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View Full Version : CT7 on Saab340 - cruise power


Dufo
20th Oct 2008, 21:46
I was wondering what other companies use for climb and cruise power. We operate a fleet of 340A's and use original performance tables from flight manual (dated somewhere in 1988). As I know, General Electric regularly issues revisions regarding operation and maintenance practices and something must have changed in the last 20 years.
780-800 deg. C in cruise (with engine anti ice off) seems rather low.. and I know that at least one company operate at 830-840' C with the A model.
Any hints?

Jernej

barit1
20th Oct 2008, 22:42
Hot section life depends greatly on turbine temp. If you run hotter, you can count on shorter TBO and higher hourly costs.

Have you talked to GE Flight Ops Support?

ftp
21st Oct 2008, 02:52
Wow, you're running them at 780! Don't tell me you climb with that temp.

Here's how we run our engines, CT7-5A2, on condition engines.

Our temp limits are 820 below 15,000 and 840 above 15,000 with E AI off, add 10 degrees with E AI on. We use tables to set torque and the temp limits are considered maximum values under normal operating conditions.

I've been told that the tables we have are from GE and are used to extend engine life. With most of our engines we are somewhere between 10 to 40 degrees cooler than the company temp limits when flying with charted power. (some engines are exceptions and we are limited by temps)

We are also recommended to stay below 75% at low altitude to save fuel. This would give about a 740 ITT.

dkz
21st Oct 2008, 07:48
For the 340B we used 840 below 15k and 850 above that (with A/i or without, the limitation remained). On a cool day we would use the torque charts and the temp would be somewhere in the 780-800 range.

hope it helps, don't know about the A model, never touched it.

P.S. - Former company, green logo in EEU ;)