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ddhix

Low TIT, High Torque, High Fuel Flow

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Had an issue today, figured I would share:

Went up on the red ball, the crew showed me the following:

#4 Engine:

*TIT set at 900deg.

*Torque was significantly higher than the rest, can't remember by how much, but definitely very much higher.

*Fuel Flow was about 250-300lbs higher than the rest.

Of course they showed me other things they thought may have something to do with it, taking it to null, showing me top of beta, etc.

I asked if throttle alignment looked good, the FE looked over and said "yeah man it's lined up." I told them to shut it down.

Originally, I planned on doing a Rig Check, and TD Amp Test. Further thinking about it though, I realized one thing:

*I changed the #4 engine TIT gauge only a few days ago.

I decided to run it. First, because the torque was so high, I did a Torque Cal on all four Torque gauges; the #4 torque gauge was definitely too high, but not high enough, and did not explain the added fuel flow at 900.

Pushed them up to 900, noticed that the #4 throttle WAS out of alignment, by approximately 1 knob high, torque was still higher (but a bit better since it was properly cal'd), and fuel flow was still high.

Swapped the #3 & #4 TIT gauges. Pushed them all back up to 900. Now the #3 was 1 knob high.

Changed defective TIT gauge. Problem solved.

Did full TD Sys Ops Check for fun, all good.

I love it when it's simple but appears to be a full day of pain.

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Low TIT, High Torque, High Fuel Flow

Is a subject well explained in “SERVICE NEWS†vol.18 no.4 and vol.9 no.3

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This topic is very popular with our engineers. It seems that they are constantly bombarded with this "bad thermocouple" issue when at the simulator and at systems refreshers. While I agree that this can be a problem, unfortunately they don't ever seem to get told about the other causes of problems like this. Every "high torque" instance becomes a thermocouple problem. It is kind of funny, too, that we tend to get out the yellow box for low power write-ups, but that is a subject for a different thread.

Good going on the indicator problem. You saved yourself a whole bunch of time.

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Quoting:

I asked if throttle alignment looked good, the FE looked over and said "yeah man it's lined up."

Quoting:

Pushed them up to 900, noticed that the #4 throttle WAS out of alignment, by approximately 1 knob high, …

So the issue is:

Flying crew misleading maintenance crew, and the issue is not as the title/defect raised; Low TIT, High Torque, High Fuel Flow at same throttle position, but actually the reading was given at 1 knob high of #4 throttle (as been caught during the run-up by brother ddhix) .

So, pulling the one knob back will certainly correct the fuel and torque issues and you will be left with “Low TIT Indication”.

Main point: Do we have to believe them on any write-up or we should do our full engine-run before starting to hook-up any boxes or do any adjustment?

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So the issue is:

Flying crew misleading maintenance crew

I know exactly what you mean. I fixed an aircraft yaw by swapping gauges, and the problem never came back.

Apparently it wasn't yawing afterall.

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Its a knowledge problem.

Good thing they can do what the pilots and navs are for and read TERPs but dont have a clue about the 1/2 knob limit.

Bad and missing knowledge goes on with both side of the fence so dont just beat on the zipper suited sun gods, but yeah it would really irritate the crap out of me when one of my guys would do something like that. It would really PO me if it was something I had already taught them, and it would PO me if it was something that I failed to teach them.

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Hopefully this wasn't an "Us vs Them" post. ;-)

Whether the crew was correct in their troubleshooting or not there was still an indication problem. So in reality the crew was correct to write something up. Generally speaking one knob width on the throttles should not be enough to "Red Ball." That possible simple TD system issue is not worth it but.....? They had other indications so the writeup was proper as indicated by your gauge swap. In reality this problem was probably worse than a possible TD system malfunction. All we have is the indicators. Really of all the engine indicators the FF gauges were the ones I trusted the most.

Good on you to test gauges early on. I can tell you I've swapped plenty of gauges myself as aircrew. In flight even!!

I will say if you were around during the aftermath of the Colorado Springs crash you'll see why "Aircrew" can a bit leery with engine indicating problems. Taking the Pilot/FE knowledge levels into consideration it's better to be safe than sorry.

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jbob thanks for those comments, all so true - but just to add my 2 cents...

Why the raggin on a flight crew for following flight mannual procedures based on what they observed?

How about working together to solve write-ups like this; was there not time to do a run-up with the crew to see what they were looking at?

Based on the knowledge level of some of the younger FE's out there I'm surprised they caught it. I'm not knocking theses guys they're busting their butts to learn "C-130", but some of the younger FE's never turned a wrench or smelled T-56 exhaust before they got to FE school. How about some of you seasoned maintenance types cross-training and bring the valuable insights to the "crewdog" world.

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There is or was a chart in the front of the -1-1 that would allow the FE to determine which gauge was wrong, I used it all the time before placing the write-up in the 781. What happened to it? I too trusted the fuel flow first, plus it could also be verified with the fuel quanity indicators over a set period.

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Good going ddhix. I think you have demonstrated the value of a good troubleshooting engine ground run. I have always believed, particularly with the Herc, that if on an engine troubleshooting ground run you ask the aeroplane the right questions it will give you the right answers, or at least point you in the right direction.

Rgds to all

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Aside from the fuel costs, if I remember correctly, the instrument shop should have a H261-11. You can use it to test an indicator if you can't run an on-wing swap.

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I will say if you were around during the aftermath of the Colorado Springs crash you'll see why "Aircrew" can a bit leery with engine indicating problems.

I had been writing problems like this up for years prior to the C-Springs accident and got the deer in a headlight look for many of my contemporaries, they just couldn't figure out whey I wrote it up. Knowledge is a valuable thing, CORRECT knowledge is an indispensable thing.

Something that is rampant in both the MX and OPs side is incorrect knowledge.

People "knowing" something because their trainer or instructor taught them that way, but unfortunately their trainer/instructor taught them wrong, simply because they in turn were taught wrong by their instructor and so on.

There is really no getting around this type of "incorrect" knowledge issue, simply because its part of human nature to trust what is taught, (unless you a cynical, untrusting, question everything kind of bastard that is).

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Hopefully this wasn't an "Us vs Them" post. ;-)

Whether the crew was correct in their troubleshooting or not there was still an indication problem. So in reality the crew was correct to write something up. Generally speaking one knob width on the throttles should not be enough to "Red Ball." That possible simple TD system issue is not worth it but.....? They had other indications so the writeup was proper as indicated by your gauge swap. In reality this problem was probably worse than a possible TD system malfunction. All we have is the indicators. Really of all the engine indicators the FF gauges were the ones I trusted the most.

Good on you to test gauges early on. I can tell you I've swapped plenty of gauges myself as aircrew. In flight even!!

I will say if you were around during the aftermath of the Colorado Springs crash you'll see why "Aircrew" can a bit leery with engine indicating problems. Taking the Pilot/FE knowledge levels into consideration it's better to be safe than sorry.

I was around then a know the said ACFT and crew well. Chief Vail was a family friend . Summit 38 was a tragic loss. If anybody WIKI's the Summit 838 accident there are a few inaccurate pieces in that write up. Not fun being at the wrong end of a accident investigation board. Anybody that would like to know more just ask.

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I was around then a know the said ACFT and crew well. Chief Vail was a family friend . Summit 38 was a tragic loss. If anybody WIKI's the Summit 838 accident there are a few inaccurate pieces in that write up. Not fun being at the wrong end of a accident investigation board. Anybody that would like to know more just ask.

Can't seem to find it, so I'm asking ...... Maybe start a separate thread ......

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