tpe 331-8 hot section?

[500and2]

what are the indications that an engine may be in need of a new hot section?

higher than normal ITT?.....Torque,etc?....

one of our engines doesn't seem to be producing "book" performance #'s anymore...... our TAS is also lagging ~18kts from book value.

I know that the -8 engines suck and we should just upgrade to the -10's..... but it's a money issue... among other things.

if you know garretts, please PM me... I have some more questions!

thanks,

500and2

 

[avbug]

You want a diagnosis based only on ITT being higher than normal? Your torque is higher than normal? What does that mean?

The only way your torque is higher than normal is if you're pushing the power up too high, and that would explain high ITT/EGT. If your torque is low and your ITT is high, have you consulted the mx manual? What else is the engine doing, and what other parameters have you seen? How is fuel flow compared to normal operation? How long has the engine been this way, and have you seen any changes? What changes do you get, and what inidications, when coming back on the speed lever? In flight? On the ground? When was the last compressor wash? Under what conditions are you operating? Have you checked the inlet probe for debris or dirt? Condition of propeller? On what aircraft? Has your airspeed indicator been calibrated lately? Nothing known here, more details needed.

 

[Say Again Over]

(not a mechanic here) How often you change out or flow check the nozzles, we had extra fuel nozzles and used to change them out on a regular basis to do a flow check and cleaning, is your EPA kit still working properly (slight RPM increase at shut down), be sure to do the prop spinning to help keep nozzles from coking up. Torque gages are terribly inaccurate, if you had been doing trend monitoring it would be a big help to monitor degradation, FF vs TAS and ITT are the best indicators.

How long have you operated the same aircraft, Merlin III? GPU, Nicad, lead acid? Starting is very critical on the 331, we had our own GPU.

When you get he problem fixed I would reccommend doing trend monitoring every flight and also a good idea to have one extra set of nozzles and a jig to flow check them. Also, make sure you allow a three minute cool down period before shutting down.

 

[500and2]

good info, thanks

Thankyou Avbug and Say again.....

I just fly the plane (C441), so I'm passing on your advice to our trusty mx squad. They are not all schooled on the conquest, so learning curve is steep at this point.

FF at altitude is only about 20-40# lower than book value.... but TAS is suffering by 20kts.....

Mx will be calibrating torque and EGT compensators early in the "fix-it" process.

I have a lot of operating experience with pt-6's and have never seen such a similar degradation of performance (20kts)..... so was looking for any Garrett specific "signs" of HOT SECTION,etc issues.

-C441 with the -8 engines

"IF" our gauges are calibrated correctly... here is what we're seeing on climbout:

on climbout through about 16,000 the left and right engines are Torque limited at 1,669#....The left engine begins to be ITT limited (450 degrees) while the right engine maintains about 50-100 degrees cooler.....

at cruise alt (25,000) the left engine is around 1550# torque... with EGT at 440-450 degrees.... FF is ~280#/hr......
the right engine is matched at 1550# torque but still hasn't tempted out.... the EGT is down around 350-400 degrees.... FF is ~280#/hr

KIAS is 200.....TAS is 170

KIAS and TAS "SHOULD" be 20kts higher at the same altitude/temp per book charts.

The Garrett Tech's have been contacted.. and we're getting to the bottom of this......

Thankyou for your advice and suggestions.

Merry Christmas
500and2

 

[Hammerfall]

Also look for Bleed air leaks at the blanking plates, check your prop blade angles, and verify your engine rigging. look at what numbers you get in full reverse. This is the only place you have a fixed blade angle (provided you are rigged correctly) compare your temps,torques and fuel flows. How much time since last shop visit? Is it hard time motor or CAM?

 

[500and2]

thanks

Thanks for the tip, I'll pass it along to mx.

500and2