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#3 TIT 30C higher at same fuel flow settings


edwardlcy
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HI all, C-130H having this snag #3 TIT 30C higher compared to other engines at same fuel flow settings across all throttle range, TQ and rpm are normal though..

Rectification done:

- TD Amp calibrated and adjusted

- TD amp replaced and calibrated

- TD valve replaced

- 18 thermocouples replaced

- thermocouple harness replaced

- TIT indicator replaced

- ECTM converter replaced

- coordinator cx satis

- anti icing valve func cx satis

Snag still persist

Any ideas?

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What about T-block and Y-lead? I realize this is a long

shot (and difficult), try swapping the indicator and amp

wires around on the T-block - only allowed 6·C difference

at same throttle position. Also try disconnecting at firewall,

gauge, and T-block, then do resistance checks between the

chromel-alumel wires and also to ground. In all cases there

should NOT be any continuity . . . .

Something else to try, use your TD tester to shoot TIT signal

to cockpit

Good luck, let us know what you find

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What about T-block and Y-lead? I realize this is a long

shot (and difficult), try swapping the indicator and amp

wires around on the T-block - only allowed 6·C difference

at same throttle position. Also try disconnecting at firewall,

gauge, and T-block, then do resistance checks between the

chromel-alumel wires and also to ground. In all cases there

should NOT be any continuity . . . .

Something else to try, use your TD tester to shoot TIT signal

to cockpit

Good luck, let us know what you find

sorry but what do you mean by T-block and Y-lead and wheres the location? and by chromel-alumel wires are they the ones connected to thermocouples?

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A little new to these engines then? Okay, T-block is located on the upper left side of

the combustion case - used to connect the two thermocouple harnesses together. Next,

the Y-lead - takes the signal from the T-block through the fireseal, and then splits to connect

to the TD amp, and back to the firewall for the indicator signal.

T-block part no: 6840004

Y-lead part no: 6847718

By the way, what is an 'ECTM converter' .......?? Another question: are the throttles lined

up above X-over?

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.......I suppose you checked it out in Null.........and no throttle split!!..........I beleive that above crossover, you're on Temp schedulling.

Maybe the TD system reads the right temp but, not the indicator. Keep on diggin' boy!! Find that little bastard snag!!

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Did this engine just suddenly get 30C hotter? Is there a baseline for this engine? EWngines wear and as they do they run hotter. Is this engine out of limits? If it is a sudden increase in temp the thermocouple system may be in question, but don't forget to look for bleed air leaks. Does this engine have a trim thermocouple? If so it may also have a trim resistor.

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Haha, that's an easy one. Check your bleed valves. Close your engine bleed then check the engine anti-ice to see if you get a 24 degree rise. If you get less than 24 degrees TIT rise, lets say it only rises 18 degrees you have a stuck bleed valve, if you get no rise at all your anti-ice valve is stuck open or your bleeds are just stuck open.

Check it in null too.

Does it have oil cooler augmentation?

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Haha, that's an easy one. Check your bleed valves. Close your engine bleed then check the engine anti-ice to see if you get a 24 degree rise. If you get less than 24 degrees TIT rise, lets say it only rises 18 degrees you have a stuck bleed valve, if you get no rise at all your anti-ice valve is stuck open or your bleeds are just stuck open.

Check it in null too.

Does it have oil cooler augmentation?

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Perform all the TD system checks with the engines running. Max Start TIT, Crossover, Max Auto, Temp Limiting (leach all the air off that motor that you can in order to get it to overtemp.) If all those checks are normal, then your TD system and Indication systems agree with each other.

Did you do a Torque Cal on all 4?

You should only compare all 4 engine TIT's and torques with bleed air valves closed.

Hooking up the TD tester to the firewall TIT harness is a step I love using when troubleshooting these write-ups.

What else has been done so far?

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Haha, that's an easy one. Check your bleed valves. Close your engine bleed then check the engine anti-ice to see if you get a 24 degree rise. If you get less than 24 degrees TIT rise, lets say it only rises 18 degrees you have a stuck bleed valve, if you get no rise at all your anti-ice valve is stuck open or your bleeds are just stuck open.

Check it in null too.

Does it have oil cooler augmentation?

Not true: bleed valves will not affect TIT rise at LSGI and NGI, below X-over, or in NULL. The

24°C rise is created when scoop anti-icing and inlet anti-icing are functioning correctly. A lesser

rise will indicate one or both a/icing side valves, and/or a/icing solenoid valve inop and/or scoop

valve inop.

Now: the only way to figure out what's happening is to do man-on-stand. Start engine, and at

NGI, lightly touch fingers to side valve(s) and feel if they're hot: if so, valve(s) are open. If cool

have cockpit open engine a/icing for a minute, and touch again. If still cool, valve(s) are closed.

In either case the problem may lie with the side valves stuck open/closed, or with the solenoid

valve which controls them being inop.

A hand held over the scoop vent on the RHS of the inlet duct will tell you whether the scoop valve

is functioning as required.

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To get back to the origional problem, my feeling is a wiring problem. Maybe a

dry joint in a cannon plug at a pressure break, firewall, in a lead. Having reread

the original post, he does says at all power settings ...... torq should not be

used as a comparative reference as a 98% engine wil have much less torq than

a 108% engine, especially once throttle is above x-over. If the TD systems on

symmetrical engines are good, TIT should be near identical with throttles above

x-over lined up. Fuel flows on engines should be very close, but may differ for

a number of reasons. RPM should be 99.75% to 100.25%

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Hey Ben!!........you mean to tell us that if you get an oil temp augmentation,......you get a TIT augmentation!! And also I'D like to mention that Yawdamper makes sense too with bleed air leaks and old age engine(just like me as a matter of fact). #3 is always the first one to get the kick in the ass to start and to wake up the other ones after!!................John Boy

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Hey Ben!!........you mean to tell us that if you get an oil temp augmentation,......you get a TIT augmentation!!

Yes, actually, you do. The more bleed air systems you run off a motor, the higher the TIT is. Air valves go bad all the time, and oil cooler augmentation comes right off of the diffuser. I think what he was getting at was was just to check the augmentation system for leaks if it comes equipped.

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