Trim adjusting itself

[CBStu]

To skip all the quick moves needed in a traditional pattern trap, to try to diagnose, I approach at about 3000ft at 10 miles out. Chop to idle and drop gear and hook just under 250. At just under 190 go to full flaps and adjusting trim to get on AOA. So I get centered in the E bracket and fly the ICLS cross. I keep needing to add more up trim. I get the screen up to watch the trim # and as I drop lower in the E I see trim dropping, 16deg,15, 13, 12. When I do a quick hit on the trim button, I see the # climb along w/ the VV in the E. But this is constant and has been for at least a month. Used to be each adjustment had a huge wild effect, almost uncontrollable. The last couple of days it has calmed down but the constant trim loss is still there. Anyone else having this problem? Any ideas for diagnosis technique?

[rob10]

That seems like a binding problem.  An axis sending erratic input?  I'd start with assigning both up/down to something other than current.  Actually maybe just assigning them to keypress only.  Or copy your inputs folder and set up only basic controls and see if you're still seeing it.

[Razor18]

I would also check my controls, as updates use to randomly mess up previously flawless keybinds by duplicating command to another keys/axes. SO go into your controls list, and try to move your trim button up down, see if the highlight jumps to the line "Trimm", dna check (and delet if so) any other input key or axis in the same line. I had sometimes my right throttle assigned to the rudder after an update, or trimm hat switch reassigned to camera view motion an other oddities...

[Habu_69]

Theory: fuel consumption reduces aircraft mass and shifts CG.

[Razor18]

2 minutes ago, Habu_69 said:

Theory: fuel consumption reduces aircraft mass and shifts CG.

That would show along a much longer period of time. And he's not talking about the need to change it once every half an hour or so, he is talking about uncommanded change continuing after a trim hat nudge in up or down direction.

[CBStu]

I will check through bindings later today and let you know what I find. Thanks.

[maxTRX]

Sounds like it could be related to transition to PA mode with AP engaged. Were you using any AP mode and didn't disengage it before dropping flaps? 

It thought this bug was fixed already... if that's what the problem is in your case.

[CBStu]

PA mode??? I don't know what that means but I am pretty sure I had used AP in BALT mode on the flight back to the carrier. I tend to use that a lot and it's definitely possible that I didn't properly shut it off. BTW when in BALT it kind of stiffens the feeling in the stick and at a certain point, say in making a turn and I go too tight, it feels like the stick pops loose and AP is no longer working. Would that cause a problem if I never properly shut off AP?

[Tholozor]

PA = Powered Approach (i.e. landing configuration).

Edited November 27, 2021 by Tholozor

[rob10]

2 hours ago, CBStu said:

PA mode??? I don't know what that means but I am pretty sure I had used AP in BALT mode on the flight back to the carrier. I tend to use that a lot and it's definitely possible that I didn't properly shut it off. BTW when in BALT it kind of stiffens the feeling in the stick and at a certain point, say in making a turn and I go too tight, it feels like the stick pops loose and AP is no longer working. Would that cause a problem if I never properly shut off AP?

Could be your problem.  The stiffness followed by ".... the stick pops loose and AP is no longer working." would actually suggest you still had AP still working.  There is a  mode (can't remember exactly what it's called ATM ) is basically AP acting to dampen your inputs (rather than holding a specific heading, altitude etc).  Having any part of the AP on, this stick will seem "stiff" until you move it far enough to cause the AP to disengage, then it will "pop" free.  If you select the AP button under the UFC and then the ON/OFF button rather than one of the AP modes on the UFC, you'll end up in this mode.  Also if you just decolonize your current mode on the UFC you'll end up in the AP dampening mode.  To completely turn off AP you need use the paddle switch.

Edited November 27, 2021 by rob10

[Tholozor]

51 minutes ago, rob10 said:

There is a  mode (can't remember exactly what it's called ATM ) is basically AP acting to dampen your inputs (rather than holding a specific heading, altitude etc). 

CSS, Command Stick Steering. It's denoted by an 'A/P' advisory as opposed to dedicated A/P advisories like 'BALT' or 'RALT.'

[CBStu]

rob and Tholozor thank you. I have a button on my stick to disengage AP but I am thinking I may have been getting lazy and not using it. I often fly back to the ship in AP-BALT and just make small nudges to the stick to correct heading. But eventually I need to either descend or make a more serious turn and just do it until the stick pops loose. I will also check binding for that switch. I did check trim switch bindings and found only one set of them.

[rob10]

6 hours ago, CBStu said:

rob and Tholozor thank you. I have a button on my stick to disengage AP but I am thinking I may have been getting lazy and not using it. I often fly back to the ship in AP-BALT and just make small nudges to the stick to correct heading. But eventually I need to either descend or make a more serious turn and just do it until the stick pops loose. I will also check binding for that switch. I did check trim switch bindings and found only one set of them.

Yep, cancelling AP-BALT that way will definitely leave you in CSS which will make your controls behave differently than you'd expect.

[CBStu]

A huge thankyou to everyone who helped me out. I have done three carrier traps in 3 different missions and they all worked just fine. Doing a specific AP shut off fixed my 'trim moving on it's own' problem. Thank you all. 

[CBStu]

So all has been well since my 11/28 post until yesterday. Then the old problem occurred. But it only lasted 10-15 seconds. Why? Because I remembered this thread, thought back a bit through this flight, and realized I had used B-Alt way back at the beginning of the flight. Hit my 'shut off AP' button and bam, all was well. Thanks once more guys. 

[bumfire]

Pitch and Roll Trim doesn’t work for me at all, I’m using the F18 thrustmaster stick for my warthog base. It’s not a key binding problem as I cleared all the key binds for the trim settings and then re-added them using the hat thats meant to be used for trimming, the hat works in every other aircraft and even in the f18 if its used to bind something else.

Looks like I have got alot of reading up to do, or if its a bug, maybe somebody can let me know.