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Guest meyomyx

60% N1 commanded at V1/Vr - New Post/Info

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This problem occurs only after a flight reset - not with a fresh flight.When approaching V1/Vr, The THR HOLD annunication changes to MCP SPD and approx 60% N1 is commanded leading to crash unless autothrottle is selected off and full throttle applied quickly!This fault has become apparent as I am flying SIDs repetitively to check SIDSTAR file programming.It became apparent that occasionally it would not occur but, more often would - but never on a fresh flight.A previous post discussed many possibilities but none explained this. I have now discovered a critical piece of information in that CWS P is somehow engaged (uncommanded - and annunicated on the PFD in tiny yellow text) at rotation. Reading the manual, it would appear that CWS will engage if sustained control input (in this instance rotation!) is made when the AP is in CMD mode.Obviously at this point the AP is not active and CWS has not been selected.Exactly the same procedures with a "fresh" take off do not allow this to happen.It would seem as though on a reset flight, or similar, the program still thinks that the AP is in CMD mode and interprets rotation as a signal to engage CWS - which leads to the MCP SPD annunication.If you use a lot of UP trim to take off, you can avoid the control wheel pull substantially and avoid the problem !Any thoughts PDMG?Thanks in advance

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Maybe it's like you stated, somehow FS is holding some memory. If that is the case I would delete any saved flight files and make sure to always start in a powered down condition {cold & dark) or NEW flight, not reset... Best Wishes,[h4]Randy J. Smith[/h4][h3]P M D G's 747-400[/h3][h4]coming to a runway near you[/h4][/font color]Caution! Not a real pilot, but do play one on TV ;-)AMD 64 3200+ | ASUS KV8 DELUXE | GFORCE 5700 ULTRA @535/1000 | Maxtor 6Y080M0 SATA 80 GIG | 512 DDR 400 | Windows Xp Pro | Windows Xp Pro 64 |

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There are a few things I don't understand here, Nick....When did your SPD button illuminate? I'm sure you shouldn't being seeing this on takeoff. Did you push this button rather than pushing the TOGA "screw"? CWS shouldn't engage unless you select it... or you previously had your A/P engaged and moved the control column. Did you try to take off with your A/P engaged?Your V2 speed (in the MCP speed window) seems a little high.... especially for Flaps 10. How heavy were you?Curiouser and curiouser.Cheers.Ian.P.S. BTW, nice to see someone from the Isle of White... I used to go there for my holidays (when I was a young lad). :-)

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Hi IanThe SPD button illuminates when the mode changes from THR HLD to MCP SPD.V2 set is 147 which is amended to 167 by the FMC as it should.Can't take off "with the A/P engaged" - as you can see from the CWS and AP channel switches.I think you're right though in that the A/P would have been fully active when the flight is reset or restarted. CWS seems to engage with the sustained control pressure of rotation - somehow thinking that the A/P is fully active.I wonder if briefly pulling the disconnect A/P switch before take off would reset?Odd....... ah the Isle of Wight. Most people seem to have been here in their youth. Nice. Mind you there's an angry weather system (for summer) rattling through today - a whole gale outside!Cheers :-beerchug

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Hi Nick,I think you found a workaround for something that has been a problem also for me when resetting a flight after takeoff.I did what you suggested, to briefly pulling the disconnect A/P switch before takeoff, and now I don

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AhhI haven't tried it yet - it works? Oh good!! I will confirm this end.If PMDG are watching - build in an A/P reset when flight reset to the next upgrade please! Thanks

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Personally I have added that in as part of my shut down procedure. I had not experienced problems but I always flipped the disconnect because I knew that even after I shut down the A/P on final it still controled speed so I didn't want anything to happen once I kicked on the A/T on the next take off. I guess that kept me from seeing this particular problem.

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