777 trim getting funny on me

[KL-666]

Somewhere below 100.000 pounds of fuel the trim goes automatically to too much up on the ground. No matter that i set it less up, it just goes automatically back in it's desired up position again. This is wrong. Trim should stay where i put it. Specifically on the ground.

Kind regards, Vincent

[Octal450]

It's because of the FBW, it doesn't work the way it should in a 777.
You can probably disable the autotrim.

[KL-666]

I heard people having trouble to reproduce it. Maybe it is not only the fuel weight, but my whole flying routine.

Normally i start with just above 100.000 pounds of fuel. With that i can do about 3-4 flights of some 300 miles length. At each airport i shut down engines and leave the plane for some 15-30 minutes. Then startup again and taxi to the runway. Reaching the runway at the 2nd or 3rd take off i notice that trim has shifted halfway up from where i put it before taxiing. Because it happens always after a few flights, i thought (wrongly) that it may be related to fuel weight.

Kind regards, Vincent

[jwocky]

Without having a deeper look, but if the trim changes only while you taxi, this has to be either Nasal or ruleset in the FBW. Can you confirm, the trim behaves normal over the first short flight? That is the Seattle 777-200LR you normally fly? Because I noticed, it has also a ruleset problem with low throttle and switches the engines off.

[Octal450]

I don't understand why Hyde has that FBW, because it doesn't work like the 777 FBW should anyways.

But, I do know that the trim is adjusted by the FBW sometimes, and prehaps Hyde never disables it when the gears touch, so eventually, it moves.

[Hyde]

I tried with short leg flight from KATL - KNAB - KATL. But could not reproduce.
I will try longer flight.

[KL-666]

A while ago i did cleanup my installation a bit. Throwing out all sorts of "packs" i had installed over the years: davepack, jpack, and probably some other packs. It was after that, that the problem started to manifest itself. I know this is not proof that it is related, but maybe by reading this, someone suddenly remembers some sort of relation between the 777 and some pack.

@Jwocky
The first flight is never a problem. The second maybe. The third goes pretty surely wrong. Yes, it is the Seattle 777-200LR i normally fly of course

Kind regards, Vincent