330 operator i know has always used air.

Not that this is relevant to normal airplanes, but an interesting sidenote: the Skylon spaceplane design is supposed to have a tank of water to spray on the brakes during an RTO. If the takeoff is successful, it's jettisoned.

Racing trucks and rally cars, but can't imagine an aircraft doing it because of the weight?

Bit iffy if they are hot. The rapid contraction is not going to do them any favours. Try sticking a pint pot in the oven then pouring cold water into it. Actully don't

god forbid you land on a wet runway and get water on the brakes or taxi through large puddles....the brakes might shatter.

Ever been to Indonesia?

The brake disks are inside the wheel hubs and are generally shielded from spray.

During landing, YES
During water being prayed onto them at an angle, NO

Hence the quoted message from Airbus aforementioned in this treat: as it depends on the angle there is more contact, thus water mist at the correct angle is best as the risk of large quantities of water directly contacting the brake disks in any location at any time is significantly diminished thereby reducing the damage risk.

@ TransitCheck, how very condescending.

When landing on a wet runway, the brakes will gradually heat up while gradually being cooled by spray - if any reaches the brake packs that is.

That is different to landing, possibly on a hot dry day, taking the first high speed exit, (to save time), taxiing in perhaps on a long taxi route and then after a few minutes on stand when the brakes are very hot, suddenly pouring lots of water on them.

Quenching, i.e. very rapid cooling from a very hot state in a tank of water as used by blacksmiths, alters the structure of the metal they are working. Perhaps carbon brakes are not adversely affected by ‘quenching’, but I would not want to take the risk.

I have not seen this brake cooling "procedure” written anywhere in the A320, A321, or A330 manuals I have read. Perhaps it is allowable and is detailed in the engineer’s manuals, but it sounds very risky to me. Firemen have detailed procedures for dealing with brake fires safely because of the risk of flying debris. You won’t catch me doing it on a routine turnaround, even with training and protective gear.