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Lkuest

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Everything posted by Lkuest

  1. That's a new one on me. If the pulse generator circuit was bad on #2 propeller, it would make the #1,3,4 prop RPMs drop from 100% to 0% (can only follow 2 %). When you switch master to #3, #2 prop RPM only should rise, thinking it is trying to increase from 0%. Since both masters are dropping, and the outboards are not, I think the problem is wiring. This is assuming all other propeller checks are good (throttle anticipation w/in 5 seconds, and no RPM difference between mechanical and normal, pitchlock check). I suggest verifying all propellers are set to a Mechanical RPM of 100%, +-0.2%, then perform a reindex and try again. If the problem persists, I believe the problem is between the essential DC bus, the master select switch, and the synchrophaser. If the master select switch is shorted internally so that a master is always selected, it will cause a problem such as this. If the propellers do not pitchlock, you may have a problem with the Essential A/C bus voltage going to the synchrophaser. The A/C power is used as a reference signal, and further amplified once error signals are given to the synchrophaser to decide how far to make the speed bias servo motor move. If the A/C power is dirty, the synchrophaser will do crazy things.
  2. Does it only do this in the flight range of power, or all the time? In Mech Gov or Normal Gov? Synchrophasing on or off? When RPM goes up, then down, what do the other indicators do? The same direction, or opposite? The best possibility is both Tach Gen spline holes are worn excessively. At worst, your reduction gearbox tach generator drive gears might be worn out. Both Tach Gen pads are geared into the same idler gear, so possibly the idler gear bearings are wearing out, or even the Hydraulic Pump gear bearings too, as it drives the idler gear. If you have a vibration signature program, I suggest doing a vibration signature readout of the gearbox to check the bearings for wear. Another possibility might be wiring near the Reduction Gearbox causing intermittent contact as the engine torques within the QEC at power. I would also swap RPM indicators with another engine, because swapping indicators doesn't cost anything.
  3. You might be on to something there. The 1C-130J-01 makes reference to the -185L(A) pn 3800599-1, which cross-references nicely with the 1C-130H-2-49GS-00-1 APU installed in the AFSOC birds.
  4. The GTCP85-185L is the APU used on the AFSOC U/W-model gunships, and the Talon-II. It weighs about 40 pounds more than the standard APU, and some operating limitations are different. Also, it has an electronic 3-speed switch. The 49GS has more info, and the limits are in the typical 49JG.
  5. The way I phrased my reply was a roundabout way of making the exact points you just made. I am aware of the Talon I with an APU, as well as why it's the only one. You try to fix the problem permanently and you keep hitting brick walls, whether you're trying to get the system to work as advertised, or simply upgrading to a new APU, which won't happen due to the extreme modifications required to both wheel well fairings. The bottom line is you just can't expect a GTC to work as advertised. I agree that it is supposed to work without a boost pump, but if it flames out when a small amount of dirt gets on the filter, it is simply just poorly designed from the start. If an item isn't even slightly over-engineered for its use, then it's intentionally designed to be repaired regularly. I can't tell you how many GTC's I've found without a filter installed because the flight engineers kept pressing the issue and refused to address the fact that there's a serious flaw in the design. Maintainers can't fix that with a filter change, only system design engineers can. Lockheed can write whatever they want on the sales brochure, but if it is physically incapable of running without a boost pump, then you're right, it's no longer a self-contained airframe. It is what it is. I don't feel the need to notify Lockheed of their issue. If they haven't heard enough about the GTC over the last few decades to consider it's inadequacies, then someone's asleep at the wheel. Either that or just wanting to sell the newest model. I can't imagine why anyone would try to defend a machine such as the GTC with a reliability so abysmal it's almost legendary, if not plainly laughable. As for the problem at hand from the original post, I felt I put enough in my post to suggest parts to change to give it the benefit of the doubt, as well as to set the expectations low enough to explain why changing those parts may not fix the problem in the long-run. If it does, great. If not, it is what it is. Change a GTC or three and it still may not fix the problem. I think that experience speaks for itself.
