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yimi

Uncommanded thrust increase during engine start

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I'm having problems with the thrust increasing on it's own after I start the engines. I use the Saitek Pro Flight yoke without the throttle controls. Meaning I use F1, F2, F3, and F4 to control the thrust. Before I start the engines I press F1 to verify that the thrust levers are at full idle. I have the GPU and Air Start units hooked up to the aircraft while performing the engine start. Here is what I do to start the engines.

 

1) Left click Start switch to the Start position

2) Right Fuel Control switch to Run

3) Wait for Engine #2 to stabilize

4) Repeat for engine #1

 

Now this is where the engines start spooling up on their own. For about 30-40 seconds after both engines have stabilized which is now at N1 21.7% everything is where it should be at. Then without warning the both engines spool up to ~54.7% N1 and I have to press F1 to make it go back down to idle. 

 

Anyone know why it does this? I have submitted a ticket on the PMDG website but they couldn't help me. I'm hoping somebody has some insight on this. 

 

-Thanks in advance :-) 

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  • Have you double-checked button assignments for your yoke in FSX? (any assignments for increase/decrease thrust?)
  • Any assignments in FSUIPC?
  • Any unintentional button push, maybe? Maybe a physical/electrical problem; have you checked your yoke buttons working properly from the Windows control panel (game controllers)
  • Is there a "ghost axis" still assigned to the throttles in either FSX or FSUIPC?

 

What happens after 30 - 40 sec if you do NOT start the other engine? Does the same happen to a single engine?

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I'm having problems with the thrust increasing on it's own after I start the engines. I use the Saitek Pro Flight yoke without the throttle controls. Meaning I use F1, F2, F3, and F4 to control the thrust. Before I start the engines I press F1 to verify that the thrust levers are at full idle. I have the GPU and Air Start units hooked up to the aircraft while performing the engine start. Here is what I do to start the engines.

 

1) Left click Start switch to the Start position

2) Right Fuel Control switch to Run

3) Wait for Engine #2 to stabilize

4) Repeat for engine #1

 

Now this is where the engines start spooling up on their own. For about 30-40 seconds after both engines have stabilized which is now at N1 21.7% everything is where it should be at. Then without warning the both engines spool up to ~54.7% N1 and I have to press F1 to make it go back down to idle.

 

Anyone know why it does this? I have submitted a ticket on the PMDG website but they couldn't help me. I'm hoping somebody has some insight on this.

 

-Thanks in advance :-)

It also happened to me for one time.I thought it was a problem about autothrottle disconnection fail because it happened me after pushback to return Rome.It was my second leg in flight.

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  • Have you double-checked button assignments for your yoke in FSX? (any assignments for increase/decrease thrust?)
  • Any assignments in FSUIPC?
  • Any unintentional button push, maybe? Maybe a physical/electrical problem; have you checked your yoke buttons working properly from the Windows control panel (game controllers)
  • Is there a "ghost axis" still assigned to the throttles in either FSX or FSUIPC?

 

What happens after 30 - 40 sec if you do NOT start the other engine? Does the same happen to a single engine?

 

 

If I just start one engine for example engine #2 and NOT start engine #1, the thrust increase does NOT happen. Engine #2 just stays at idle thrust. I've let it do that for a solid 10 minutes and the thrust hasn't increased on its own. So this means that the thrust only increases when both engines have been started and sat at idle for 30-40 second. Then that is when thrust increases to 54.7% N1. 

 

The only key I have assigned to my yoke is the Rudder pedals. I do not have anything assigned to it that has anything to do with increasing/decreasing thrust. 

 

The only settings I use FSUIPC for is the Wind Smoothing option. I have not touched any of the other tabs in FSUIPC to assign any joystick assignments. 

 

However I would like to point out that when I went to the Settings - Controls section in FSX and clicked on the Control Axes tab and scrolled down to the bottom I noticed that the Throttle Axis assignment was assigned to a "Z Axis". So I highlighted Throttle Axis and clicked on Delete Joystick Assignment and it went away. 

 

So my question is what is this "Z Axis" that I saw assigned to the throttles? I also noticed the Aileron Axis was assigned to the X Axis and Elevator Axis assigned to the Y Axis. I know what those are but not sure about the Z Axis. Would anyone care to explain to me? Because removing the Z Axis still hasn't solved the problem for me. 

 

The thrust still increases to 54.7% N1 with absolutely no input from me whatsoever. I am not pushing any buttons unintentionally on my yoke. Same thing with my keyboard. 

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'Z' is just another name for another hardware axis or lever: For example, my CH yoke has three levers mounted on the top, and certainly one of them is named the 'Z' axis/lever.

 

Not sure, where the 'Z' assignment in your controller settings comes from and I'm puzzled by your findings. Only thing I'm rather sure of is that it's none of those FCOM things ...

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'Z' is just another name for another hardware axis or lever: For example, my CH yoke has three levers mounted on the top, and certainly one of them is named the 'Z' axis/lever.

 

Not sure, where the 'Z' assignment in your controller settings comes from and I'm puzzled by your findings. Only thing I'm rather sure of is that it's none of those FCOM things ...

 

So what do you suggest I do? I've already submitted a ticket to PMDG and they don't know how to fix this problem. I'm out of options at this point...*sigh*

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Well, at this point i suggest to uninstall and reinstall the product, and check if the problem persists.

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What happens if you totally disconnect your hardware from the sim? If it doesn't happen then I have to think somehow the hardware *is* commanding the thrust.

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What happens if you totally disconnect your hardware from the sim? If it doesn't happen then I have to think somehow the hardware *is* commanding the thrust.

 

Ryan,

 

I have tried your suggestion by disconnecting my yoke from FSX. I loaded the 777 with the engines running, shut down the engines, and started them back up. There is NO thrust increase as of right now. It has been 5 minutes and nothing has happened. N1 remains at idle 21.7%. You were right, somehow my yoke *is* commanding the thrust. Very strange..because as I have said in the previous posts, I do not have anything linked to the yoke to increase/decrease thrust. 

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Do you have your yoke calibrated through FSX, Saitek software or FSUIPC?

 

Suggest that you calibrate through FSUIPC and see if that makes a difference

 

Rob

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