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What Is The Black Smoke Coming Down From The Gears  
User currently offlineRed Panda From Hong Kong, joined Jun 2000, 1521 posts, RR: 0
Posted (10 years 10 months 4 weeks 22 hours ago) and read 2828 times:


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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

9 replies: All unread, jump to last
 
User currently offlineAJ From Australia, joined Nov 1999, 2386 posts, RR: 24
Reply 1, posted (10 years 10 months 4 weeks 21 hours ago) and read 2789 times:

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!


User currently offlineJBirdAV8r From United States of America, joined Jun 2001, 4488 posts, RR: 22
Reply 2, posted (10 years 10 months 4 weeks 21 hours ago) and read 2748 times:

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
User currently offlineAA737-823 From United States of America, joined Mar 2000, 5722 posts, RR: 11
Reply 3, posted (10 years 10 months 4 weeks 21 hours ago) and read 2734 times:

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


User currently offlineAJ From Australia, joined Nov 1999, 2386 posts, RR: 24
Reply 4, posted (10 years 10 months 3 weeks 6 days 23 hours ago) and read 2555 times:

Another example:

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User currently offlineBronko From United States of America, joined Jul 2001, 810 posts, RR: 11
Reply 5, posted (10 years 10 months 3 weeks 6 days 22 hours ago) and read 2519 times:

So why is this not seen on a regular basis? Does this only happen on a visible level when the breaks are new?


Jet City Aviation Photography
User currently offlineJwenting From Netherlands, joined Apr 2001, 10213 posts, RR: 19
Reply 6, posted (10 years 10 months 3 weeks 6 days 22 hours ago) and read 2492 times:

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
User currently offlineFlyingbronco05 From United States of America, joined May 2002, 3840 posts, RR: 2
Reply 7, posted (10 years 10 months 3 weeks 6 days 22 hours ago) and read 2449 times:

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

Do a search Smile

fb05



Never Trust Your Fuel Gauge
User currently offlineDc10guy From United States of America, joined Feb 2000, 2685 posts, RR: 6
Reply 8, posted (10 years 10 months 3 weeks 6 days 21 hours ago) and read 2410 times:

You will see this on aircraft with "carbon brakes" .


Next time try the old "dirty Sanchez" She'll love it !!!
User currently offlineBio15 From Colombia, joined Mar 2001, 1089 posts, RR: 7
Reply 9, posted (10 years 10 months 3 weeks 6 days 11 hours ago) and read 2265 times:

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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