My engines won't make full power!

[Graeme_77]

The Challenger 650 does not have FADEC, but there are engine controls and mechanical systems in place that affect how your lever position controls the engine. 

The most common issue seen reported with the simulation is the engines are not making "full power", or rather not achieving the rating on the N1 EICAS display. The reason for this is the engine has an N2 limit which varies based on total air temperature, which depends on aircraft speed and temperature. The TAT is shown on the PFD left side datablock, 

Don't climb at too low an indicated airspeed or mach, and keep an eye on the TAT.

This chart shows what's going on, and will also included in the Operations Reference Document when possible. Keep i mind the chart shows Corrected N2, but gives you an idea of what is actually going on. 

Edited January 22, 2022 by Graeme_77

[Melli_]

Thank you for this ^^ That explanes why my Plane wouldn't climb at first and then fall out of the sky, stalling and not excellerating, even though im doing -3000fpm ._.

[xplana]

@Graeme_77 in real world, is there something like a FLEX effect if the temperature is set to a lower value and if yes, any idea if this is being used/common? Talking about the takeoff. 

Edited January 11, 2022 by xplana

[Graeme_77]

Flex is a customer option on the 650, but an option that is very rarely installed. The reason is it actually shortens engine overhaul intervals due to some assumptions that have to be made - if flex is used the engines have to be treated as if APR was used, which is not the case on a normal takeoff with APR armed.

So flex shortens the overhaul life, increases fuel burn and reduces performance - hence not a desirable option. Maybe the only use is where an an airport has extreme noise limitations. It's not simulated on the Hot Start Challenger 650

[EGT]

On 1/11/2022 at 3:48 PM, Graeme_77 said:

So flex shortens the overhaul life, increases fuel burn and reduces performance.

 ...everything FLEX is supposed to avoid!

[Rodeo]

On 1/11/2022 at 4:48 PM, Graeme_77 said:

Maybe the only use is where an an airport has extreme noise limitations.

Would manually entering a custom N1 target via the CDU also work in this case?

[Norgan30]

Would this explain why I seem to have no trouble climbing to my cruise alt but once I get there the engines can't seem to hold it and the AoA becomes extreme and eventually I stall out? I also noticed the AP starts to go wild with the Nose Up trim as show in the picture. Does this just mean I am cruising at a too high of an ALT for the conditions for the 650?

[Rodeo]

On 1/10/2022 at 7:07 PM, Graeme_77 said:

Don't climb too slow, and keep an eye on the TAT.

Not had any engine limiting issue yet, but this is somewhat ambiguous (IMO); to avoid running into this situation, we:

• shouldn't climb at slow speeds (i.e. using a lower climb rate if necessary to ensure we have enough airspeed)
• shouldn't climb at slow rates     (i.e. using a lower airspeed if necessary to ensure we have enough climb rate)

Regards,

Tim

[Graeme_77]

Yes, you are right it's ambiguous. Speed is what I meant - "low and high" for VS rates. "fast and slow" for speeds.  The engine limits are often reached when climbing with too low an airspeed.