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Old 1st May 2019, 17:06
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Hot 'n' High
 
Join Date: Dec 2001
Location: Here 'n' there!
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Edit - Gums (and also Bill Fly) - just seen your Post 4706 when I Posted - but as I've written this forgive me for Posting anyway. Exactly! You and I are together I think on this! (If I may be so bold as to assume that?)

Originally Posted by AAKEE
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There is a pitch up moment from the engine nacell’s at high alfa but it is allways less than the pitch down coming from the CG being forward of the centre of pressure center. The nacelles pitch up moment ease the elevator work to pitch up /decrease speed, making the stick force gradient to low.
Never flown (or fixed) Boeings but, given the above which is what I think we all agree is the issue – not enough stick force at higher AoA to meet Certification due to the pitch-up moment generated by the donks homes - then surely this Thread (B737 Feel And Centering Unit) describes where the solution should have been implemented to “reprofile” Elevator Feel but for Speed and AoA rather than just for Speed – in other words, add in a bit more "aft" stick Q-resistance at high AoA.

While, ideally using a dual AoA system, if Boeing insisted on just one AoA feed, all you would have is a slightly erroneous “feel profile” at higher AoAs with a U/S AoA system (auto cured when the AoA system is fixed). This would seem far more manageable (tho it would be out of Certification limits in purist terms on AoA fail) than the MCAS erroneously trimming AND which materially affects the flightpath (and I’m deffo going to avoid any discussions on whether or not that was handleable by an “average crew” - whatever one of those is – but we do have 2 jets down with awful consequences for 100’s of people so the complete system (incl aircrew and bits and software) fell over twice).

Is that assessment correct and did MCAS seem to provide Boeing with a simpler/cheaper solution to “emulate” a change in Q rather than make changes to the Elevator Feel Computer (EFC) in it’s role as described by IFixPlanes? I can’t really recall this discussion of the EFC anywhere. Or, since that Thread was wayyy back in 2010, does the EFC no longer exist – but since Q-feel has been around for ever really - something still does that job surely. Boeing seems to be trying to keep the aircraft away from high AoA so that we don't get uncertifiable Q issues rather than sorting Q so it's certified at all AoAs. I can’t recall where the schematics appear in this thread re an EFC but just a thought … and happy to crawl back into my box if talking utter tosh! Won’t be the first time for me!

Originally Posted by AAKEE
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Gums, you have my respect for many excellent posts and a very good carreer! Thumbs up :-)
And “Here, here!” - always good to see Gums chipping in for the reasons above!

Last edited by Hot 'n' High; 1st May 2019 at 17:25.
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