Lkuest

I'd be interested to see some mishap statistics between the "J" and the legacy aircraft. I feel like that's the only "apples to apples" comparison that can be made since the C-130J was designed to not need an FE. It makes sense that more eyes are better, but there's been only 1 hull-loss of a US Air Force C-130J since they entered operational service, vs how many hull-losses for the E/H in the same time period? It still doesn't mean anything though unless you factor in mishaps/flight hours. For all we know, the J's might have been overdue for a mishap, and are fortunate everyone was able to walk away from this one.

You checked the coordinator potentiometer, but did you also check the 65/66 degree switches? Does the electronic fuel correction light come on and go out at the proper time during engine run? Does the light stay on statically at all throttle position? It is supposed to (looking at Speed Sensitive Control 94% switch, Coordinator, Engine Relay Box if it goes out with throttle movement). I would also check the switch in the flight deck, as well as the engine temp control relay in the cargo compartment for proper operation. After changing the TD valve, checking thermocouple wiring, and doing a TD Amp Test Set, I'm afraid you might have to troubleshoot this thing with a wiring schematic and a multimeter. You might also swap out the TD Amp for kicks just in case vibration makes it bad.

You didn't state if you did a TD Amp Test Set on it. You might check the wiring between the T-Block and the Thermocouples. Also, swap the Y-Lead leads on the T-block between the Amp and Ind sides, both green and white, and see if the problem changes. Without any other information, it sounds like a malfunctioning TD Valve to me. Let us know what you find.

Is this the same engine you've been having problems with, or is this a new problem?

You want the good stuff, you have to pay for it. We were only giving out our best "scrap", which still had about 1/2 to 1/4 life left. That's still a lot of flight hours for a "gift". They can be furious all they want, but complaining about the quality of a free hand out at a time when we can't even afford paper towels in our restrooms seems a bit petty to me. From what I understand, the U.S. even paid to put the aircraft through a major Depot inspection. Basically, we paid these other countries to take our aircraft, giving them a free capability they didn't otherwise have. If the Herc is a "scrap gift", they can always invest in an Antonov. I hear those are pretty popular around the globe.

If you've got 500 in lbs in High Speed Ground Idle, you definately need to calibrate your torque indicators. It takes much more than that just to maintain RPM within limits. Even in Low Speed, it's typically between 600-800.

Just for my clarification, does the TIT hit a wall at 850, and the electronic fuel correction light stay on above crossover? If so, it might be a bad 94% switch, which is something you cannot check with the TD Amp test set.

Let me see if I understand your situation: 1. The engine will dramatically reduce power (RPM, FF, TIT, Torque) at 850 degrees TIT or higher only. Moving the TD Switch to Null corrects the problem. 2. The TD Valve has been changed to another motor, but the problem persists on the original engine. 3. The coordinator fails the crossover check by 10 degrees high. To answer your question, the coordinator will indeed fix the high crossover temperature as long as the TD Test set verifies crossover temperature statically. In my experience, the engine actually runs between 4 and 10 degrees higher than the TD Amp setting at crossover anyway, so I like to see a TD Amp test set crossover temp of 770 or less. You can test the coordinator with a multimeter instead by disconnecting the lower cannon plug. At 60 degrees, resistance between pins A and B should be 385 +-30 Ohms. At 70 degrees, 595+-30. At 80, 800+-30. At 90, 1000 +-20. Resistance between pins A and C should always be 1000 +-20, and no variation of more than +-10 ohms between 60 and 90 degrees throttle angle. Never ohm check the coordinator potentiometer with the throttle below 60 degrees. If this check passes, but the TD Amp test set shows crossover out of limits, suspect a faulty TD Amp or dirty power going to the TD Amp. I've seen dirty power make the amp go to full take before, but it usually does it on all 4 engines due to a bad invertor or other AC Instrument and Engine Fuel control power problem. If it only happens at a certain throttle position, I would personally suspect a bad thermocouple harness. The E models are notorious for the Right Hand harness being cut into by the turbine overheat detector bracket as the engine torques within the nacelle. Even if it is not cut, I'd change both the harnesses AND the T-block for good measure. The T-Block is notorious for checking good when cold, but failing when it heats up. You could swap the TD Amp leads on the T-block with the Indicator leads as tenten suggests and see if the problem changes. If the T-block or thermocouple harnesses were bad, after the swap, you would see very high TIT during the malfunction, but no change in any other engine instruments. This is because the indicator would now be seeing what the TD Amp usually sees during the malfunction, and the Amp would be seeing the correct indication that the indicator usually sees.

