777 with gear down

[twinpratts]

Is it normal ops to keep the gear down after takeoff for an extended period of time? I saw what looked like a 777 in YYC with the gear extended til what looked like 1000ft.
An anomaly?

[ACAV8R]

No not "normal". Couple circumstances that come to mind are Contaminated runway (not likely in this case) or MEL condition. No biggey.

[Rockie]

As mentioned the gear is recommended to stay down for 30 seconds or so in the case of slush build-up, or through an MEL item like one brake de-activated to allow the wheel to spin down before bringing the gear up. But in this case it was probably the 330 the day before yesterday that had some problem or other and was doing a low pass for a looksee from the tower.

[kevind]

viewtopic.php?f=54&t=60336

[HavaJava]

Must have been a Seneca grad who keeps forgetting to raise the gear...after doing a few gear-down circuits in the Baron it ruins us for life! (Or that's what some people on this forum would have you believe)

[ClevelandSteamer]

I asked an A330 Captain a while ago about this I had noticed departing Dar Es Salaam some time ago. His answer was that they sometimes leave them down a little longer due to brake temperatures and using the airflow to cool them down.

[flying4dollars]

I asked an A330 Captain a while ago about this I had noticed departing Dar Es Salaam some time ago. His answer was that they sometimes leave them down a little longer due to brake temperatures and using the airflow to cool them down.

How much braking was being used during the take off run on that flight?

[yycflyguy]

None. There is no braking on the take off run but the brakes retain heat from the previous braking event (landing) and during the taxi there is braking which will heat them as well. It is better to allow them to cool extended then have to use them again in case of a quick return and have hot brakes that can lead to more serious scenarios.

[Rockie]

I've never seen a procedure or recommendation to leave the gear down for brake cooling. There is a limit (usually 300 degrees C) above which takeoff is prohibited. Below that limit you are good to go with no restriction or further procedure necessary or recommended.

The only time leaving the gear down is required or recommended is to blow contaminates like slush off, or to allow the wheel time to spin down in the event of one brake being deactivated. In the case of the Embraer there is no MEL relief to takeoff with a brake deactivated, but it does require the gear to be left down for 10 minutes in the case of a departure with one or more brake temp indicators inoperative, L/G bay fire detection is inoperative, and brake cooling charts have not been used. But that is precautionary only to ensure the brakes are cold since there is no brake temp indication or fire indication, and significant performance penalties must be applied.

[Starting 4]

Rockie,

So what you are saying is that you have seen a procedure for brake cooling. You clearly describe one in your MEL example!

[Rockie]

No, it's not to cool hot brakes. One temp indicator may be inoperative, and as long as the L/G bay fire detection works there is no restriction to takeoff. Two or more may be inoperative and as long as the fire detection works and you adhere to AOM brake cooling times there is no restriction to takeoff. Only if you cannot meet those conditions is it necessary to leave the gear down for ten minutes, and that is only to ensure there is no residual heat since an overheat cannot be detected.

It's a precaution in case the brakes are hot, not because they are hot. You could start the airplane on the runway after sitting for 12 hours at -30 and you would still have to comply with the requirement.

The B777 has no such procedure and takeoff is permitted unrestricted without brake temp indicators as long as brake cooling charts are consulted. Same with the 320/330 series. The 767 doesn't even require you to consult the brake cooling chart although it's a pretty good idea.

[Mooney21]

Here is another example for other heavies. You are on a turnaround and the main are still showing some residual heat. You have a long taxi at of near MTOW and the take off is long, Brake temp is approaching 200-250c and if you gear up immediately after TO, temp will continue to rise in the confinement of the wheelwells, so in order to prevent getting a high temp. warning, you wait a minute of two before raising the gears.

[Starting 4]

It comes down to semantics; you are clearly leaving the gear down to cool the brakes before retraction. They might be red hot or frozen solid, either way they are being cooled.

Your example could be defined as a procedure for cooling the brakes.

[Rockie]

It comes down to semantics; you are clearly leaving the gear down to cool the brakes before retraction. They might be red hot or frozen solid, either way they are being cooled.

Your example could be defined as a procedure for cooling the brakes.

OK. If you want to use those sematics you go ahead. Beats me how you can cool brakes that are already frozen though. The reason they're left down in this case is in the event a brake is dragged during the takeoff roll. There is no gear well fire detection so it's left down for ten minutes to eliminate the danger of an undetected wheel well fire, and there are significant performance penalties for doing so. If the fire warning works it's not an issue.

I was addressing the idea that people leave them down routinely to cool the brakes after an extended taxi or short turn around. It is not necessary and it is not recommended anywhere that I've seen. The only requirement is the temperature limit as I've already mentioned. Don't forget that the gear is already going to be in a 100-150 kt breeze for about 30 seconds even bringing the gear up immediately. In normal ops nothing more than that is required.