Red Panda
Topic Author
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What Is The Black Smoke Coming Down From The Gears

Thu Aug 21, 2003 2:18 pm


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It is normal to have smoke coming out from the rubbers on landing, but what is that smoke falling down from the gear on takeoff?



r panda
 
AJ
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Joined: Wed Nov 03, 1999 3:54 pm

RE: What Is The Black Smoke Coming Down From The Gears

Thu Aug 21, 2003 2:22 pm

During the retraction cycle of the undercarriage the rotation of the wheels is stopped to prevent gyroscopic rotational forces. When the brakes are applied it can cause any excess grease/dirt etc. to burn off as the brakes are absorbing quite a bit of energy, iplus the heat absorbed during taxi.

You can imagine the stress the brakes would be under in a rejected takeoff!
 
JBirdAV8r
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RE: What Is The Black Smoke Coming Down From The Gears

Thu Aug 21, 2003 2:34 pm

It also stands to point out that the tires aren't smoking, but the brakes  Smile/happy/getting dizzy

As AJ already mentioned, I'd guess this particular airplane had a recent RTO or, perhaps, an extended taxi.
I got my head checked--by a jumbo jet
 
AA737-823
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RE: What Is The Black Smoke Coming Down From The Gears

Thu Aug 21, 2003 2:38 pm

Actually, my understanding is that, while both of the above explanations are correct, the actual stuff you see is carbon- because they're carbon brakes, not steel anymore. When the system 'steps' on the brake pedal during retraction, the wheels stop pretty quickly, producing a puff of black carbon powder from the braking surfaces.

R
 
AJ
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RE: What Is The Black Smoke Coming Down From The Gears

Fri Aug 22, 2003 12:46 pm

Another example:

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Bronko
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RE: What Is The Black Smoke Coming Down From The Gears

Fri Aug 22, 2003 1:18 pm

So why is this not seen on a regular basis? Does this only happen on a visible level when the breaks are new?
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jwenting
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RE: What Is The Black Smoke Coming Down From The Gears

Fri Aug 22, 2003 1:35 pm

It only happens when a lot of brake power is used during taxi or when putting on the brakes before gear retraction.
It might also have to do with environmental conditions (if there's a lot of wind the stuff would probably disperse quickly so you don't see it for example).

Personally I've never really noticed it.
I wish I were flying
 
flyingbronco05
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RE: What Is The Black Smoke Coming Down From The Gears

Fri Aug 22, 2003 1:57 pm

This has been discussed multiple times in the tech/ops forum.

Do a search Smile

fb05
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DC10GUY
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RE: What Is The Black Smoke Coming Down From The Gears

Fri Aug 22, 2003 2:19 pm

You will see this on aircraft with "carbon brakes" .
Next time try the old "dirty Sanchez" She'll love it !!!
 
bio15
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RE: What Is The Black Smoke Coming Down From The Gears

Sat Aug 23, 2003 12:47 am

AJ: I'm probably not very familiar with the subject, but I always thought that the stopping of the rotating wheels was to prevent further damage given a tire blowout during retraction inside the bay. Is that correct?


-Alfredo

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