737-800 FMC - Cutback & Thrust Bump

[TotalBeginner]

I have some questions regarding the 737-800 FMC.

Can anyone explain what Cutback is? Is this an airline specific option?

What are the differences between "Bump Option" and "Full-Rate Option" when selecting takeoff thrust bump?

When using an assumed temperature takeoff, why is this displayed as D-TO on the MFD, while a derated power setting is displayed as R-TO? Wouldn't it make more sense for this to be the other way around? What does the 'D' signify?

[RTO]

Cutback: Is part of the Boeing Quiet Climb System. Never seen it anywhere in real life but it is apparently a noise abatement option.
Aero 21 - Quiet Climb (http://www.boeing.com/commercial/aeromagazine/aero_21/quietclimb_story.html)


My guess on the 2 next ones is,
"Bump Option" You can bump TO thrust to 27K (no assumed temp avail) the few times its needed. (cheap option) default thrust is 26K

"Full-Rate Option" Default thrust is 27K, can use assumed temp and derate to 26K or 24K (expensive option)

[Sciolistes]

Full rate refers to the thrust selection in the FMC N1/LIMIT page for T/O thrust, either 26K or 27K depending on the engine rating.

"T/O Bump" is I think old terminology for a 27K T/O. In the latest FMC, to acheive the same thing you just select 27K option in the N1 LIMIT page.

Regardless, after T/O the amber N1 bug reduces back from 27K N1 to 26K and remains 26K N1 for the remainder of the flight.

However, even with a 26K engine, fire-walling the throttles past the amber bug gives 27.3K.

So in summary, all engines are 26K, except that some can be rated for 27K for T/O only.

[TotalBeginner]

Very informative. Thanks very much!