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Aero Precision provides OEM part support for military aircraft operators across more than 20 aircraft

Lkuest

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core_pfieldgroups_3

  • core_pfield_11
    Went to LRAFB in November 2002 working as an engine specialist on the flightline at the 314 AMXS/Blue AMU. In May 2011, started working as an FTD instructor at Yokota AFB, Japan. Arrived back at 314 AMXS/Blue in 2014.
  • core_pfield_12
    LRAFB
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    C-130H Propulsion

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  1. If the orifice cups are clogged, you will never be able to accurately check servicing, as the pressurized sump may always show good, but at the expense of the atmospheric sump. The atmospheric sump is allegedly the most accurate location, so if it's inaccurate, it will always lie to you. You should check your tech data for how to clean the orifice cups. The only other option is to replace the pitchlock regulator, preferably with one that was recently overhauled to guarantee the cups are clean. One indication the orifice cups are clogged is that, when you check the pressurized sump after 2 minutes, the fluid fills up and overflows. This is due to the pitchlock regulator keeping the fluid pressurized in the system instead of draining the fluid into the barrel like it's supposed to. Be careful of those who tell you only the pressurized sump is required for an accurate fluid check. This comes from the idea that the pressurized sump dipstick actually gives you a quantity, and the atmospheric sump is only a go/no-go. The only thing the pressurized sump dipstick tells you is how much fluid is in the pressurized sump, who's job is to force-feed the pumps sending the fluid out to the valvehousing. The atmospheric sump dipstick tells you how much is in the barrel AND atmospheric sump. If there's nothing on the atmospheric dipstick, you have no idea how much is in the barrel, and that can be dangerous.
  2. It is likely your orifice cups are clogged, preventing proper filling of the barrel assembly, and therefore your atmospheric sump
  3. This sounds strange. I'd almost suspect you had a bleed valve stuck open on one of the other engines, or there may be a wiring problem within the anti-ice system that is affecting indication. Does the engine pitch sound like it's roaring to life? Does the aircraft actually yaw a bit in the direction of the increased torque indication? I would also be interested to hear how all 4 engines behave together when all bleeds are open and the wing & empennage are actuated. Please, for clarity, when you say TIT remains the same, can you please specify whether the TIT momentarily moved up/down and corrected, or did the TIT simply not move? Can you verify the wing and empennage valves have proper function. Please clarify how much each indicator is moving when wing and empennage anti-icing is actuated Really, the only reason for torque to significantly increase with a steady TIT is the engine suddenly becomes more efficient by retaining more air within the engine, or the indication is lying.
  4. does this happen with only that single engine bleed air valve open, or are all 4 engine bleed air valves open? Do you have dummy bleed air valves, or bleed air regulator valves?
  5. I recommend checking the NTS gaps, Low Pitch Stop blade angles, and Torque Retaining Lugs for all 4 propellers, as well as note the results of the in-flight NTS checks.
  6. I agree with NATOPS, once the engine shuts down, any fluid pressure from the still-spinning pumps will go directly to the increase-pitch side of the dome via the feather valve and feather actuating valve until the pumps can no longer supply 100 PSI. Then the blades stop changing pitch. Since the internal seals for each propeller are worn differently, it's difficult to nail down a specific degree when you transition through that pressure. Also, as you are flying, airflow is still trying to spin the propeller beyond what it would be during a ground run. I doubt you will get all the way to feather, but you should get far enough to make sure propeller drag isn't dangerous. Think of the propeller as an air brake which either absorbs or transmits airflow energy. If the airflow is inadequate to continue spinning the propeller, then the propeller resistance to airflow is naturally going to be low. I am unfamiliar with the flight manuals, so purely from a maintenance standpoint I also want to emphasize that you will still have 28vdc attempting to actuate the propeller feather solenoid, so once the blades stop changing pitch, the propeller feathering circuit may still be energized, both overheating the circuit as well as sucking DC voltage if that bus is powered. Check your flight manual to see if you need to manually pull the feather override button up if the propeller blades stop changing pitch, but are not all the way in feather.
  7. I recommend your military request technical data upgrades. I've never even seen a 1C-130B-2-4, so I have no idea what information I could add to help you troubleshoot your problem. With updated technical data, you might be able to do this on your own. As with most fluctuations, it is much easier to recommend a maintenance action if I was able to see all the engine instruments. Just about anything can cause a torque flux, and "all wiring" is a pretty broad statement.
  8. I would be interested to know what kind of troubleshooting manuals you have available to you.
