Chi-town
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Question About Picture Of The Day

Mon Jan 19, 2004 5:07 am


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That right tire in the picture looks extremely bald. Shouldn't the airline have changed that tire by now? Also, I see that the left two tires still have some traction left on them. Why do these two still have traction and the right ones look bald?
 
meister808
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RE: Question About Picture Of The Day

Mon Jan 19, 2004 5:17 am

I think the outboard tires are different entirely. It looks like they may have been slicks. I know that they are different just by looking at the sidewalls.. they are different. So, they may not be too worn, just different. However, I don't really understand the benefit of putting tires with no tread depth on an airplane... how do they expect to stop on wet surfaces?

Also: Why the heck are they spraying water on hot brakes??? I am pretty certain that rapidly cooling metal parts like that can lead to stress fractures and ultimate failure of the part, which isn't too awful desirable on an airplane.

-Meister
Twin Cessna 812 Victor, Minneapolis Center, we observe your operation in the immediate vicinity of extreme precipitation
 
saintsman
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RE: Question About Picture Of The Day

Mon Jan 19, 2004 5:34 am

Water on hot brakes is a definate no-no. Try that and you run the risk of them shattering. Dry powder is the prefered medium, though you can use CO2 as a last resort if you bounce the spray off the ground first (so that all the cold is left on the floor).

 
744rules
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RE: Question About Picture Of The Day

Mon Jan 19, 2004 6:08 am

If you tell those crews they should replace the tires, most probably the answer will be : yes yes isa no problem !!
 
sushka
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RE: Question About Picture Of The Day

Mon Jan 19, 2004 6:09 am

Every time I fly on a Russian airliner I notice the tires. Most of the time threads are showing and they are completely bald. At least they have more tires than western planes. Still it is sad.  Sad

[Edited 2004-01-18 22:15:31]
Pershoyu Spravoyu Litaki!
 
air2gxs
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RE: Question About Picture Of The Day

Mon Jan 19, 2004 6:44 am

As far as I know, transport aircraft do not use slicks. The tire visible is worn, but I also see no damage (ply exposed, cuts to the cord, etc). Granted this tire would be have probably been replaced before now at any of the airlines I've worked with. This is to save the carcass for re-tread. Some airlines may fly the tire until they have no life left in them, who knows.
 
jutes85
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RE: Question About Picture Of The Day

Mon Jan 19, 2004 12:33 pm

What else would you expect from a Ukrainian Airline.
nothing
 
SlamClick
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RE: Question About Picture Of The Day

Mon Jan 19, 2004 12:54 pm

Don't know what standards would apply for a Ukranian plane operating in the Congo but in the USA, the wear standards allow for a tire as bald as that one as long as the cord showing does not exceed a certain fraction of the circumference. The tires are recapped a limited number of times then retired. Any mechanics out there, jump in on that.

Second:

Common misconception to think that it would be bad to spray water on hot brakes. It is pefectly okay, if done right.

Think about it - if a little water on a hot brake would shatter metal, then you could never land an airplane on a wet runway. You could never take off with hot brakes and allow them to fly through rain. And there would be shattered brakes all over the northeast United States at this very moment because it is cold and slushy up there.

It is actually a fairly common practice to cool brakes with water. It us normally done with a little mist, rather than a firehose spray, but it carries heat away quite well.

Happiness is not seeing another trite Ste. Maarten photo all week long.
 
RNOcommctr
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RE: Question About Picture Of The Day

Mon Jan 19, 2004 2:55 pm

When I first started working at RNO in 1980, the fire department cooled hot brakes with big ventilating fans. They don't do this anymore. Now their policy is to just stand by as the brakes cool on their own. Anyone know anything more about this?
Active loading only, ma'am, keep it moving!
 
air2gxs
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Joined: Mon Jun 18, 2001 1:29 pm

RE: Question About Picture Of The Day

Mon Jan 19, 2004 10:52 pm

I believe you can re-cap a tire as long as the carcass is servicable. I seem to remeber that tires have markings on them that denote the amount of re-caps. I've only built uop 2 wheel assys. and that 16 years ago with DAL at LGA when 1 of the tire guys called in and I was junior. But, I remember him talking about those markings.
 
SlamClick
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RE: Question About Picture Of The Day

Mon Jan 19, 2004 11:17 pm

RNOcommctr

Yeah, fans do it too, anything that will carry heat away. Brakes stop airplanes by converting kinetic energy to heat. Must remove that excess heat or they do not have the stopping power for a rejected takeoff. Water works better but it is really not done all that often. The fire department might have done that to keep the fuse plugs from letting go. Kind of risky even to approach an overheated wheel.

At RNO it is probably more important not to brake too hard or too early, but to let it roll to the far end. That way you don't get the buildup in the first place.

Leaving the parking brake set with high brake temps is a bad idea. First, they don't cool as quickly when they are all bound together like that and second, if they are hot enough, they can "weld" the rotors to the pucks.
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
MD11Engineer
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RE: Question About Picture Of The Day

Tue Jan 20, 2004 2:55 am

You can use a water mist to cool down the brakes to prevent the fuse plugs from blowing, but don´t use a sharp jet. Acc. to the GOM (General maintenance manual) of our company (FAA approved) we can have the first layer of thread reinforcement cords visible if it is not more than 45° of the wheel circumfence on a turnaround. There are usualytwo layers of thread reinforcement cords right under the threads, and theyare not to be confused with the carcasse plies, which are NOT permitted to be damaged. Sidewall damage is not permitted either. Aircraft tires are of a different design than car tires. A/C tires have to be able to accept shock loads, but don´t have to get a plane around curves at high speeds, and since they don´t propel the plane they don´t need that much traction. BTW, in the threaded area they are usualy 2-3 inches thick.

Jan
Je Suis Charlie et je suis Ahmet aussi

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