TFE731, a blender.
Has a bunch of stages for sqeezing stuff, both axial and centrifugal... great for ears.
Has a bunch of bunsen burners, the compact kind...
has a set of HPT and LPT, that drives the blender at the front through a RGB. The very first (maybe) geared turbo fan. Yaay.
Shows N1, N2, ITT, F/F etc,
Has levers to the FCU & a DEEC that controls N1, which has some limited authority
Issue is...
Matched engines....
N1/N2/FF and thrust lever, all match, with DEEC on or off, and plane drives in a straight line (disregarding my version of IF)
ITT, 25C higher on one engine.
match ITTs, got a stagger of everything, N1/N2/FF and Thrust lever are all low on the high ITT side. Add rudder trim to keep face off the side windows.
Swap ITT gauges, issue stays with engine.
Swap engine positions, issue follows engine.
Borescope the inny bit, clean, burners same. Engine to engine, summa summa.
Surge bleed valves... through shop with engine and apparently OK.... (but not verified independently)
So...
I've had bad thermocouples on jets before, most of the time they gave low EGT/T5/TOT/ITT.... Is there a mode of degrading of the thermocouples that causes an increase in indicated temp? Sitting on a cold plane, they are within 1 degree.... the issue arises at idle, and remains almost constant differential up to full thrust.
My confusion arises from ever bothering to own aircraft. Except for the Pitts, and maybe the T28B, one cuz everyone should fly a Pitts particularly single-seat ones, and the other as starting an 1820 is a lot of fun.
A degradation of aero path in an engine should exhibit an increase in ITT, FF and also change N1/N2 relationship (well almost always for the last one)
I passed this issue past the OEM, and got blank stares for my efforts. The response is that it is within limits, which is only true to a certain point, as we are affecting thrust output when we use an ITT setting rather than an N1.
Anyone with an answer to the observations shall not go unpunished.
