737NG Series autopilot problems

[Guest barkyh]

hi all,i am flying the pmdg 900 for some time now without any problems.but since a few days, the autopilot does not work anymore in neither of the aircrafts.But only with PDMG aircrafts - other add-on planes just work fine.Here's the problem:i set the fmc with all data - after t/o switch on the a/p after climbing thru' 2000'the airplane starts to shake extremly left to right and vice versa before it startsto turn to set heading. second, the autopilot for vertical movements reacts as follows:set the ALT on the MCP to FL200 and v/s 2000 fpm spd is set to 280. the ac reachesthe altitude but instead of leveling out it shoots thru' the set altitude and increasesthe v/s to 6000 fpm and even more. the speed decreases dramatically. then the acstarts to descend and again shoots thru' FL200 and the speed increases then it shootsway over fl200 again, descends etc. when looking at the jet trails it looks like a sinus curve.the happens even when programming the fmc with VNAV and LNAV.by the way, the weather was the default 'beautiful weather with clear skies and no winds'.nothing was changed, only that i installed the saitek ProFlight Yoke and rudder controls.Any help on this issue would be very great - since right now i can't fly these aircrafts!

[downscc 1,327]

First, please sign you name to posts in this forum... just one of the few rules.You problem description puzzles me because you mention both using VNAV/LNAV and speed 280 V/S 2000... so I am not sure what mode of automation you are using.May we please have a screen shot of her misbehaving to better understand the situation.

[michal 44]

I suspect it is user error in handling/understanding autopilot's modes. I would grab Timothy Metzinger's tutorial and go through it step by step, it does great job in teaching you about the 737NG flying.