  6. Change the GTC to an APU and you won't have this problem. Just a little story to illustrate my point, the GTC on 9812 refused to run without a boost pump since the 90's. The story I got was they were so tired of the problem getting written up that they added it to the PDM contract to investigate the issue. They did a flow test from the fuel source to the GTC and couldn't find the problem, even changing the fuel line itself all the way down to the GTC, and it still didn't fix the boost pump issue. They ended up just leaving the write-up in the info page of the forms. More recently, the leadership got tired of seeing it there, so they created a tiger team to fix the problem, reaccomplishing a lot of the work that has been done over the years, with no result. I personally changed 4 GTCs in that plane for various reasons, and we still could not find one that would run without a boost pump. The maintenance tech data states that you may need a boost pump to run the GTC, but for some reason, it never made it into the flight manual, even though the mountain of evidence shows the system design is inadequate to run without a boost pump. Air crew can press the issue all they want, but the end result will be unsavory maintainers just pulling the filter out to make them happy. If you truly want it fixed, change over to an APU and be done with it. Otherwise, just use the boost pump, and count your blessings when you can actually do a self-contained start. Sometimes, we have luck changing the filter, strainer screen, atomizer, and fuel cluster to fix this problem, but I don't think anyone will be able to get 100% of GTCs to run without a boost pump.
  7. With the Series III engines and below, the Air Force took all the odd-number designations, and the Navy took the evens. From my experience, the -15 fuel control NSN cross-references with the -14 engine, not the -16. I have seen some websites that show the -16 has an HP rating of 4910 SHP vs 4591 SHP for the -15 listed on other websites, but never the same website listing both -15 and -16 numbers. I've seen SHP ratings for the same engine be different depending on the website I was looking at at the time, so it doesn't mean much. Just the fact that the fuel controls are different may suggest a difference in fuel control tuning.
  8. Lkuest

    AMARG

    90-0161 was listed as crashed/ w/o in 2002 near Puerto Rico. 161 was lost in PR I wonder if they stored parts of it in AMARG as they have done in the past as with 63-7854 or if it was a typo? Here is the post. MC-130H 90000161 12/11/02 27 It has never shown on the inventory before but the post shows a date of arrival of 2002. 63-7854 was also in Area 27. Bob
  9. It is pretty impressive to see this kind of damage on the filter without the engine dumping oil overboard or venting internally. If this is caused by oil pressure, it is because the pressure going in is significantly more than the pressure coming out. There is a built-in bypass for this, so perhaps your bypass is ineffective or clogged, and someone "staked" the button to prevent it from indicating bypass. It would be best to wait for you to perform the scavenge backpressure test. Lockheed considers a pressure differential of 3-8 psi to be normal between the oil pressure going in and that coming out. The only other idea I have is to just blindly change the filter assemblies, to include the heads and bowls in order to eliminate all possibilities. You could also measure the length of the spring on the bottom of the filter and compare it to one that is not malfunctioning. Since it is happening to more than one engine, perhaps it is an error in installation, perhaps the cork gasket being installed incorrectly, or double-stacked.
  10. I'm definitely no expert on converting engines, but I'm pretty sure just about everything aft of the Diffuser, including the Y-Lead, is a different part number, with the exception of the Rear Bearing Support casing, Rear Bearing Assembly, Tailpipe, and T-Block. The fuel control will require replacement due to the different tuning internally for the extra fuel flow, but the TD Amp can just be re-adjusted to the new limitations. -7 to -15 conversions aren't too common because it is much easier to overhaul and re-use components than it is to order all new parts, but the US Coast Guard accomplished a set many years ago. See Lockheed Service News Bullitin Volume 26 No 1. The gist I got from it was the easiest way to do it is order a conversion kit directly from Rolls Royce tailored to your situation (some -7 engines may require a Gearbox or Compressor modification.)
