How not to cool down the brakes of an aeroplane (cardboard)

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luchtzak
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How not to cool down the brakes of an aeroplane (cardboard)

Post by luchtzak »

A strange procedure around the brakes of this Philippines AirAsia Airbus A320 (RP-C8979), a bunch of ground staff is cooling down the brakes with cardboard shortly after landing at a currently unknown airport.

Seems dangerous to me ....

https://www.aviation24.be/airlines/airas ... cardboard/

Poiu
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How to cool down the brakes of an aeroplane

Post by Poiu »

luchtzak wrote: 09 Jan 2018, 14:16 A strange procedure around the brakes of this Philippines AirAsia Airbus A320 (RP-C8979), a bunch of ground staff is cooling down the brakes with cardboard shortly after landing at a currently unknown airport.

Seems dangerous to me ....
Why would this be dangerous?
Never heard the load noise of the brake fans during turnarounds? These people are just manual brake fans.
There is a big margin between the max brake temp for TO and the danger zone.

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luchtzak
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Re: Trivia 2018 (miscellaneous news)

Post by luchtzak »

Poiu wrote: 09 Jan 2018, 14:34
luchtzak wrote: 09 Jan 2018, 14:16 A strange procedure around the brakes of this Philippines AirAsia Airbus A320 (RP-C8979), a bunch of ground staff is cooling down the brakes with cardboard shortly after landing at a currently unknown airport.

Seems dangerous to me ....
Why would this be dangerous?
Never heard the load noise of the brake fans during turnarounds? These people are just manual brake fans.
There is a big margin between the max brake temp for TO and the danger zone.
And if the thing explodes ?

Steve W.H. comments that the applied procedure can be very dangerous for people standing next to the brakes: “doesn’t anyone there realize that hot brakes can lead to a magnesium wheel explosion, not a pretty site when all the shrapnel takes many of that fan brigade out!!!…”

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KriVa
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Re: Trivia 2018 (miscellaneous news)

Post by KriVa »

Why would the thing explode? As said, there's quite a large margin between "safe for take-off" or "danger of exploding".
Also, if the temperature were anywhere near the danger zone, fanning the brakes with some cardboard wouldn't really make any appreciable difference to the temperature.
My guess would be that, according to the manual, they need to have a brake cool down period of, let's say, 45 minutes, while the actual turn-around is calculated to be in the 35-40 minute mark. Then this kind of procedure might make a difference, though it would be better to use an actual fan, I think.
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Re: Trivia 2018 (miscellaneous news)

Post by Homo Aeroportus »

Poiu wrote: 09 Jan 2018, 14:34
Why would this be dangerous?
Never heard the load noise of the brake fans during turnarounds? .....
Not all are equipped with brake fans.
This is an option on A320s.

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Re: Trivia 2018 (miscellaneous news)

Post by Homo Aeroportus »

Short turnaround time may create a problem with brakes not having enough time to cool down before the next departure. One must consider the need to use the brakes to their full capacity in case of an RTO.

Graphic representation of the bake temp during a "normal day in the office".
6-24-2013-9-03-16-AM.jpg
Courtesy Airbus.

H.A.

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Re: Trivia 2018 (miscellaneous news)

Post by Homo Aeroportus »

I don't want to substitute myself to member TomPompier but the access to the main landing gear is very critical and a controlled process for the Fire Brigade.

Never ever approach straight into the axle, this is the most dangerous area in case of explosion of the wheel.

Abstract from Boeing ARFF presentation.
tire_safety_area.jpg
Not good either to position yourself in front or rear of the tyre or you risk facing a flying piece of rubber straight to your face.

The correct approach is at 45° angle and by all means, let the Pros handle this. They will, if necessary, water mist the gear assembly as extinguishers or flows of water risk creating a shock cooling with dangerous consequences.

H.A.

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KriVa
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Re: Trivia 2018 (miscellaneous news)

Post by KriVa »

Sure, but do consider the difference between hot brakes for cockpit crew and hot brakes for ARFF crew.
When cockpit crew talks about hot brakes, they look at it from a performance standpoint, those same hot brakes would be regarded as lukewarm for ARFF crew, and not even close to approaching the danger zone.
Without more parameters (what temperature was the gear actually at?), this discussion is pretty much moot.
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Re: Trivia 2018 (miscellaneous news)

Post by Bracebrace »

Homo Aeroportus wrote: 09 Jan 2018, 15:47 I don't want to substitute myself to member TomPompier but the access to the main landing gear is very critical and a controlled process for the Fire Brigade.
Good! No more walkarounds for me ;)

As said, there is a huge difference between "too hot to handle taxi and a reject on next takeoff" and the caution zone...

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Re: Trivia 2018 (miscellaneous news)

Post by Homo Aeroportus »

Bracebrace wrote: 10 Jan 2018, 07:56 ....

As said, there is a huge difference between "too hot to handle taxi and a reject on next takeoff" and the caution zone...
Agreed that the ECAM WHEELS page indicates the temp of the brakes and therefore the tyres will be at a lower temp, but is it safe?
On Airbus the BRAKE HOT comes on when at least one of the brakes is at or above 300°C, so your guess is as good, most probably better, than mine as to the actual temp of the tyre. But what you don't know is if the tyre is in a good shape, able to withstand the 12-14 bar pressure at that unknown high temperature. Worn out or damaged tyres are subject to burst which is often unexpected because there is no fuse to melt due to "hot" temp.

Talking about walk around, it is also good to stay clear off the boarding bridge wheels.
As you know these are often aircraft wheels, pumped up to about 15 bars. They are not subject to high temps but they live a terrible life carrying +30 tons and being constantly manoeuvred in screeching tight corners.
It happens too often that a ground personnel is victim of a tyre explosion, some being deadly accidents.
Reason why a number of airports have invested in "solid" tyres, made of plain rubber. BAC has done that.

H.A.

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