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torque flux with no other indication


ec130
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  we have had a reoccuring problem in which the torque will flux well over 1000 in lbs sometimes it just one engine sometimes its two never the same ones though..there is no change in rpm tit or fuel flow..havent been able to duplicate the problem on the ground and the flight crew claims there isnt even a slight yaw at the highest peak of the torque flux..?? stumped on this one. anyone??
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Treat it as an RPM flux and think Synchrophaser system since it is more than one engine involved. Also, make sure all 4 engine mechanical RPM's are within .20% of 100%. If you're on an EC-130, you might have electrical shielding problems around your Sync, but I'm just grabbing at straws. If you're US Air Force, you probably don't have problems with clogged filters or dirty fluid.

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Disconnect the leg between the torquemeter pickup and the engine firewall. The firewall and the wing splice (that does mean taking the leading edge off). Then from wing splice to flight deck. Check the connectors then the wires with the Eclypse Plus tester or Fluke meter. We found the splices at FS245 bad and replaced them. This was for a fluxing gauge.

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T/m indicator power supply problem would be my first guess.

Ess Ac Bus is the common source for both the synchrophaser and the Ac instrument Bus (Torque meter indicator) and both of them very sensitive to power source; a good idea to switch "off" no 2 generator during the malfunction to isolate the defect.

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A long time ago I had something similar. The only thing I found

out of the ordinary, was the t/m housing was filled with oil. The

t/m was replaced and the problem went away.

More recently, a break in the insulation between the reference

coil wires in the QEC kit also gave a fluctuation

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My only reason I believe in treating this as an RPM flux is that the problem moves around to all 4 engines, and often times the RPM indicators can be too stiff to follow a 1000 in-lb torque flux. The only real way to isolate whether RPM is truly fluxing with Torque or not is either with an Accutach or checking Freq's coming off the generators.

Of course, if the RPM is indeed Rock Solid on the Freq Meter and/or Accutach (I understand it cannot be duplicated on the ground), it would most likely be a power issue somewhere that connects all 4 indicators together.

If the Generator frequency is fluctuating with Torque afterall, it could be anything in the Synchrophaser system, including power source and Constant Voltage Transformer. In case it helps someone, the CVT was added via TCTO 1C-130-1309. It would also be pulse generator wiring on a selected master prop, or a Tach Generator sending errant signals. It could be lots of things.

Just another idea, you might trigger the radios during your ground run, as well as activate all the avionics used in flight and operate the engines at power for as long as the aircrew does when they get this problem. I've seen a lot of other outstanding ideas come out here, lots of great experience is on the table. ec130, please let us know what you find. It could help someone else down the line.

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...Just another idea, you might trigger the radios during your ground run,...

Very good idea, depending on the HF you have installed it could be putting out several hundred watts of power. (One of ours puts out 400 watts peak.)

Turn your prop ice system on and see if you can duplicate...

(Our OLD operators manual had a note about "flux" of the Tq and or TIT gages when the Prop ice system was "ON"...)

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... depending on the HF you have installed it could be putting out several hundred watts of power. (One of ours puts out 400 watts peak.)

Good old HF radios - I'd forgotten about these. Yes, 120 watts AM, and 400watts on sidebands. I remember them causing some strife for me many years ago ......

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  • 3 weeks later...

we did eventually figure out what the issue was..remember how i noted how the crew had no indication of yaw at the highest " indicated " torque flux? well anyways..it took a lot of teamwork from electronics and us to figure out what the problem was..there was a ground wire to the inverter that would randomly short out that was causing the guages to go sporatic.. i think this is why we had such a hell of a time duplicating this one on the ground..after a valve housing change, dome seals, standby filters, syncrophasers and torquemeter pickups this is what eventually fixed it..go figure right

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yes we did eventually figure out what the issue was..remember how i noted how the crew had no indication of yaw at the highest " indicated " torque flux? well anyways..it took a lot of teamwork from electronics and us to figure out what the problem was..there was a ground wire to the inverter that would randomly short out that was causing the guages to go sporatic.. i think this is why we had such a hell of a time duplicating this one on the ground..after a valve housing change, dome seals, standby filters, syncrophasers and torquemeter pickups this is what eventually fixed it..go figure right

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we did eventually figure out what the issue was..remember how i noted how the crew had no indication of yaw at the highest " indicated " torque flux? well anyways..it took a lot of teamwork from electronics and us to figure out what the problem was..there was a ground wire to the inverter that would randomly short out that was causing the guages to go sporatic.. i think this is why we had such a hell of a time duplicating this one on the ground..after a valve housing change, dome seals, standby filters, syncrophasers and torquemeter pickup, and a pulse gen this is what eventually fixed it..go figure right

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