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virtualflying

PMDG 777 Autothrottle/Toga question

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Evening everyone,

 

I didn't want to post this in PMDG forum because it wasn't a "support" question, but here's my dilemma:

 

I load my FP and everything, and go to take off, so I add about 70%, and then hit the toga button.

 

Everything is fine, until about 80 knots, when EVERY TIME I take off, the throttles just die, and go back down to idle, and I have to manually push the throttles forward again.

 

I also have where, I will be descending via VNAV and LNAV, and the throttles will just go full TOGA, and make me overspeed, and I have to manually bring them back down.

 

Any help? It's very annoying

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It sounds like an issue where the manual position of your throttles is over-riding the autothrottle position. Are you following through and pushing your throttles up when pressing TOGA and the thrust is advancing? Also what have you set in the FMC menu for throttles-manual override? Try it in NEVER or HOLD MODE ONLY. 

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Everything is fine, until about 80 knots, when EVERY TIME I take off, the throttles just die, and go back down to idle, and I have to manually push the throttles forward again.

 

I also have where, I will be descending via VNAV and LNAV, and the throttles will just go full TOGA, and make me overspeed, and I have to manually bring them back down.

 

Most likely your throttle hardware is sending spikes/commands that you are unaware of.  In both situations the Autothrottle (A/T) is most likely in HOLD mode, which allows movement of the throttle levers to adjust thrust.  

On takeoff, the Autothrottle goes into HOLD mode at 80 knots.  This allows manual adjustment of thrust; if your throttle hardware is set to a minimum position and you touch it accidentally or it sends a spike, thrust will drop. 

 

In VNAV descents the Autothrottle also often goes into HOLD mode.  Again, depending on your hardware throttle's position, you might send a full thrust or other command that you are unaware of.

 

For both situations, check what thrust mode the A/T is in on the FMA (upper right of PFD for Thrust mode).  See if it is in HOLD mode.

 

There is also an option to display the hardware throttle position on the N1 EICAS indications.  That should help you troubleshoot. 

 

Mike

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This is exactly the kind of question you can ask in the PMDG customer forum. Other users are there to help out, including Mike.

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It sounds like an issue where the manual position of your throttles is over-riding the autothrottle position. Are you following through and pushing your throttles up when pressing TOGA and the thrust is advancing? Also what have you set in the FMC menu for throttles-manual override? Try it in NEVER or HOLD MODE ONLY. 

 

I normally move my hardware about 70%, then hit the toga button (I keep my hardware at 70%), and in the FMC, I don't put the thrust in there. I'm still a big noob to the 777, so I don't know what that does/how to calculate that. :P

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Moved to PMDG forum as this *is* a PMDG support question--OP, you'll need to put your name to any future posts in the thread.

 

Regards

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I'm still a big noob to the 777

If you have not flown Tutorial 1, you should. The correct take off procedure and descent is covered. The Introduction is a must read also if you don't want to be a big noob.

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I normally move my hardware about 70%, then hit the toga button (I keep my hardware at 70%), and in the FMC, I don't put the thrust in there. I'm still a big noob to the 777, so I don't know what that does/how to calculate that. :P

 

i heartily agree with Michael C.'s suggestion that you fly the tutorial and read the intro manual carefully.

 

Also, I mis-spoke in my earlier entry.  Thrust mode is shown on upper LEFT side of PFD.  Pay attention to what thrust mode you are in when the thrust reduces or increases unexpectedly.  Again, I am guessing that your issues are arising from accidental throttle hardware inputs in HOLD mode, both on takeoff and during VNAV descents.  Search FCOM2 for "Hold mode" -- you will see that the autothrottle stops controlling the throttle levers in that mode, leaving them open  to any deliberate or accidental input from your throttle hardware.  Also read up on the options for how you set your throttle hardware to override the autothrottle commands. 

 

As Bob S. said, PMDG wants you to sign your full name in its forums.

 

Mike

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