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avgaskoolaid

Autopilot Oscilating

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Sorry if this has been discussed before... While I was flying from Krakow to Amsterdam today in my Dreamwings EMB-170, I experienced quite an annoying problem. When i leveled off at FL300, the autopilot was 'chasing' the VS indicator, and the plane kept pitching up and then down. I climbed up to FL350 to see if that would solve the problem, but it didn't. i also tried descending back down to FL300, but that didn't help either. I have flown this aircraft before without experiencing this problem, and I have no idea what might be causing it. Does anyone have any ideas? Thanks. hamoody

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Guest jahman

If this happened only once I would just ignore the problem, could be a fluke. Sometomes when I reload a flight in my PMDG 744 I also get wild excursions in VS that while not divergent, don't damp either. So I switch the AP off and dampen the oscillations myself (akthough I could switch the AP Mode from Altitude Hold to VS and then use the VS whell to dampen the ascillations. Note than an AP malfuction could do this to you in the RW as well, so it's good to develop AP-taming skills! Cheers, - jahman.

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Check what is assigned to elevator trim (up) and (down) in your sim settings. Make sure they aren't set to the wheel.


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If this happens consistently I usually make a modification to the .air fileusing AirEd. First back up the .air file of course.Open it with AirEd and go to record 1101 Primary AerodynamicsExpand it.Go down to entry Cm_dt Pitch Moment - Trim It will look something like -2.550000Increase it by a small amount to say -2.800000 and see if that solves it.If not increase it a little more. You want the smallest change that solvesthe problem. There are a lot of entries in this section that have similar names, so doublecheck the entry you are changing. Jim

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