With everything you've already checked, it sounds like a fuel control. You might swap a fuel control/coordinator combo real quick to verify. It's the fuel control's job to get to HSGI, and it should stay in acceleration mode if it hasn't reached the right RPM yet. Since it doesn't have an abnormally high fuel flow, the fuel control is apparently happy that it thinks it has arrived at HSGI and changed out of accelerating mode. If the valve housing was causing low RPM, the fuel control would be stuck in acceleration mode, and the result would be high torque and fuel flow as the fuel control keeps putting enough fuel to accelerate to on-speed.

I've always used the HP48, but the part number for the program cartridge isn't loaded in the US Air Force supply system. You might contact a tech rep with Rolls Royce to see what they can do for you. I hear there is a newer calculation that is supposed to be more accurate and more generous, but I haven't seen it come my way yet, so it is just rumor as far as I know. Theoretically, the more humid the air is, the less power the engine should be expected to pull, so the efficiency numbers should be higher on a humid day than what we currently calculate.

I understand exactly what you are saying about overspeed protection and LSGI, but we have an ops check that not only tells you that you have overspeed protection, but at what exact RPM it kicks in at. It was determined that the Air Force was buying LSGI buttons that were failing prematurely because the manufacturer didn't meet the specs, and the button failure was a commonly known problem at the time. This was button down, stays down, no low speed. I offered him an opportunity to salvage all of his flying events by doing the actual ops check and a resync, but he chose to be late instead. Ever after that, I saw him as an FE that didn't want to fly, and every time he hit the flightline, he lived up to that impression. We started parking in front of his airplane anticipating having to work something stupid, and were proven right time and again. If we could've tail swapped his crews over to a J, we would have. My point was, if we are forced to look at something minor, even when we say it's good, and it turns out as good as we say it is, we'll make sure the numbers reflect that. I don't like chasing numbers, but if that's all I got to use, then I'll use it. If you refuse to fly an ugly airplane, but it is serviceable, of course we'll look at it anyway, but it's on you. If you refuse to fly an ugly airplane, and it's actually bad, good on you, and keep doing what you are doing. I got a few aircrew hero stories myself, one involving a rudder boost pack that broke off it's mounts, but the maintenance hero stories are my favorite. Must be bias.

I think this was pretty shameful. We have tech data that specifically tells us how to leak check the power package for fuel problems. I think training might have a lot to do with this. I would be embarrassed if this were to happen where I work. I think the quality of the truck driver has a lot to do with this too. If there was a fuel leak write-up, and nothing was obvious, I would at least have my guys motor it, then run it for good measure. Some people think JP-8 won't catch fire if it leaks in the QEC, but I've seen minor fire damage before on a leaky fuel nozzle manifold, so I know it can happen. Maybe they SHOULD require maintainers to fly with you guys on a CNDs, both as a means of troubleshooting as well as an integrity check.

My bad for bringing up maintenance stats. My intention was more or less to show that if you want to play games with maintenance, we can play them too. We hate chasing stats, probably more than everyone else on account of how much overtime we work to make the stats prettier. One can only work so many 12's before a prop with a bit of a runny nose that our book says is good seems like a petty thing to gripe about. Again, you have the option to have us check servicing every time it flies, but if the aircrew dictate maintenance, then they can answer for it to someone with more rank than the guy turning the wrench. It's a game, but one we're willing to play. I had a flight engineer refuse to take a plane for no LSGI operation on a single engine. Nevermind you don't use it in flight, nevermind that system is on the flyable list, and nevermind an entire group of experienced 7-levels says it's ok, he still stuck to his guns and refused to fly. He mentioned something about not knowing if the fuel governor was working. Since when is LSGI an authorized ops check for the fuel governor? My answer was, even if the engine does LSGI, you won't know if the fuel governor is operating correctly unless you ops check it correctly. I even offered. I told him, we are going to change the LSGI button, the engine will ops check good, and you will take an ops late for refusing a flyable write-up. That's exactly what happened, and I made sure the pro super would annotate it as an ops late. When he came out to fly the plane, he had a bunch of fuel control schematics out to prove his point, but he failed to get ours. We know how the engine works. We don't need a flight engineer with x-weeks of engine schooling to tell us how the engine works when we have a collective 50+ years of engine maintenance experience at our disposal. I don't care when a flight engineer says he has 3000 flight hours of experience because I worked 3000 flight hours worth of engine malfunctions every 3 months, 8 years straight. I'm not too good with numbers, but I rekkin that engine experience is pretty high. Don't tell me how to fix my airplane and I won't ask my pro super to chase stats. We are never short on real work trying to get the rest of the fleet flyable again before the sun goes down or having to take a second lunch. Most of my time has been to support around-the-flagpole flying, so don't anybody think I'm being unreasonable in expecting aircrew to take a serviceable aircraft when our book says it is. I understand mission necessity, I just wish certain FE's I met did too. MFE, because aircrew need heroes too.