  9. I agree with pjvr. What you are describing is a throttle misalignment below crossover, for which there is no limit. If everything else is within limits, there isn't a problem. If you are still really concerned about this, you could check for air leaks, but you should also have lower torque and slower starts. You could also adjust the TD Valve and/or Fuel Control, but ONLY if the rich/lean check shows rich AND you have warm start temperatures and well within normal start times. Otherwise, it sounds like the TD system is doing its job well, and stops controlling when it's supposed to stop controlling.
  10. If TIT, Fuel Flow, and Torque are all low together with no change in RPM, whatever is causing the problem is definitely fuel related. Have you run an electrical check on all wiring? Some of the electricity goes through the LH engine wiring harness, and there is a J3 lead that can cause problems. You might also hook up the TD Amp test set and shake the wiring around to try to duplicate. You should also pull the lid off the junction box next to the TD Amp and see if anything looks out of place.
  11. Was RPM doing anything, and if so, which direction in relation to TIT? Also, were torque and TIT low together, or opposite each other?
  12. As a maintainer, I've seen this a few times, both with engine running and during static pitch changes. Also, with the throttle in any position, as well as reversing with the condition lever in feather. I've never had an aircraft from my unit reverse in flight during the 200,000+ flight hours worth of malfunctions I've either worked or got turnover for, but I do believe this eventuality is covered in simulator training.
  13. This really needs more detail. Try to describe the malfunction in detail so we can get a mental picture of what's going on. Torque dropped for only 2 seconds. Which 2 seconds? At the beginning of the 5 seconds that RPM was low? At the end of it? If torque and RPM dropped together, it would indicate air as a likely cause. If Torque stayed high when RPM dropped, then that would indicate a propeller malfunction, and TIT happened to shoot up due to the SCV opening at 94%. If TIT shot up only after RPM dropped to 94%, that would further indicate the propeller as the cause. If TIT shot up before RPM dropped, then that would point to an air malfunction. How did the engine recover? Did you turn off bleed air, adjust the TD switch, or did it come back on it's own? Is there a history? How many hours are on the compressor? You're also missing fuel flow, which might help indicate a fuel or TD system malfunction. You might also include much TIT and Torque moved, as well as the pressure altitude and outside air temperature. A very slight TIT increase might indicate it was fuel related because once the SCV opens, the TIT should shoot up a lot. A large TIT increase should eliminate fuel system as the cause. A SCV malfunction is usually only good for about 5000 in-lbs of torque at power and around sea level, but I'm sure the power loss could get much more severe at high altitude or hot conditions and engine wear level. There's just too many variables for us to be truly helpful with the little information that was provided.
  14. I'm assuming a BARV is a Bleed Air Regulator Valve, and when you say "accompanied of TIT", you mean TIT dropped with torque, and not increased. The TD Amp's job is not to maintain power, but to maintain temperature based on the throttle setting. If the TIT is low while the TD Amp is in AUTO, then there is an error with a signal being supplied to the TD Amp, or there is an error with the Amp itself, a setting or malfunction, When you lose air, you lose power for two reasons. Jet engines love more air, both to increase power through expansion, and also to keep the combustion chamber cool. If you lose air, you lose power immediately since there is less air to expand, but also the loss of cooling air causes an increase in TIT, and results in the TD Amp to pull fuel back. This all produces a loss of torque and fuel flow while maintaining TIT. I cannot emphasize this enough, before doing anything, ensure your indications are accurate! TIT to within 6 degrees of actual as measured with a test set and all thermocouples verified good and connected properly. Torque indicator recalibrated and set to within 50 in-lbs of actual. Swap the Fuel Flow gauge with a known good one for good measure, then reverify the problem. Why the engine goes to normal when the Regulator Valve gets turned off is interesting. If the TIT was to remain normal, I would say the Regulator Valve was mis-tuned and the TD Amp was doing its job. Since the TIT is also low, we know the TD Amp is not doing its job (above crossover only). Even if the Regulator was malfunctioning, the TD Amp is definitely having an issue. The fact that the valve affects the TD System operation means they may be connected electrically in some way, like the power/signal wires may be chafing together. If the fuel control was perfectly tuned and we suspected the TD Amp was just inop, we would see high TIT with bleed air open, not low TIT. To check if it is an electrical problem, check power going to the TD Amp using a TD Amp Test Set, then cycle the bleed air valve and see if the power at the Amp changes. There are two types of power going to the Amp, so check them both. If I misunderstood you, and the TIT is high during the malfunction, and not low, then you have a TD Amp malfunction AND a bleed air regulating valve balance issue causing you to lose 2500 in-lbs.
  15. Is the engine operating within limits? If so, disregard the differences as there is no limit for symmetrical operation in HSGI. Otherwise, you might consider checking rigging with the valve housing, or swap it with a known good valve housing, as long as the Fuel Control has already been eliminated. I know the prop causing fuel flow problems sounds weird, but I've had it cause stranger problems in HSGI.
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