Originally Posted by
NickLappos
Good comments, Max, with one exception:
Strong engines run cool, weak ones need more temp for the same power (thus weak ones reach temp limits earlier, at lower power.)
Also, before I would have a mechanic do anything, I would perform power assurance. If both engines pass, stop all worry and just fly.
Nick,
This is exactly the difference I was trying to illustrate. There is a difference between engine calibration and engine health. I can take a perfectly healthy engine and calibrate it to make more power by closing down the NGV and it will run hotter. Then I can take the same engine and open the NGV and make less power but with less temp as well.
Example:
1) 98% N1 = 80% Tq at 800 C
now open the NGV on the same engine
2) 98% N1 = 75% Tq at 750 C
However as you stated engine health is different. If an engine has turbine rub, erosion, etc it is now a health issue and will in fact require more fuel and therefore more temp to reach the same power.
Example:
1) 98% N1 = 80% Tq at 800 C when engine is healthy
2) 98% N1 = 75% Tq at
850 C !when the engine has erosion, rub etc.
I run into this often where someone claims an engine is unhealthy when in fact it just isn't calibrated to their liking.
I agree though that first step would be a power check however I would look at the engine trend also and not just the latest numbers. An engine can still pass a power check but be on it's way out and letting you know it the whole time but if you don't look at the trend you won't identify a problem until you fail the power check and probably ground the machine!
Max