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Engine TIT Flux


joshdegroa
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Were having an issue with one of out C-130T engines. We had a flight come back with a #4 engine TIT flux of +/- 40 Degrees in the air, and +/- 5 degrees on the ground when #4 prop anti-ice/de-ice switch is turned on. Both indications happen in auto or Null. When the prop anti ice is turned off TIT returns to steady and solid. Any ideas of what it could be?

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I was thinking along the same line, but they get power from two different sources. The A/C Instrument and Engine Fuel Control inverter recieves power from the Essential D/C bus in flight, unless they have it switched to the Essential A/C power position, while the prop anti-icing receives power from the RH A/C bus. Unless there is a grounding issue, the only thing the two systems could possibly have in common are cannon plugs.

Is the problem there in Null? Switch the invertor to the other position and see if it duplicates. You said you "Were having an issue". Does that mean it was already fixed, or just not duplicating anymore?

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The discrepancy still remains unfortunetly. It happens regardless if T.D. is in AUTO or NULL. Yesterday when we were turning, as soon as the #4 Prop Ice control switch is activated, the #4 TIT drops 10 degrees, and then flux +- 5. We're going to try and swap guages when we turn, since we had to replace the #3 TIT guage(froze up while turning last night).

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The discrepancy still remains unfortunetly. It happens regardless if T.D. is in AUTO or NULL. Yesterday when we were turning, as soon as the #4 Prop Ice control switch is activated, the #4 TIT drops 10 degrees, and then flux +- 5. We're going to try and swap guages when we turn, since we had to replace the #3 TIT guage(froze up while turning last night).

NO movement in the other gauges?

What year aircraft are we talking about? (I would think an OLD aircraft E Model era?...)

I guess there is NO movement in the "other" instruments to indicate a "true" flux.. or is there? (fuel flow and/or torque?)

If this is an OLDER aircraft this is a "Normal" indication so much so that it (the TIT gauge movement ) was added to our NATOPS (-1) (Operators manual) in the form of a "NOTE".

I can get you a direct quote next week... This would be from a 1979-84 USMC NATOPS for an F model...

If the issue just started I would look at the shielding on your wires for the TIT gauge.

The large amperage is inducing "noise" which causes the "flux".

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  • 2 weeks later...

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