25% maximum assumed temperatue derat, what does that mean?

[JimmyPals]

25% maximum assumed temperature derate, what does that mean?

Hi all,

I know what assumed temperature is.
I also know that there is a maximum of 25% that you can derate in this way. More is not allowed.
But what does the 25% mean? 25% of what?

For example, how much thrust will a 27k engine give when 25% assumed temperature has been derated?


Regards,
Jimmy

[safelife]

Thrust. You may reduce the full-rated (flat rating) thrust by no more than 25%.
Often climb thrust will be just about that value.

[safelife]

Or, to do the math for you, 20250 lbs.