trim problems

[niokilt 0]

hi,

 

i have read some topics about trims problems but i didn't find one relating mine.

i have just started a flight with the 777, everithing is fine and configured as it should, espacially the trim. couple of seconds after rotation, the aircraft pithes down, alone. I mean without any controls input...., ok, i look down the trim is moving down itself without command.auto trim, yes ok but not possible that way....

Ok i stabilize the aircraft, perfect stabilzed cruise flight at  low altitude, suddenly its starts again, pitches down or up (it goes on a way or the other) without any input from me. It sounds like a bug, the aircraft is impssible to fly...

 

please help!

[jimmy64 43]

Looking for an answer to this too.

[Budbud 227]

hi,

 

i have read some topics about trims problems but i didn't find one relating mine.

i have just started a flight with the 777, everithing is fine and configured as it should, espacially the trim. couple of seconds after rotation, the aircraft pithes down, alone. I mean without any controls input...., ok, i look down the trim is moving down itself without command.auto trim, yes ok but not possible that way....

Ok i stabilize the aircraft, perfect stabilzed cruise flight at  low altitude, suddenly its starts again, pitches down or up (it goes on a way or the other) without any input from me. It sounds like a bug, the aircraft is impssible to fly...

 

please help!

 

Hi,

 

Full names on that forum please, it is a mandatory rule.

 

Then my first thought would be that it may be a hardware related problem (spikes or double assigned controls).

Have you checked that you don't have some buttons assigned to the trim? 

Have you also tried to disconnect your hardware devices in flight? FSX has that bad habit to assign controls to the hardware by itself when they are plugged for the first time and it is easy to miss it.

[niokilt 0]

Hi thanks for the comment,

 

No I didn't try to remove the hardware during the flight, the thing is: it doesn't do that with every of my add-ons... otherwise, it is true that normal buttons of my yoke are assigned to the trim and it does control the trim of the aircraft,( which i can see moving on the 777 yoke) but that sounds normal doesnt it?

[Budbud 227]

You may try to disconnect it anyway just to be sure.

 

Also what panel state do you use?

[downscc 1,327]

Nick, as Romain has pointed out your problem with uncommanded trim changes when not in an autopilot mode is not a bug in the product.

 

The PMDG product gets trim commands from the simulator platform (FSX/P3D), which is why Romain is pointing to the areas he has for you.  In simple terms, there is a keycommand such as Num 7 or Num 1 which the platform sees as a trim command and passes it along to the aircraft.  Make sure that the use of either of those two keycommands is only assigned once or as you want. Look for something that is sneeking those commands past you while your not pressing the button.

 

The usual culprit is how FSUIPC is set up, which can do some pretty unpredictable things.

[niokilt 0]

ok I understand, I am going to check that and I will comme back to you! thanks

[niokilt 0]

ok my feedback. In think that you were right about the hardware. I use a joystick for the tiller. there were indeed some other assignements to the trim like you said and removed everithing so that the only connection is on the yoke. So of course I noticed the change, but strangely, it stills behaves sometimes like it is working on its own, especially when reaching altitudes or capturing the glide... honestly i guess it is a lack of knowledge on the FBW system. I need to read deeply the manual and watch some you tube videos. because obviously, it is a different aircraft to fly.. and I don't find it confortable as when I fly the NGX. I found that on the fms options you can set on the speed tab the FBW bug and I noticed that when putting this bug over the speed you re flying it sounds  easier.. but i don't know why.. so I need to know ore about this.

[skelsey 765]

Honestly -- don't over-think the trim too much.

 

The 777 trims for speed. But so, basically, does a Cessna or indeed the 737 -- the only difference is that the 777 does it via a computer.

 

If you're having to maintain a pull force on the yoke to maintain the flight path you want: trim nose up. If you're having to maintain a push force, trim nose down. KISS