Landing gear still down after takeoff?

[INTHEOUTBACK]

Just a quick question, today at work i watched as a finnair 753 tookoff but seemed to leave the gear down for quite sometime (it was still down when I lost sight of it). I also witnessed the same thing happen on a BA 320, again the gear was still down when I lost sight of it:confused:. Both a/c carried on and never returned to the field so i'm assuming it was'nt a technical problem. In both situations T/O appeared 'normal' and A/C had no problem climbing, both a/c were'nt going slow either. Someone out there has to know the answer.:ok:

[AlphaWhiskyRomeo]

Probably letting the brakes cool before popping the gear in the bays.

Brakes will easily overheat in this weather with lots of stop-start taxiing.

Have noticed it a bit out of MAN recently.

[hetfield]

Yeah, another reason might be that most aircraft have an inflight braking system. Means before the dunlops move in their houses the wheel spin is stopped. If a failure of this system occurs (e.g. wheel tacho) dunlops have to remain down for 1-2 minutes until rotation stops and retraction can start.

[underread east]

Or a brake line disconnected...Again usually brake system normally stops wheel rotation after take off, but with a brake brake disconnected gear must be left down until wheel stops spinning before raising the gear. I fly 757-200 which requires 2 minutes gear down after take off for this - plus a significant max weight reduction (in region of 14 tonnes) for the lack of 1 brake.

[sixmilehighclub]

With A320s, I'm with ASR on this one for the most likely reason. Some are prone to overheating brakes. Most A320s use a brake fan after landing to cool them down. The older models of A320 dont have this kit. BA have both the old and new series.

So following TO if the warning goes off or the temp is seen as high, they leave the gear dangling to ensure adequate cooling before retracting it.

This can cause quite rigourous vibration in the cabin but is completely safe and if necessary, a lower height will be maintained until retraction of the gear takes place to allow safe ascent.

[chadwick]

Probably letting the brakes cool before popping the gear in the bays.
How about just plain forgetting. Happened to a 76 crew about 6 years ago and left them down with parasitic D until they reached the west coast of Ireland! The words from the engineers on the RT were amusing if not colourful, to those who listened in on company RT it was hysterical to hear pathetic excuses once tech issues were ruled out!

[Packsonflight]

Or maby they simply forgot the gearpins!!!

[Kestrel_909]

Heathrow Director has a post on here somewhere (no really, he does!) I read sometime ago and still remember.

I can't remember the situation, but was along the lines of telling a departing Air France aicraft his gear was still down, and the response was 'Affirm, we use it for take-off.'' :}

[West Coast]

Could possibly be due to a MEL requiring it. Some aircraft can have the overheat loop(s) for the gear deferred. The MEL requirement is that the gear remain down for a prescribed period of time after T/O to ensure no hot brakes.

[Human Factor]

All good suggestions. Another possibility is the nose-wheel snubbers in the nose bay are u/s so the nose-wheel needs to spin down before it retracts.

[B Fraser]

Another possibility is the nose-wheel snubbers in the nose bay are u/s so the nose-wheel needs to spin down before it retracts.

Why's that old chum ? If the nosegear retracted sideways a la Trident then the gyroscopic forces would be significant however if the nosegear retracts fore /aft while the wheels maintain their direction in space then the turning moment is zero. :8

I have my spoon waiting if I deserve a slice of humble pie

[BOAC]

No 'humble pie' but it is better not to have a wheel rotating at Nx100 RPM in the bay.

Such a defect does, of course, degrade your performance for take-off since the gear remains down.

[Human Factor]

Careful, Mr F.
In my company we try to avoid using the T-word. It often triggers a very dangerous response along the lines of:

"I remember when I was on Tridents, we used to descend at 20000ft/min and do Mach .92 to the Outer Marker and ....."

:} :} :} :}


Out of interest, on the 777 it reduces the performance limited take-off weight to around 220 tonnes from the usual 270 ish. :eek:

[B Fraser]

I have a set of T3 manuals that show how to do it too, lots of warnings about descending the cabin first so the outside does not overtake the inside.

anyway, I digress.....