Hello everyone!

I've noticed some problem with the thrust levers in my NGX. When I start descend in VNAV mode, thrust levers don't come to idle and stay a little above idle position. When I press F1 key, levers come to idle for a while and then back to previous position. As a result, the aircraft accelerate too much, and doesn't maintain programmed IAS speed for descend. The problem dissapear somewhere below FL300 (I don't remember exactly). The most strange is that even I turn off the autothrottle or change MCP mode to vertical speed, the problem doesn't dissapear and I suspect there is something wrong with my NGX or FSX, but I'd like you to make me sure before I start reinstalling software.
Thank you very much for your replies.

Sounds about normal as far as the throttle.. Should hold the FMC mach speed

until around FL300 or so, where it will merge with the FMC IAS speed.

The merge point will vary some to the speeds, etc.

So it would be normal for the IAS to be low until you descend to that point.

But from your description, I'm not sure if this is what you are seeing.

I very much doubt there is anything wrong with the NGX install.

Would probably need more info to really tell what's going on. Other things can

cause throttle issues besides the NGX itself.

Maybe it's the simulated flight idle. Or you throttle hardware override settings.

 

What N1 and N2 values are you seeing?

NM5K, in my opinion, everything would be ok, if the throttle come to idle in the moment of speed merging (as you said), but it doesn't. During descend, in the moment of speed merging, I am trying to force throttle levers to idle by disconnecting the autothrottle and pressing F1 key... then, after few seconds, throttle is going back to no-idle position. What is managing the throttle when the autothrotle is off? Is it normal? I don't think so..

 

Spin737, about 40-45% for both engines.

As far as I remember that's typical "behaviour" of jet engines: that "idle" thrust increases with airspeed and altitude ...

olli4740, I mean you are talking about N1 values, but thrust levers physically should be on idle position, and they aren't.

Guess it's 'bout time for those precision manuals ...

Ok, thanks.

 

 

about 40-45% for both engines.

40% N1 is about normal at cruise.

 

There are lots of threads on this issue. Do some searching.

This is perfectly normal. Flight idle can be upto 40% and even higher with engine anti ice on. The fact that your plane doesn't keep to its commanded speed is simply because it can't. Your probably telling it to descend on the VNAV path and therefor, with idle thrust yo are picking up speed. Again this is perfectly normal behaviour. You can use the spoilers to bring the speed back down

In the 737-700/800, the minimum N1 value at flight idle is around 32%. this value can vary considerably based on bleed configurations, atmospheric pressure, etc. Its higher than it is on the ground after eng start (around 22%) to in part, guard against flameout in heavy precip. Unless on a very gradual descent, its routine to use the flight spoilers to slow down the aircraft. You should see a "drag needed" message on the FMC if its not able to maintain your selected speed based on your VNav descent path.. 40 % N1 is not unusual especially if fully configured for landing gear/flaps etc.

olli4740, I mean you are talking about N1 values, but thrust levers physically should be on idle position, and they aren't.

 

 

Not sure about your assumption of physical lever position:

 

I searched those precision manuals and couldn't find a single hint to a throttle lever position different from the corresponding thrust setting. So, with "flight idle" higher than "ground idle", the levers will come back to their higher position automatically. Can't find anything that contradicts, anyway.

I think this is just how the sim had to mimic real life within the limitation of FSX. In the real jet, the levers are all the way back at idle and can give you varying N1/N2%, based on conditions.

 

The FSX can't do that, so NGX actually moves the TLs to an appropriate "idle" position.

 

That's my take, anyway.

Normal, it's a workaround for fsx jet engine model

This should not cause overspeed on every descent, however, when in VNAV.