It's in the 1C-130H-2-61JG-10-1, S/S/SN 61-10-21, para 6 for Propeller leakage inspection. The pump housing as a whole is allowed to leak 1 drop/45 seconds either operating or statically. This does not include the propeller shaft seal, and nothing else on the prop is allowed to leak. If I get called out to an airplane for a lip seal leak, I'm going to use the maintenance book for the limit. If the aircrew refuses the plane for something that's within limits to me, it's their option, but it's also a late or an abort against OPS, not MX.

The Prop brake is physically located inside the Reduction Gearbox and is meant to hold the propeller shaft steady. Prop brakes are composed of two cone-shaped components that come together to create friction, much like the brakes in your car shaped like bowls. The brake is held in the applied position by spring tension. When the propeller rotates backwards, the cones are forced together to create a wedge effect. To release the brake, starter torque is converted to thrust through helical splines to overcome spring tension and separate the brake assembly. After a certain engine RPM is developed, oil pressure has been built up enough to overcome spring tensiton and hydraulically separate the brake assembly. The reason some brakes are stronger than others may depend on several factors such as: How much are the brake pads worn? Is there build-up on the pads that reduces friction? How old is the spring that holds the brake together? Has the brake been damaged? Because these conditions have an infinite number of combinations and levels, no 2 engines could be exactly the same.

You're on the right track. If you never set the prop brake in the first place, why would you need to release it? I'm not really sure on that one, but you never know who tried to spin the prop backwards between flights while being around the aircraft. Maybe someone on a maintenance stand was leaning on the prop blade, or maybe all the oil that lubricates the brake lining can get squeezed out from the spring tension holding the brake in the applied position. I'm assuming it's been a problem before because it's pretty much step #1 in the FI to check the prop brake if the starter shears. It CAN be set hard enough to shear a starter. We got called for a stuck prop brake, and I bent the T-bar trying to move it. That's when I wisened up and learned you are supposed to pull on the bar, not push. Also, it helps to jam the prop towards in the wrong direction to break the initial friction of the brake wedge, then it should rotate like normal. Sounds counterproductive, but it works wonders. I'm not sure if it came back shut down or not as the blades were already in ground idle.

Our T.O. actually tells us to release the prop brake by slightly bumping it. It also tells us to alternately bump the prop and inspect compressor blades for about 30 degrees of prop travel to fully inspect all the inlet compressor blades. People talk about the beta feedback shaft transfering fluid, but it is largely misunderstood. If the beta feedback shaft transfers fluid when #1 is pointed down, wouldn't that also happen during operation with centrifugal force? The beta shaft allows the barrel to vent air and excess fluid into the atmospheric sump in the pump housing. During operation, the atmospheric sump fluid is scavenged into the pressurized sump. When the prop is static, the atmospheric sump retains that fluid. If the fluid level rises above the bottom level of the front or rear lip seals, gravity puts fluid pressure against the seals. The lip seals are garloc seals, which are pretty much dust covers not designed to take fluid pressure. We leak check brand new ones at 3 psi. This is why lip seals are allowed to leak 1 drop every 45 seconds. Your mileage may vary though. I was dropped off to do a prop service check on an aircraft that had been sitting for 20 days. Two of the props had #1 pointed down the entire time, but there was no evidence of leakage. Good lip seals. I've heard of Crew Chiefs so afraid of getting an LOR for a low oil light incident, they don't even bother checking the fluid level, they just pour 2 quarts in the prop and call it a day. They don't get threatened with an LOR for overservicing the prop, so why wouldn't they? The problem is that fluid has to go somewhere. Whether the barrel gets full and vents the fluid to the atmospheric sump, or the pressurized sump becomes too full and vents excess pressure into the atmospheric, the bottom line is the fluid level is much higher than what is required to create external leakage throught the lip seals, which creates more work for the jet troops at best, or sends the aircrew to the hospital for smoke inhalation at worst. I think overservicing props on purpose to avoid stress is criminal. LOR's aren't the answer for the low oil light problem. Only proper training is. The bottom line is leaving #1 blade down causes a leak for the same reason as overservicing does, by raising the atmospheric sump fluid level above the bottom of the lip seals.