  11. Install a micrometer so the measurement end of the tool is as far aft on the propeller shaft as you can get it. Put 81kg of downward and upward force on the end of the prop shaft. The micrometer should not move any more than .005" down, or .015" up. It must be overhauled if the limits are exceeded.
  12. Lockheed Service News Bulletin V8N4 has more information on this issue, but you're right, just because it is flickering only during crossfeeding, it doesn't mean there's nothing wrong.
  13. I agree with NATOPS completely. Usually, you have Fuel Flow and the Parallel valve at 16%, but you never really build up the 120PSI of pressure until about 35% RPM or so, and no two engines have the light come on at exactly the same time. Since the light is coming on immediately at 16%, I would suspect either total blockage on the outlet of the primary pump (or the pump itself), or an extremely weak pressure switch that is actuating at a very low PSI. Under such a condition, the Tank boost pump, the Centrifugal boost pump, and the Secondary pump all together would put out positive pressure, even if the primary pump is working correctly. Additionally, if the Parallel valve is not installed and torqued exactly correctly, the valve could stick in the actuated position. I'd be curious how your maintenance checked the pump without using a dedicated test stand or swapping out for another pump.
  14. I think this is his best bet, unless they to buy surplus Middle-Eastern C-130H's as they upgrade to the C-130J. http://www.amarcexperience.com/ui/index.php?option=com_content&view=article&id=4&Itemid=167#q7
  15. The inlets for the air coming off the diffuser are on the aft side of the diffuser struts, immediately adjacent to the fuel nozzles. With air trying to travel to an area of high pressure to an area of low pressure, you essentially have three vacuum cleaners trying to suck the fuel off the fuel nozzles. This is almost guaranteed if the fuel nozzle neck is cracked. Typically there is too much airflow to allow the flow of fuel orifice to go sideways, but it is possible because of the proximity of the bleed air inlet points on the diffuser struts, especially in LSGI where the open 5th and 10th bleed valves increase the turbulence and decreases the air velocity within the diffuser, and the secondary orifice is receiving less pressure than normal, disrupting the spray pattern. I hesitate to say it is fuel nozzles though. If you have jet fuel vapors coming out of the A/C ducts, it will be very obvious it is jet fuel and not hydro or oil. There will be no doubt. If it doesn't smell like fuel, don't pull the fuel nozzles.
  16. There are two fundamental causes, the engine is losing power, or the propeller is demanding too much power (uncontrollable blade angle increase). You isolate which one by watching torque. The moment the the RPM begins to drop, does torque increase or decrease? If torque increases with an RPM decrease, then the propeller is demanding more torque than the engine can put out at that throttle setting, and the engine will die. If torque is dropping as RPM begins to drop, then the engine is putting out less torque than is required to support 25 degrees of propeller blade angle. If you find the propeller is causing it, begin to look at things that can cause a blade angle increase, such as rigging, valve housing internal linkage interference, NTS linkage bad, torque retaining lug loose, valve housing failure. If you find the engine is causing it, look for causes that either rob the engine of fuel or lots of air, such as the acceleration bleed air system, blown bleed air duct between check valve and diffuser, kinked fuel lines, clogged fuel system components, fuel control failure, etc. Anything that can affect the efficiency of the engine, such as turbine or compressor damage can also cause these issues. You may also have a malfunction related to the Temp Datum system. If TIT shoots up as the RPM drops, you very likely are losing a massive amount of air. If TIT is dropping as RPM drops, you are likely losing fuel. There really are many causes for this malfunction, so without more information, it is hard to get more specific than that. You must do a full performance run, operationally checking out every aspect of engine and propeller performance, then look at all the engine instrumentation at the time of the malfunction to determine the cause. Little things like the secondary fuel pump pressure light coming on, or the low fuel pressure light illuminating could be important pieces of the puzzle with this one.
