787 Dreamliner late undercarriage retraction

[wub]

I live close to Edinburgh Airport where there is a daily Qatar 787 service to Doha. I have noticed that occasionally the aircraft does not retract its gear right after takeoff but will leave it until it is well over 4,000 feet and several miles from the airport. Does anyone know why this happens, is it 787 SOP for cooling?

[HEATHROW DIRECTOR]

Cooling brakes and can happen with any type.

[wub]

Thank you, thought as much but never seen it at EDI on anything but the 787.

[HEATHROW DIRECTOR]

Happened to me years ago with an Air France A310. AS it climbed away I said "You still have the gear down"...... "Affirmative, we use it for ze take-off". I never lived that down.

[Green Guard]

They are from Qatar
so its not b'cos hot brakes after TO in Edinburgh but because "home habits"

[El Bunto]

On early 787s the wizzo-magic brake & tyre pressure monitoring system ( mounted on the gear ) often overheated, forcing operators to resort to the old-school technique of dangling the gear in the airstream since they didn't know how hot the brakes were...

Are Qatar 787s early-builds?

[MarcJF]

Why would the brakes be hot after departure?

[Hotel Tango]

From the sometimes frequent braking during taxy from terminal to runway.

[greybeard]

It could be an anti-skid fault which may prevent the brakes being applied during retract.
So you let the wheels spin down before retracting them.

3+ minutes on the older A-310

:confused:

[DaveReidUK]

It could be an anti-skid fault which may prevent the brakes being applied during retract.
So you let the wheels spin down before retracting them.

3+ minutes on the older A-310

Three minutes for the wheels to spin down ?

You're having a laugh.

[dixi188]

A300B-4 was 1 min. if anti-skid fault. Same for 1 brake inop.
Don't know why the A310 would be any different.

[AndoniP]

I'd assume that if you follow the departure speed on flightradar or whatever it'll show that being below VLO, then speed up after gear is up

[One Outsider]

Is the Pope catholic? Do bears **** in the woods?

But hey, you got to show you know about VLO.

[asw28-866]

'VLO', didn't they have a hit with 'Don't Bring Me Down' in the 70's? Rather appropriate really :}

'866

[AndoniP]

But hey, you got to show you know about VLO.

That's what I crave when I post on internet forums, recognition *has made it finally*

[Chesty Morgan]

Yeah but you could go up to Vle to accelerate the cooling then reduce to below VLo before you increase to Vne.

[Flying Fred]

It's probably got a wheel brake deactivated because of a fault, which is allowed in the 787 Dispatch Deviations Guide (DDG)

From the 787 DDG:-

Wheel Brakes may be inoperative on one main landing gear wheel per truck provided (amongst other things) the inoperative brake is deactivated and after takeoff, the gear remains down for two minutes before retraction.

As part of the normal retraction sequence, the wheel brakes are applied to stop the wheels spinning before they enter the gear bay. If a brake is deactivated, the affected wheel cannot be braked so the gear is left down for 2 minutes to ensure the wheel has stopped spinning

FF

[One Outsider]

I doubt it was that kind of recognition you were looking for.

[AndoniP]

Yeah I don't think you quite got it.

[fujii]

DaveReid,
Three minutes for the wheels to spin down ?

You're having a laugh.


No laughing matter. If one wheel is still spinning, it's one hell of a massive gyroscope. The precessional forces would be pretty large.

[DaveReidUK]

No laughing matter. If one wheel is still spinning, it's one hell of a massive gyroscope. The precessional forces would be pretty large.It's not about gyroscopic forces or precession.

The laughable part is the suggestion that there is so little friction in a wheel bearing and a brake heat pack that it would allow a wheel to continue to whizz around for 3 minutes after it has ceased to have contact with the runway.

[Chesty Morgan]

Actually it is what it's about, in part.