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Guest Ian_Riddell

Interesting Training Scenario

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Guest Ian_Riddell

Found this posting on the PPRuNe websitehttp://www.pprune.org/forums/showthread.ph...&threadid=57519It applies to the 757, but it would be interesting to know how the 767 guys would handle this.Would Flap 20 give you better ground clearance on touchdown, thus giving you more margin for error in roll control? Or would your engine hit first anyway?When you slow down, however, eventually you're going to tip over and your engine/flaps are going to hit terra firma. This raises the question... how do you slow down. If you use the brakes on one side, you're going to slew off the runway anyway (or will the rudder and nose wheel steering compensate up to a point?)Cheers.Ian.P.S. I guess this answers the question, "When do you use that Flap 20 selection on your FMC Approach Ref page?" :-)

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I think if you choose flaps 30 in that situation, you are also choosing to become a Test Pilot. As pointed out already, there is no data for proper speeds for no slats/flaps 30 and neither do I know whether there are any adverse handling effects when slowed to a VRef30 speed sans slats. I would generally choose not to have to handle both an abnormal QRH situation and explore new parts of the flight envelope at the same time.I've yet to have to land a plane with one main gear missing, but from what I've seen of others who have, it seems as though the scraping can be put off for quite awhile in the landing roll. Whether you touched down at Ref30 or Ref20 speeds, the wing can be held up long enough so that contact is made at the same low speed where the ailerons lose effectiveness.So to me, the potential benefits of Ref30 does not outweigh the additional risks for flying in an untested and unapproved portion of the flight envelope. I would stick with Ref20 approach since I would try to keep the flying as "known" as possible.

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Guest HPSOV

I'd stick with flaps 20 unless there was some overriding consideration that made a slower speed with flaps 30 a better option (very short runway would be one).I think to a degree you've already become a test pilot in this situation, you just have to do your best on the day!

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Guest Ian_Riddell

A remarkable analysis... Thanks for pointing it out, H.What I found particularly interesting was the brake anti-skid hydroplane protection circuit inhibiting the use of all 8 brakes for 16 seconds (!) on this particular aircraft type. It would be interesting to know how the 767's brakes would react under these circumstances. The 767's big brother, the 747-400, for example, appears to treat each bogey (group of four wheels) separately, so braking would probably be available much sooner. However, further reading required for both aircraft, methinks.Also, I hadn't thought of how the aircraft would pivot about the good gear on touchdown, skewing the aircraft initially to the side opposite to the faulty gear.Hats off to the crew who kept their composure and came up with modified procedures to deal with a very "non-normal" situation :-) Cheers.Ian.

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