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.
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.
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!
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)
Last edited by ExSp33db1rd; 30th Apr 2012 at 09:31.
The drag, at high speeds, on the nose gear assembly (with the gravel deflector) is such that the nose gear will not extend but the main gear will.
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.