EEC ALT Mode weight adjustment logic

[Manicured garden]

Hello all,
I've been wondering what is the logic behind performance limited weight adjustment for EEC ALT Mode for B737 aircrafts?
Related with this adjustment; also increase V1 and VR speeds as well.

Can anyone explain it for me? I couldn't find the reason of it.
Thanks in advance to all.

[Capt Pit Bull]

No type mentioned.

An educated guess; reversionary modes are conservative and won’t operate as close to limits therefore you take a performance hit.

[Manicured garden]

Thanks Pit Bull. Added type; B738. That's a good guess, probably the reason is this but; any official or %100 correct explanation? It could be for single-engine case or power setting wouldn't be correct for TO thrust with manual calculations? these are questions running in my head.

[tdracer]

The thrust lapse rate in alternate mode is not the same as it is in normal mode. In simple English, that means that the change in N1 (and hence thrust) with forward speed and changing altitude isn't the same in alternate mode.
The penalties for EPR engine in alternate mode tend to be greater than N1 rated engines, because not only do you have different lapse rates during takeoff there is greater uncertainty in thrust when setting power on an EPR engine using N1.