  17. Can you give us more information about what the engine instruments are doing, before and after rollback? Torque TIT Fuel Flow RPM Without more information, I would suspect the valve housing is biting too much air in the flight range, causing RPM to drop and the fuel control to go into acceleration mode, making TIT shoot up. Changing the Valvehousing is my shoot-from-the-hip recommendation. Please let us know what you find. *Edit* Might want to check the NTS gap too.
  18. I would be interested to figure out which two wires it was. It might explain the strangeness of the flameout timing, as well as why there wasn't another discrepancy associated with the wiring problem.
  19. We have tech data on C-130's for use of Animal Protein agent. I'm not sure if that's what Purple K is, but we are required to clean every square inch within the QEC if the agent gets discharged in there. Halon has no cleanup requirements. If we go backwards, someone needs to be slapped.
  20. Coming from AETC, I expected there to at least be a quadrant cover over the sticks.
  21. I did some googling. http://www.flightglobal.com/airspace/media/civilaviation1949-2006cutaways/images/8835/lockheed-l-400-cutaway.jpg
  22. I just found who to give the "Worst Advice" award. I would recommend if you are going to provide tech support, you should make sure you read the problem first. The limit for the fuel control is 70 degrees lean, or 70 degrees cooler in null than in Auto. What's the unit of measure? TIT. Temperature is not the problem as he is hitting 1083 easily, therefore, fuel is not the problem. Changing the fuel control would be a waste of time. Efficiency is a comparison of TIT vs. Torque only. Checking static blade angles is a good idea, but only if you are checking the accuracy of the Torque Cal. When you check efficiency, the flyweights control blade angle. If you are at 100% RPM at power, the prop cannot cause efficiency problems. If your TIT is high and your Torque and Fuel Flow is low think Air Leak or indication. Anti-ice is a good idea, measuring torque calibration also a great idea (Calibrate in LSGI, not HSGI!!), but think anything that runs off of air. Especially on a low power new engine, I would highly suspect an air leak. Air equals power, but it also equals cooling. Air loss makes your TIT higher than your fuel flow allows it to be (isn't that really what you're seeing?). Don't think prop brake. Your starter releases it as soon as you rotate. If it was engaged, you should see a slow start. When the starter is not engaged, oil pressure hydraulically disengages it anywhere north of 28% or so RPM. If it were to somehow stay engaged, you would have brass particles all over your gearbox mag plug sump areas and External Scavenge Oil Filter. Think about what would happen if you decided to drive your car with one foot on the brake the whole time. You'd run out of brakes very quickly due to overheating and material loss. Let's go over the small list of things that could cause a low power: Indication (RPM, TIT, Torque, wiring, T-couple harnesses/T-block/Y-lead) Accurate RPM too high (Indicator also low, showing 100% when really 102%) Torque Cal (must move throttle to lowest torque setting before calibrating. Incorrect calibration will indicate lower max torque) Outside Air Temperature or Pressure inaccurate Air Leak (from any part that uses engine air) Torque not measured at max TIT/Torque (or 1050, whatever your formula requires) On a side note, it is normal for new engines to lose more torque during air conditioning operation than the other motors on aircraft that do not have bleed air regulator valves. If your aircraft does, maybe the bleed air regulator valves are out of calibration. In my world, efficiency is checked with Bleeds Closed, Hydro and Generator off. We can check it the same way the aircrew do, but only to troubleshoot a low power caused by anything outside of the engine itself. Also, if crossover temperature is within limits, I don't care about the bump. There is no tech data that tells you to look for that bump, only a temperature range it must be in at 65 degrees TLA. Crossover is only for throttle alignment. If you already have throttle alignment, why would you expect the engine to correct even more for throttle alignment? A more accurate check of TD system function is a TD system ops check.
  23. I wonder how many furlough days it would take to pay for all that equipment.
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