Smoky main gear?

[Erik H. Bakke]

While sorting through some of my photos from the last couple of years, I noticed one of VH-QPH on takeoff from Sydney.
This was a 4-shot sequence of the aircraft taking off, and on the last one I noticed smoke that appears to come from the main gear.

Anyone know why this would be, and why it would only show this late?
448

[Seth Jaworski]

It's brake dust.

[Anthony J]

While sorting through some of my photos from the last couple of years, I noticed one of VH-QPH on takeoff from Sydney.
This was a 4-shot sequence of the aircraft taking off, and on the last one I noticed smoke that appears to come from the main gear.

Anyone know why this would be, and why it would only show this late?
448
Seth is spot on.

During gear retraction the brakes are applied to stop wheel rotation and subsequent damaging gyroscopic force. On smaller aircraft this is done by the pilot, on larger aircraft it is an automatic function of retracting the gear.

[Erik H. Bakke]

Thanks, that explains it perfectly.

What you can learn on here, it'll never stop to amaze me.

[Tim Bowrey]

Seth is spot on.

During gear retraction the brakes are applied to stop wheel rotation and subsequent damaging gyroscopic force. On smaller aircraft this is done by the pilot, on larger aircraft it is an automatic function of retracting the gear.

Hey AJ.

I have seen this a fair bit but i've noticed that the main aircraft that do it are the A330's and the odd A340. I have never seen any 74's or 76's use the breaks on climbout. Do the Boeings do it?

http://www.jetphotos.net/viewphoto.php?id=6384113&nseq=0

Cheers

[Anthony J]

Hey AJ.

I have seen this a fair bit but i've noticed that the main aircraft that do it are the A330's and the odd A340. I have never seen any 74's or 76's use the breaks on climbout. Do the Boeings do it?

http://www.jetphotos.net/viewphoto.php?id=6384113&nseq=0

Cheers

They sure do. From the B767 FCOM:
Landing Gear Retraction
When the landing gear lever is positioned to UP, the landing gear begins to retract.
The landing gear doors open and the main gear wheels tilt to the retract position.
Automatic wheel braking occurs during gear retraction.

[Krzysztof M]

Speaking of wheels, a few weeks ago I saw the -OGF take off from 34L and the left bogie didnt retract until long after departure. Is that perfectly normal? Never seen that before, here are two pics:

http://i320.photobucket.com/albums/nn327/N495QS/Aviation/VHOGFJan144700.jpg

http://i320.photobucket.com/albums/nn327/N495QS/Aviation/VHOGFJan145700.jpg

[Brenden S]

Appears to be the sequence valve didn't work.

[Anthony J]

That would be a dispatch with the Centre Hydraulic System Air Demand Pump inoperative.

The ADP operates to supplement the electric pumps during high demand, especially gear operation.

It is perfectly acceptable hoever the slower gear retraction time leads to a performance penalty. Often one leg is left dangling until the others are up (most often the nose gear).

[NickN]

Actually Tims post made me think, I have probably 100 Airbus images (A330 & A340) with brake dust clearly visible yet I can only recall maybe 1 or 2 Boeing shots with the same thing. Do the Airbus models apply the brakes faster which causes more grit to be dislodged vs. Boeing?

[Nigel C]

Different brake compound perhaps?

[NickN]

Perhaps even a completely different brake system design?

[Krzysztof M]

Thanks Brenden and AJ. Amazing how once explained things suddenly make sens.

[Raymond Rowe]

Alot of airbus brakes are carbon fibre. shocking things to go near when not working with gloves.

[Brenden S]

Carbon vs Steel brakes, however Boeing have carbon brakes, all depends on the operator and also the type of brake installed on the aircraft. Airbus are notorious for carbon dust.