Hi cyclops camel,
Thanks for the reply.
Here is what the book says about leaning the mixture:
"If TIT limit not exceeded, lean to recommended fuel flow."
That is all it says. The TIT limit, by the way, is 900 degrees C and can only be checked if the TIT gauge has been calibrated properly, which is not necessarily the case in our Duke.
As can be seen, there is nothing stated about leaning with respect to EGT or TIT. There is no EGT gauge, only the TIT.
When the book says "... the recommended fuel flow" it can only be talking about the book figures.
Try to lean to the book figures in our Duke and you will experience severe rough running!
The fuel flow (digital), MP and fuel control units have all been checked out OK, btw.
Thanks again,
Tom Atkinson