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MadBilo

738 NG 40% N1

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Hello, I was wondering something,

Before we give TOGA we usually give 40% N1 to see if stable and as far as I recall once N1 has reached stable 40% the EGT decreases which makes it "stable" then we give TOGA.

Can anyone confirm this? 

 


I looked at many videos online and I see the EGT decreasing before they give TOGA, in the simulator my EGT is always increasing and staying the same, no decreasing.


Thank you,

Necmi Osman. 

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The EGT decrease is not simulated in the NGX, do not know why. 

Cheers!

  • Upvote 1

Ron Hamilton

 

"95% is half the truth, but most of it is lies, but if you read half of what is written, you'll be okay." __ Honey Boo Boo's Mom

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25 minutes ago, fakeflyer737 said:

The EGT decrease is not simulated in the NGX, do not know why. 

Cheers!

Roger! I wonder if they will implement it!

Necmi Osman

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Hi,

EGT park up and then decreases DURING START before engine stablizes at ground idle (20%n1, 60%n2% ff 300 kg/h) that is corrected simulated. From idle it increases proportionally to n2% . (Reflecting the difference between the turbine engine temp minus the enthalpic work of the turbine). At the start it peaks up after ignition 'cause while fuel flow is almost fixed airflow has a proportionality with compressor speeds (fuel/air ratio).

Best

Andrea Buono

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Basically you need more umph to accelerate the engine. You move the thrust lever to set the bugs at 40% and the engine will fuel to accelerate to the bug, I must admit I never really notice it much. I just smoothly raise power to 40% and once they both reach it, I press TOGA and look out the front window... 


Mark Harris.

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Hi,

I've been just last Saturday in a fixed base trainer simulator of b738 (I go there each two months for a 2hours training) and I've already spent about 50 hours in those simulators  but I've never seen an EGT decreasing when accelerating from 20% to 40% n1%...(the only engine having a decreasing from idle to let's say 40-50 n1, I can't well remember, is the IAE-V2500 I've seen that by looking at real A320 airplane cockpit video by youtube..)...

Ciao

Andrea Buono 

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The primary reason for the 40% then TOGA procedure is to insure the engines come up to takeoff power together.  Often in the airplane when you push the levers to the 40% point one engine will reach 40% before the other.  You wait until both engines are stable at 40, then press TOGA.  Going straight to TOGA without the intermediate step can result in directional control problems if one engine spools up quicker than the other.

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