CFM56-7B question..

[RYR-738-JOCKEY]

Here's another one for you guys. What is the maximum thrust for a
26k-option engine? I thought this engine would produce a maximum of 26k, regardless. But reading our FCOM it clearly states: "The full rated takeoff thrust is available at a thrust lever position less than the forward stop." ,and..."The maximum rated thrust is available at the forward stop. The EEC limits the maximum thrust according to the airplane model as follows: 737-800 - CFM56-7B27 rating." How shall this be interpreted? 26k with A/T, 27k when firewalling???? Thanx in advance :ok:

[POL.777]

http://www.pprune.org/forums/archive/index.php/t-121829.html

And another one

http://www.cfm56.com/index.php?level2=engines&level3=cfm56-7&level4=1056

Hope this helps.

[RYR-738-JOCKEY]

Thanx for that. But after reading them, I find myself at square 1 again. It seems everyone is of the impression that Maximum available thrust (at the forward stop) is the same as Maximum rated, ie according to option/package..22k,24,26 or 27-bump.

So, would anyone care to enlighten me. Will I get 26k, or 27k at the forward stop in a RYR aircraft..?

[POL.777]

According to this link http://www.b737.org.uk/powerplant.htm#Engine_Ratings
You will only get fullrated thrust.
However when the EECs are in (hard) ALTN mode, you will be able to overboost the engines.
Copy paste from a 738 FCOM
If the EECs are in the alternate mode, advancing the thrust levers full forward provides some overboost and should be considered only during emergency situations when all other available actions have been taken and terrain contact is imminent.
So what do you get when you firewall the engine on a RYR aircraft (in hard altn mode)? Don't know - a bit extra thrust I should think.
:confused:

[Blinkz]

I fly for RYR as well and I was under the same impression as Pol. If you firewall the throttles then you will get max rated thrust as the EECs take care of it all. When the EECs are in hard alt mode then you will be able to overboost the engines and get more then max rated thrust (at the risk of damaging the engine)

[RYR-738-JOCKEY]

I believe you're right. But Blinkz, what about the text I've quoted from our FCOM?

[Blinkz]

I don't remember reading that bit specifically, however my guess would be that it is correct. You DO get full rated thrust at a position less then firewall.....the point is that past that position the EECs limit the engine to max rated thrust.