eXpress48

777 Thrust Lost during Takeoff Roll

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Hello

I own the PMDG 777 for P3D v4 for a few days and I have one little issue that I'm currently unable to solve on my own. During Takeoff Roll, when the 777 accelerates, the thrust suddenly goes back when V1 / VR is being reached.

As far as I'm aware, I've completed the MCP Prepration as followed:

- Both Flight Directors are armed
- Both AT/R are armed
- The V2 Speed is entered in IAS
- LNAV / VNAV is armed

During takeoff, I manually set about 50% of N1 and then I press the Toga Button. The N1 then goes to about 90%, based on my Temperature Setting in the FMC, and suddenly goes back to around 50% when the Plane reaches V1 /VR.

Has anyone seen something like this or if I'm making a mistake?

Thanks.

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Are you moving your physical throttle with the increase in thrust? If not, the physical throttle may override the one in the plane.

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3 hours ago, eXpress48 said:

Hello

I own the PMDG 777 for P3D v4 for a few days and I have one little issue that I'm currently unable to solve on my own. During Takeoff Roll, when the 777 accelerates, the thrust suddenly goes back when V1 / VR is being reached.

As far as I'm aware, I've completed the MCP Prepration as followed:

- Both Flight Directors are armed
- Both AT/R are armed
- The V2 Speed is entered in IAS
- LNAV / VNAV is armed

During takeoff, I manually set about 50% of N1 and then I press the Toga Button. The N1 then goes to about 90%, based on my Temperature Setting in the FMC, and suddenly goes back to around 50% when the Plane reaches V1 /VR.

Has anyone seen something like this or if I'm making a mistake?

Thanks.

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As Andre said it might be your physical thottle interfering. THe best practice is as soon as you press Toga and before HOLD in annunciated on the FMA to move your physical throttle levers all forward and leave them there until T/D. When on T/D place them back in idle

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@Olympic260 Thanks for the hint. Signature added 🙂

Thank you for the replies. This was one my first guesses that my Throttle is actually interfering. After applying 50% N1 and pressing TOGA I haven't touched the Throttle, however the Reduction still happens.

I'll try your suggestion with moving them all forward after pressing TOGA.

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When the auto-throttle goes into HOLD mode, you have full control of the thrust levers. If you left your thrust levers halfway and there was a signal spike in your thrust levers for whatever reason, that's why you lost thrust. Simple fix, really.

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Just tested this, moving the Throttle all the way forward after pressing the TOGA Button worked. No more sudden Thrust Lost 🙂

Thanks for the help.

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1 hour ago, eXpress48 said:

Just tested this, moving the Throttle all the way forward after pressing the TOGA Button worked. No more sudden Thrust Lost 🙂

Thanks for the help.

The only caution is that you want to do this before 80 kts, which is when it kicks into HOLD.  During HOLD any throttle movement will override the TOGA thrust.

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My procedure is to set throttles to 55% N1, hit TOGA and push the throttles fully forward and hold my right hand above the throttles (until V1) in case of RTO but not actually touch them. After takeoff, during climb, I'll match the throttles with the actual thrust. No problems from spiking.

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Moving the throttles fully forward is a must for the 747 and 777, but I have noticed that it does not seem to affect the 737 NGX on my PC. However, I do the same with the 737 as a matter of good practice.

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16 hours ago, Christopher Low said:

Moving the throttles fully forward is a must for the 747 and 777

I can't say I've ever moved them fully forward, as I never do that even with a manual thrust settings. I do, however, push them up as far forwards as I think would match the thrust setting I've selected.

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What you also can do is disable the override im the CDU Options AND then assign a button on your throttles via FSUIPC to send „F1“ and check „repeat when hold“. This will also move the throttles to idle and activate RTO. 

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