I wonder if there is a way to trim the pitch by using the manual lever by the throttle control using button commands? I find that the lever trimming is smoother but I cannot find a way to link this to the joystick buttons.

 

 

I find that the lever trimming is smoother

 

smoother than what?  Interesting. Trim input to the sim is always via a set of keycommands, even if your joystick buttons are used somewhere those buttons are converted to nose up and nose down trim commands, and it is on/off.  Maybe you can play with the repeat rate that is probably assigned to your buttons, increasing or decreasing that might get you close to what you perceive with the lever controls in the model.

smoother than what?  Interesting. Trim input to the sim is always via a set of keycommands, even if your joystick buttons are used somewhere those buttons are converted to nose up and nose down trim commands, and it is on/off.  Maybe you can play with the repeat rate that is probably assigned to your buttons, increasing or decreasing that might get you close to what you perceive with the lever controls in the model.

Well I have found that the manual lever for trimming is smoother than the buttons on the wheel, but so far the only way to use the lever is to physically click on it, not good to fly with.

Well I have found that the manual lever for trimming is smoother than the buttons on the wheel, but so far the only way to use the lever is to physically click on it, not good to fly with.

The levers are an alternate backup. I've never seen a pilot use them in preference to the yoke switches. I can't imagine why anyone would prefer them in the sim either.

The levers are an alternate backup. I've never seen a pilot use them in preference to the yoke switches. I can't imagine why anyone would prefer them in the sim either.

They make trimming be smoother, more precise.

They make trimming be smoother, more precise.

Certainly not in the real aircraft and I doubt in the sim. Same for other Boeings with these type of alternate levers. I don't notice any lack of precision with the trim switches.

Yes I have to agree with Kevin here I find conventional trimming with my yoke perfectly accurate and usable on the 777. A bit strange that you find it imprecise are you sure everything is configured correctly?

I wonder if it is a case of misunderstanding the C*U laws again. Does altn. pitch trim bypass the computers?

I wonder if it is a case of misunderstanding the C*U laws again. Does altn. pitch trim bypass the computers?

No, in normal mode the alternate pitch trim changes trim reference speed and directly moves the stab. Once you release the levers the stab is once again under the control of the FBW system. The computers are not bypassed.

 

I think it's more a misunderstanding of the function of the levers. Some people seem to think they are a replacement for a trim wheel and therefore a finer adjustment.

It took me a while to move from the trim wheel to the yoke horn after I moved from SEL to MEL chariots... there was something comforting about having a gentle touch on the wheel surface and feeling the changes as I moved something instead of pressing a button. Some aircraft had a certain charming sloppy feel to them... you know, where you have to move a lttile further then come back to get the desired effect.  Then there are those Mooney's that forsworn all things sloppy and use only solid linkages to the controls.  Every plane had a unique feel to the trim.

 

Of course, reality was single pilot IFR and anything that frees-up a hand is priceless.

The levers are an alternate backup. I've never seen a pilot use them in preference to the yoke switches.

I use them for the T/O trim setting (ranging also +/-2 units above/below FMC value) after engine start, prior to taxi. This way I now the backup is working...

 

(BTW: after setting the T/O trim with the ALTNTRIM lever I briefly use the manual rudder trim knob in both directions, check the indicator and use the reset button to test its functionality, too. After that I test elevator    EDIT: aileron trim switches and yoke indication. Last thing is checking all controls by monitoring the FCTL page. Finally contacting ground: "request taxi").

^^^^ you have to do something for all the money ^^^^ B)

Edited September 16, 201510 yr by vr-pilot

I use them for the T/O trim setting (ranging also +/-2 units above/below FMC value) after engine start, prior to taxi. This way I now the backup is working...

 

(BTW: after setting the T/O trim with the ALTNTRIM lever I briefly use the manual rudder trim knob in both directions, check the indicator and use the reset button to test its functionality, too. After that I test elevator    EDIT: aileron trim switches and yoke indication. Last thing is checking all controls by monitoring the FCTL page. Finally contacting ground: "request taxi").

^^^^ you have to do something for all the money ^^^^ B)

I didn't realise you were a tubeliner pilot Claus.

 

Anyway why wouldn't the altn trim work? It uses cables connected to the hydraulic actuators. If it doesn't work it means that either the actuators are failed or the cables are broken. Surely it's better to test the pickle switches?

But I mainly meant in flight for normal trimming.

kevinh, on 16 Sept 2015 - 11:19 PM, said:

It uses cables connected to the hydraulic actuators. If it doesn't work it means that either the actuators are failed or the cables are broken.

I thought the T7 ALTN TRM would move the horizontal stabilizer to the unit indicated on the band display (Airbus=THS) on ground AND in flight.

While on ground the trim switches on the yoke would also directly move the "THS", in flight though they would first move the stabilizer's elevator (shortterm yoke input support) followed by a computed (longterm) stabilizer position adjustment (leaving the elevator in neutral position).

 

So if the OP notices a difference in the feel of both trimming capabilities this would make sense.

 

Testing the ALTN TRM lever on ground makes also sense because you would not do so in flight. Noticing the alternative is not working while in the air would be a bit "late".

Almost the same with rudder and aileron trim: checking if band/yoke indicators correspond to the FCTL page depiction shows if trims work "on top" of the normal steering action.

 

I am just wondering if "dutch roll compensation" or THRUST ASYM COMP can be seen and felt on the yoke or rudder peddals.

I think they must be both decoupled from direct control inputs AND from manual trim settings as they both should present a stable aircraft to the crew while dynamically steering/trimming it in the background?

:blink:

FCOM 9.20.11 explains how the levers work, and how they differ from the primary trim control switches. In normal mode they move the trim reference speed. The OP should note that here the FCOM states:  "The alternate pitch trim levers should not be used with the autopilot engaged...."

 

 

"The alternate pitch trim levers should not be used with the autopilot engaged...."

That said, neither should the normal pitch trim with AP engaged!