Early 747 Wing Gear
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From: cincinnati area
Early 747 Wing Gear
O.K., just having a discussion about various speed brake systems and someone mentioned that they thought early 747's had the ability to extend the wing gear only, possibly as a speed brake. That immediately reminded me of something I had forgotten. Growing up not far from ORD in Chicago, in the early 70's, we lived under what was a fairly commonly used traffic pattern for certain runway configurations, so on some days, we would have lots of traffic passing over the house, including a pretty good amount of 747's. I remembered that is was fairly common to see them flying with the wing gear only extended. I have also seen photos of the gear handle on early 74's with a wing gear only postion. So my question is, does anyone know what the purpose was of operation with the wing gear only extended? Was it actually some type of speed brake device? As I said, I just remebered this and know I'm very curious.
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From: Gold Coast
I don't think so, because if you want speed brakes there's a speed brake lever in the cockpit for you to use.
It is possible, however, to extend each gear individually by the alternate system. That's only for emergencies though.
It is possible, however, to extend each gear individually by the alternate system. That's only for emergencies though.
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From: OZ
That is correct. About 30 years ago the detent on the gear lever, labelled "wing gear only" as I recall it, was blanked off initially and completely removed shortly thereafter.
Think about the human factors here - "gear down", oh dear, I meant the lot as the aircraft nose settles onto the concrete. Besides, it was as noisy as all Hell in use.
Think about the human factors here - "gear down", oh dear, I meant the lot as the aircraft nose settles onto the concrete. Besides, it was as noisy as all Hell in use.
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From: Smogsville
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From: nowhere
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From: Hongkong
SOP
The 'gear lever to off' before full flap retraction-which if not no an SOP is still good practice-was to ensure that if you did inadvertently drop the wing gear placing the lever 'off' (going through off) giving extra drag, you weren't clean and still had some high lift device deployed especially at heavy weights. Been there done that!
S
See the photo-it's not difficult to cock-up.
S
See the photo-it's not difficult to cock-up.
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From: The Smaller Antipode
SMOC - thanks for the picture, brings back memories, and yes, we too had that configuration ( tho' not the 'tape' eng. instruments ) including the finger slicing bacon slicer blade that one had to move aside if performing an alternate gear raising procedure. It was there to stop the gear being raised if the trucks weren't level so that one didn't graunch the wheel well access by forcing an off centre gear up into the hole. ( I think ? memory ? ) If all was well the blade moved out of the way and let the gear handle go right up to the UP position.
I have no recollection of why we had the wing gear position, never used it. We had a procedure for landing with one wing gear not extended, but not a main gear. (IIRC)
I have no recollection of why we had the wing gear position, never used it. We had a procedure for landing with one wing gear not extended, but not a main gear. (IIRC)
Last edited by ExSp33db1rd; 30th April 2012 at 09:31.
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From: nowhere
Perhaps but no pilot following the aircraft limitations will have experienced this as the max gear speed is 180 knots. In other words, all three gear always extend at the same time during normal operations on a gravel equipped 737. Sounds like a way to damage the nosegear deflector.
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From: Here, there, and everywhere
Finally reading Handling The Big Jets and it is mentioned in the 747 section about using the wing gear as a speed brake. Also, if one wing gear won’t extend for landing, the other one is somehow retracted(not a procedure on the -400).
Also something called Throttle Bar Protection. A mechanical bar is placed behind the thrus levers at altitude to prevent selection of idle power on JT-9D engines that can cause surging. Therefore, a slow initial descent from cruise altitude. Which may be the reason why the wing gear was used as a speed brake with this function being removed soon after the throttle bar was no longer necessary.
Keep in mind that the gear really can still be used as a speed brake or for increased descent rate. Simply extend it once below gear extension speed. Obviously, more applicable for the lower levels but I have done this on more than one type. Can be good for airports where they are keeping you up high fairly close in and then planning on keeping you in tight for the visual.
Any pictures, especially of the throttle bar?
Also something called Throttle Bar Protection. A mechanical bar is placed behind the thrus levers at altitude to prevent selection of idle power on JT-9D engines that can cause surging. Therefore, a slow initial descent from cruise altitude. Which may be the reason why the wing gear was used as a speed brake with this function being removed soon after the throttle bar was no longer necessary.
Keep in mind that the gear really can still be used as a speed brake or for increased descent rate. Simply extend it once below gear extension speed. Obviously, more applicable for the lower levels but I have done this on more than one type. Can be good for airports where they are keeping you up high fairly close in and then planning on keeping you in tight for the visual.
Any pictures, especially of the throttle bar?
Last edited by punkalouver; 5th December 2024 at 10:30.
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From: OZ
Punka
The wing gear as speed brake on B747 Classic series was disabled decades ago. I used it a few times - as noisy as hell. In the event one wing gear fails to extend we used to land on the three remaining. Crazy wing low attitude on taxi off the runway and anyway there's no (legal) way to retract a wing gear by itself.
The throttle bar was vital when flying with those ghastly JT9D-3A engines. Above FL290 it was slid into place to prevent taking off too much thrust which would lead to the self destruction of the engine usually. We descended at M.86/340 kts as I recall it. Those -3A engines were a nightmare to handle especially on the ground. We were so glad when they were modded to -7 status and actually worked.
The wing gear as speed brake on B747 Classic series was disabled decades ago. I used it a few times - as noisy as hell. In the event one wing gear fails to extend we used to land on the three remaining. Crazy wing low attitude on taxi off the runway and anyway there's no (legal) way to retract a wing gear by itself.
The throttle bar was vital when flying with those ghastly JT9D-3A engines. Above FL290 it was slid into place to prevent taking off too much thrust which would lead to the self destruction of the engine usually. We descended at M.86/340 kts as I recall it. Those -3A engines were a nightmare to handle especially on the ground. We were so glad when they were modded to -7 status and actually worked.
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From: on the ground
Last edited by nonsense; 5th December 2024 at 10:10. Reason: Links mutilated
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From: Asia
Ah, the early 747 landing gear. Anyone remember the MLG Load Evener system. A good idea that did not pan out in practice. Used to get worried when one showed up with a WLG/BLG pair adding up to the bare minimum (7.5inches??) wondering how the hell you were supposed service it a line station.
The throttle bar was only one of many quirks of the dreadful early JT9D. I did not mind the early entry into service issues the airframe had but the JT9D. destroyed whatever faith I had in P & W.
The Convair 880 (and presumably the 990) had a separate MLG Speedbrake Lever just behind the spoiler/speedbrake lever that enabled dropping the mains only for use as speedbrakes. Don't know if it was used much. I suspect the nose gear was not used due to the aft door being unable to handle the air loads.
The throttle bar was only one of many quirks of the dreadful early JT9D. I did not mind the early entry into service issues the airframe had but the JT9D. destroyed whatever faith I had in P & W.
The Convair 880 (and presumably the 990) had a separate MLG Speedbrake Lever just behind the spoiler/speedbrake lever that enabled dropping the mains only for use as speedbrakes. Don't know if it was used much. I suspect the nose gear was not used due to the aft door being unable to handle the air loads.
