Cooling brakes with water as a normal procedure
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Cooling brakes with water as a normal procedure
Was just reading an article about brakes and the fellow writing it said "the
procedure that JAL (Japan Air Lines) routinely used for cooling the brakes of their 727s, DC8s and 747s with water. This caused immense steam clouds."
The article is a bit dated. Is this something that is still done. Have never heard of it or seen it done.
procedure that JAL (Japan Air Lines) routinely used for cooling the brakes of their 727s, DC8s and 747s with water. This caused immense steam clouds."
The article is a bit dated. Is this something that is still done. Have never heard of it or seen it done.
Last edited by JammedStab; 18th Oct 2013 at 08:15.
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Never seen it done here in the UK. The airbus has brake fans which is a good invention.
I'd have thought it to be a pretty bad idea due to the steam (and risk of it burning you!), heat shock on the materials and the fact tyres would be hot as well. Obviously depends on how cold the water is but still I wouldn't really do it.
I'd have thought it to be a pretty bad idea due to the steam (and risk of it burning you!), heat shock on the materials and the fact tyres would be hot as well. Obviously depends on how cold the water is but still I wouldn't really do it.
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You can always argue that brake cooling is not required...
Heard that too many times in my career on the flight deck. I guess if superiors and/or trainers promulgate that message enough it MUST be true, right?
Heard that too many times in my career on the flight deck. I guess if superiors and/or trainers promulgate that message enough it MUST be true, right?
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Jammed,
I dont think that happens any longer, and would be surprised if that was even allowed back in the day.
If one looks at the properties of steel, heating and rapid quenching creates a hardening (brittle) surface that one would not want on a brake surface..
If this was in efect today, with a ceramic disk, it is likely to fragment...
I dont think that happens any longer, and would be surprised if that was even allowed back in the day.
If one looks at the properties of steel, heating and rapid quenching creates a hardening (brittle) surface that one would not want on a brake surface..
If this was in efect today, with a ceramic disk, it is likely to fragment...
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@ latetonite, sir may be i fly small turbo prop atr thats why we use it mostly to avoid keeping our engine running.. i fly in southasia and we also utilize it at sharjah etc.. n i m not talking about brake cooling fans like airbus has em. besides the fact that our brakes normally cool within the turnaround time but at times this technique had also been used.. n here we are disscussing if its practical to cool brakes with blown air or water etc. if they (ac vans) were not around over the parking stands then i wouldnt have said it.
Brake cooling with water
Prior to the opening of the current international terminal in Brisbane, the distance from the old terminal o the runway (particularly the RW19 threshold, about 8 km) was such that brake temperatures could become an issue.
A solution to this was to taxi through a low spot on the taxiway (L as I recall) where water lay to provide brake cooling. The advantage was that because the wheels and discs were turning as they went through this water, there was no tendency to warp discs.
A solution to this was to taxi through a low spot on the taxiway (L as I recall) where water lay to provide brake cooling. The advantage was that because the wheels and discs were turning as they went through this water, there was no tendency to warp discs.
When Boeing is doing high-speed taxi tests (i.e. prior to first flight of a new model) they pull off and cool the brakes with fans (not sure if there is active "a/c" style cooling - it's always been well in the distance when I watched). Never heard of them using water to cool the brakes.
Most of the current production Boeing aircraft use carbon/carbon brakes (weight savings and longer life compared to steel) - I've not heard that carbon brakes have issues with rapid cooling. I'm unaware of ceramic brakes being certified for commercial aircraft use.
Most of the current production Boeing aircraft use carbon/carbon brakes (weight savings and longer life compared to steel) - I've not heard that carbon brakes have issues with rapid cooling. I'm unaware of ceramic brakes being certified for commercial aircraft use.
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Carbon brakes absorb water which can freeze at altitude causing locked wheels and blown tires during landing. Never spray water onto carbon brakes.
One report: http://www.skybrary.aero/bookshelf/books/1359.pdf
One report: http://www.skybrary.aero/bookshelf/books/1359.pdf
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Carbon brakes absorb water which can freeze at altitude causing locked wheels and blown tires during landing. Never spray water onto carbon brakes.
One report: http://www.skybrary.aero/bookshelf/books/1359.pdf
One report: http://www.skybrary.aero/bookshelf/books/1359.pdf
From the ATR-72 manual: "SPECIAL CASE
If contaminant layer is significant enough to possibly accumulate in the
brake area during ground operation, brake disks may join due to icing
during the flight, leading to possible tire damage at subsequent landing.
The following special procedure should be applied during taxi before and
as close as possible to take off.
Set 18% Torque on each engine and keep taxi speed down to a "man
pace" during 30 seconds using normal brakes with minimum use of nose
wheel steering to ensure a symmetrical warming up of the brakes."
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Seen brakes cooled with water in the old Eastern block countries on occasion. Never liked the idea myself, shock cooling and all the rest of it.
The best way to not to have the brakes heat up in the first instance, apart from excessive braking during the landing run. On a long taxi, IIMO was to shut down the 2 outer engines after a cooling period. It is the constant use of the brakes after landing, when the aircraft is light that caused a lot of the trouble.
The big airports in KSA you had to be careful as there were long taxis.
The best way to not to have the brakes heat up in the first instance, apart from excessive braking during the landing run. On a long taxi, IIMO was to shut down the 2 outer engines after a cooling period. It is the constant use of the brakes after landing, when the aircraft is light that caused a lot of the trouble.
The big airports in KSA you had to be careful as there were long taxis.
Last edited by Don_Apron; 19th Oct 2013 at 08:47.
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Cooling brakes with water is not an acceptable practice - it can cause distortion and cracking of wheels as well as damage to brakes. Boeing with regard to brake cooling on 747s states that a fine mist of water may be used for cooling but not hoses or as I have seen ,buckets of water being thrown over brakes - this causes thermal shock. AC trucks can provide ambient air for brake cooling but usually there is only one provided so it is time consuming.The best I have seen was at the old Bangkok airport -Don Maung - where individual fans driven by small Honda motors could be positioned at each wheel to suck air through the brake units - very effective. The were brought by the handling company on a trailer but as there were only 8 units they had to be swapped around on a 16 wheel 747. Used them a couple of times when Flight Mech on heavy 747s and was impressed. Never seen such equipment anywhere else.
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I had also heard in the past that the high temps could split the water into hydrogen and oxygen. A dangerous situation. However having just looked it up, I see that that only starts to occur at 2200 deg C. Don't think I will be getting my brakes that hot!