AP is off, why is the trim moving?

[BabtridgeMcJoystick]

Hi there

Apologies if this is a common or obvious question, I have done a search on the forum and web and in the manual but my search-fu has failed me.

For some reason during flight, my trim wheel is moving by itself. I figured I must have the autopilot on, but I am learning how to use it and can't tell if its fully 'disarmed' or not. All it shows is altitude info and nothing else, if that's any indication?

Anyway, on landing, the trim wheel starts moving by itself making it really tough to land. Completely switching off the avionics stack obviously works, but can someone point me in the right direction? At the moment I just purely want to hand fly as if I am a student (which I am )

Thanks!

[Lewis - A2A]

Hello,

It does sound like you have the AP on. When you turn off the AP using the master AP button you should hear some warning beeps as you turn it off. Also just to check you are fully updated please run the latest updater here; http://a2asimulations.com/forum/viewtop ... 07&t=41279

thanks,
Lewis

[Nick - A2A]

For some reason during flight, my trim wheel is moving by itself. I figured I must have the autopilot on, but I am learning how to use it and can't tell if its fully 'disarmed' or not. All it shows is altitude info and nothing else, if that's any indication?

This does sound a little odd. When the autopilot is powered through the avionics bus, but not engaged, it'll show the altitude selected and nothing else which is what you seem to describe. At this point, the autopilot trim servo should be disconnected, so no automatic movement of the trim wheel.

When the autopilot is engaged (by pressing the 'AP' button for 0.25 seconds) the '[AP]' caption will be visible on the screen as well, along with an indication of whichever lateral and vertical modes are active. The latter will be either 'VS' which is the default on engagement, or 'ALT'. In other words, the trim wheel should only be moving by itself if the screen shows '[AP]' and 'VS' or 'ALT' as well as the altitude selected.

As Lewis mentions, disconnecting the autopilot (by pressing the 'AP' button or using the AP disconnect switch via the A2A input configurator) will cause a 2 second continuous aural tone. If you're not hearing this, maybe there's a controller conflict or something. Do you use any advanced hardware to control the autopilot?

Cheers,
Nick

[BabtridgeMcJoystick]

Hi guys, thanks for the responses. Yeah I am not sure whats up really. I am definitely on the most recent version, as the updater stopped and told me.

I have been flying around most of the afternoon and evening with no problems. All seemed ok until my last landing. I checked AP was off. I tried turning it on, and saw the ROL indicator. Then I turned it off and heard the 2 second beep. Nothing was showing in the window apart from altitude info, though from time to time an ALERT message appears? Anyway I was using an ILS beacon and as I was doing the roundout, sure enough the trim wheel whacked itself to full nose up and I had to fight the plane to the ground.

Its weird because I did another ILS landing and there was no problem at all. When I had the problem before, the altitude was set to 1000 feet, so I tried setting it to 0 feet, thinking that maybe it was treating 1000 as a hard deck and trying to avoid it. Thats why you can now see 0 in this pic (warning 2K resolution).

http://i.imgur.com/vEVkxac.jpg

EDIT: @ Nick M, no I haven't got any nice avionics units or anything sadly, though I am sure my wallet will get another beating sometime soon for one

[Nick - A2A]

Then I turned it off and heard the 2 second beep. Nothing was showing in the window apart from altitude info, though from time to time an ALERT message appears?

Hmm? Well, the 'ALERT' annunciation is nothing out of the ordinary anyway. The KAP 140 autopilot includes an altitude alerter function which is operational even when the autopilot's not engaged. It'll cause that 'ALERT' message to appear as described in the autopilot manual which is available here:

"ALTITUDE ALERT (ALERT) ANNUNCIATION - The ALERT annunciate is illuminated 1000 ft. prior to the selected altitude, extinguishes 200 ft. prior to the selected altitude and illuminates momentarily when the selected altitude is reached. Once the selected altitude is reached a flashing ALERT illumination signifies that the 200 ft. “safe band” has been exceeded and will remain illuminated until 1000 ft. from the selected altitude. Associated with the visual alerting is an aural alert (5 short tones) which occurs 1000 feet from the selected altitude upon approaching the altitude and 200 feet from the selected altitude on leaving the altitude."

I am definitely on the most recent version, as the updater stopped and told me.

I think the updater can be 'fooled' if you've reinstalled the software at any point. To be on the safe side, maybe try deleting the following folder and then running the updater again:

...Microsoft Flight Simulator X\A2A\Cessna172\Update_fsx

If that doesn't work, any chance you could upload some video of the problems you're seeing, or perhaps a few screenshots during the approach when the trim misbeahves? Nothing in the screenshot you linked seems amiss as far as I can see.

Cheers,
Nick

[BabtridgeMcJoystick]

Hi

I have been flying around a little tonight and re-tried the ILS approach I did last night, and despite two attempts could not get the behaviour to repeat itself. So I have followed Nick's advice and deleted that folder / reinstalled the update. I think for now it will just be a case of keeping an eye out, as the problem seems intermittent and I cannot yet figure out how to cause to to repeat.

Thanks again for your help, I will keep you updated if it happens again.