I read up on the J prop a bit, but there isn't a reason explicitly stated in the maintenance manuals as to why the propeller feathers during shutdown other than that's what the computer tells the propeller to do. You can shut down with the blades in flat pitch, but that's the exception, not the rule. There is no prop brake (may be a TCTO in the works), and the propeller is not connected to the compressor, so when the propeller rotates, it only spins the aft turbine (twin spool design). I believe the intention of parking the prop in feather is to prevent or limit rotation when the aircraft is shut down, and to wind down the propeller more quickly during shutdown. It doesn't work 100% though. I've done quite a few e-model engine runs in front of the J's and got their props to wind up a bit. I also got a kick out of driving by the J maintainers and tell them the forgot to asterisk their props. This weephole on the E/H prop is largely misunderstood. If it leaked out, you'd have to wonder where the fluid comes from, and why it doesn't all leak out from centrifugal force during prop rotation. You put #1 blade up to prevent the hollow beta feedback shaft (blade angle indication) in the #1 blade area from draining the barrel assembly into the atmospheric sump. That by itself isn't an issue because it all scavenges up during operation. The problem is, when the atmospheric sump gets a sizeable amount of fluid above a certain level just sitting there, gravity pressure pushes down on the fluid to leak out of the front and rear lip seals. The lip seals are just dust covers not designed to hold back anything more than atmospheric pressure. They are garloc seals. We leak check them at 3 psi. Your mileage may vary though. I was sent out to do a prop service check on an aircraft that was sitting still for 20 days. #1 was pointing down on 2 props, and neither had any evidence of external leakage. They had pretty good lip seals. Gizzard, I know what you mean about using the back of your hand on the Pitot tubes instead of your palms. I did that with gloves on one time, and instantly smoke poured from my glove. I was taught the backhand method before, and instantly grateful of the advice. I tried to run up to the flight deck to save the pitot tubes and I caught the FE in the way with all his bags in his hands about do come down the steps. The best excuse he could come up with for the pitots being left on was that he hadn't finished his checklist yet. I wasn't even asking for an excuse. I was just asking him to turn them off. Repeatedly. I was contemplating having to use the backhand method again, but he finally managed to put his gear down and flip the switches off.

The timeframe for when Yokota will receive J's is a moving target, and has been effected by several different issues. For one, the Pacific region doesn't have as many strict aircraft requirements as the EU does, so the J isn't necessary for flying in the airspace without a waiver or restrictions. This puts Japan at the lowest of the priority scale for upgrades to the AMC fleet. Another is all the other units that have decided they wanted to go J keep bumping Yokota down the ladder. The date has changed several times, but the current timeline puts it at maybe 2017 or 2018. It will probably change a few times between now and then, so there it's almost a waste of time counting this egg until it actually hatches.

I believe only the LC-130's require nacelle preheat, although I've heard Wyoming may have Mod'd their engines with the system. The 70GS lists a handful of MDS's with the modification, but I think it is wrong. The 16W only lists the LC's as having the preheat requirement. All Air Force C-130's have wiring for the system throughout the aircraft. I wouldn't think the system would need to be deactivated as the system, when equipped, only functions when the condition lever is aft of the RUN position AND the aircraft is on the ground, but I guess sometimes you can never be too safe for some people.

