Topic Author
Posts: 1339
Joined: Thu Jan 13, 2000 3:58 pm

Derated Thrust

Thu Sep 28, 2000 10:38 pm

I was wondering at the other airlines, what is the maximum derate used? (ASMD Temp).

At Ansett, 60°C is used on the B762. That is about 95N1 at 15°C.


Posts: 1066
Joined: Fri Mar 16, 2007 1:29 pm

RE: Derated Thrust

Sat Sep 30, 2000 9:13 am

I believe the FAR's/CAR's/CAA etc specify minimum derates. Our company 757's (RB211) use data supplied by Jeppesen and for the most part, the highest assumed temperature allowed is in the 60-62C range. The maximum assumed tends to decrease with ambient temperatures lower than 20C.

Just a thumbnail explanation!

Best Regards,

CX Flyboy
Posts: 6086
Joined: Sun Dec 26, 1999 6:10 pm

RE: Derated Thrust

Sat Sep 30, 2000 1:30 pm

We can use 60 degrees as well in Cathay on the 747-400.

The Hong Kong Civil Aviation Department restricts derates to not more than 25% of fully rated thrust. This is why airlines, including ours quite often has engines derated in the certification process (Done by altering the computer programming in the aircraft), so that we can have a bigger derate, and in the long run save money.
Posts: 2115
Joined: Tue May 18, 1999 3:49 am

RE: Derated Thrust

Sat Oct 07, 2000 10:54 pm


What is meant is the temperature below the normal at the end of the turbine. Is that is?

Thank you,

Best regards,
Alain Mengus
Posts: 3140
Joined: Fri Jan 21, 2000 11:51 am

RE: Derated Thrust

Sun Oct 08, 2000 2:57 am

Last I knew AA 767s=60C max assumed temp (AT) and 757s=62C AT.
MD90s=60C AT on virtually all flights.

*NO CARRIER* -- A Naval Aviator's worst nightmare!

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