The objectives of the synchrophaser are speed stabilization, and when a master propeller is selected, it establishing phase angle relationships. It accomplishes both of those objectives by influencing RPM. By asking if the synchrophaser can cause an engine to fail to make power, I am assuming you have an RPM problem since that is what the synchrophaser is designed to change. Our tech data states that an error of 1% RPM can cause an error of efficiency of .45 to .9% efficiency. The synchrophaser can in fact cause an engine to be low power under two circumstances: Engine efficiency is very close to 95%, and RPM is greater than 100%, or the synchrophaser is causing an overspeed of greater than 103.5% under stable throttle position and the fuel control fuel governor is cutting fuel. In either case, you would be checking efficiency at an RPM other than 100%, which you must not do if you wish to ensure accuracy. Your question also makes me assume that, when checking efficiency, your efficiency is good when propeller governor is in mechanical, and it is bad when your propeller governor is in synchrophasing mode. Again, you should only check engine efficiency at 100% RPM. Just like Cheesehead has mentioned, efficiency depends on many factors, so if your engine is that close to 95% that engine RPM is weakening the engine, you may have other problems. Efficiency is a function of compressor and turbine efficiency. Turbine operating hours, damage, and thermocouple indication all affect turbine efficiency. The compressor's job is to provide the turbine with an adequate air supply. Whatever affects the air supply to the turbine can ruin the efficiency. Think high operating hours, blade damage, air leak (bleed air ducting, anti-icing, compressor case splitline/seal leakage). Also, ensure that your torque and TIT indication systems are accurate or your efficiency numbers will be inaccurate. A 200 in/lb error in torque indication will lead to a 1% error in efficiency. A 5 degree error in TIT indication will equal a 1% error in efficiency. Also, make sure your pressure altitude and outside air temperature readings are accurate.

It could be the master/slave board on the new sync (two being bad in the same way is a stretch), but I'd put my money on bad wiring. Every single time I've seen this issue, it's been wiring. It can be tricky though. The engine conduit might be bad, but disconnecting it from the prop might make it ohm check good since you are moving wiring around within the braided shielding. You either have to check it while it is still connected to the prop (ohm check from the horsecollar), or ohm check it to ground while moving the front connector around to try to get a worn wire to chafe against the wire-braid. Of course, if you just got it from depot or had major wiring repairs, you might have a crossed wire somewhere in the wing. Seen that before too.

I'm sure it's for a few things, including throttle alignment. The one thing that I CAN say that's not assumption is that the TIT indicator is required to read +-6 degrees of actual, which explains 1083 being 6 degrees above 1077. This would leave 1071 on the bottom end though. I think I read somewhere that the TD valve has to correct to within 4 degrees of desired. I can't remember where, so for all I know I just made it up. If that's right though, than that brings 1071 gauge inaccuracy down to 1067 with TD inaccuracy. Without spending lots of time researching it, that's the best I can do. 1067 + 4 (TD valve error) = 1071 + 6 (Gauge error-) = 1077 + 6 (Gauge error+) = 1083--1067-1083 range. The reason there might not be a 4 degree TD valve error on the high side might be explained by the redundant Temp Limiting setting on the amp that kicks in just above takeoff temp, so you should have 2 separate settings keeping things at 1077 or below instead of just 1 setting at 1071. If I'm off base, someone else please chime in.

With RPM, TIT, FF, and Torque all low, I would think the problem is in the engine. The propeller's job is to maintain 100% rpm, no matter how much power the engine is putting out. If the propeller were to malfunction by increasing blade angle, the FF would not change noticeably, RPM would decrease, but torque would increase. If the prop were to decrease blade angle, torque would decrease, but RPM would increase until it hit the fuel control fuel governor where fuel flow would finally drop, but RPM would remain high. The problem would have to be in the engine fuel system. It sounds as if the TD System being turned on and off creates a difference, and the engine behaves normally in null, drops off power in auto. I would suspect a bad coordinator or bad wiring in the TD system. You might slowly swap TD system components between engines until the problem moves over to the other engine. I know it sounds silly, but with a strange problem like this, you'd be throwing money at it just changing parts. It may not make sense for a fuel system component to reduce RPM, since that is the propeller's job, but it may be taking so much fuel that the propeller drops down to 25 degrees blade angle and cannot maintain the RPM for the power anymore. Without running the aircraft myself, this is all that makes sense to me with the information provided. The problem cannot be caused by an air leak because the drop in torque would be accompanied by an increase in TIT.

What is torque doing under all these conditions? Also, have you performed a TD system check using a test set?