ddhix replied to HispanicMechanic's topic in C-130 TechnicalI second this.
Low TIT, High Torque, High Fuel Flow
ddhix posted a topic in C-130 TechnicalHad 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.
TD AMP / TD VALVE ?
ddhix replied to tenten's topic in C-130 TechnicalThe answer has already been given, but I just wanted to add a tid-bit of followup information for the original poster since he seems fairly new to mysterious engine troubleshooting: Typically, when I respond to a red-ball for a hot start, I do the following events (a few alterations if necessary): #1 Of course, shut down the affected motor, #3 engine, for example. #2 Have them start it in Null. If you get a normal start, then your Hydro-Mechanical (TD Valve) is functioning properly, since NULL takes away the engine temperature computer (TD AMP!). If it STILL hot starts, then swap TIT Gauges with another engine's TIT gauge (so, #3 gauge is suspected bad, swap it with #4 gauge). Usually at this point, I will have them shut down another motor so I can swap gauges. Start the suspected motor (I do this in Auto, I want to see it again): If it starts fine, then obviously you will start #4, and you'll probably see a hot start. This usually only happens with Cold Starts, as usually gauges like to LOSE indication instead of GAIN indication. If it hot starts in Auto, and Null, you probably have a TD Valve or Fuel Control Bellows issue, but do not ignore your TD Amp, as it could be sending bad signals, etc. If it hot starts only in Auto, you most definitely have a wiring, or TD Amp problem; I like to shake wires as much as possible when testing the TD Amp. Also, testing the TD Amp does not show the problem every time. Someone here said the 130 will make a liar out of you; it's true. A lot of times, if I find no other problem, still get a hot start, and the Y-Box (TD AMP Test Set) says it's fine: I'll change the TD Amp anyway, and on several occasions it has fixed it. If you do restarts, and it doesn't hot start again, then I'll note the wind outside, as well as keeping detailed note in the log book in expectation for it coming back; in which case I will a TD Amp more likely. This is covered in better, more accurate detail in the 1c-130H-2-70FI-00-1-1. Block 985 if I remember correctly.
Hey guys, Just wanted to give an update. We Y-Boxed the TD Amp, it checked good. We payed a lot of attention to the Start Limiting, messed with all the wires while doing every check; nothing flipped out. We changed the TD Amp anyway. We also changed the J3 cable connecting the Amp and the TD Valve (just in case). Ran it; problem seems to have gone away. Last time we changed parts for this problem, it stayed gone for 14 days; so we will see. Everything seems good though. I really appreciate all of ya'lls help. Ya'll are lifesavers. -Hicks
Hey guys, thanks for all the information! I'll definitely be checking out the wiring harness the next time around. Anyone think the geneva loc could have a say in it at all? I forgot to mention (or just plain screwed it up in the first post), but it is typically only happening in Low Speed Ground Idle; so technically the engine is doing what it is supposed to be doing below 65% with the igniters and starting; so it is catching itself during a malfunction. I was thinking that the wiring harness could be intermittently FUBAR, actuating the geneva loc only partially (?), sending it below 65%, firing igniters and catching itself, then returning to normal; but then why is it only happening in Low Speed Ground Idle? As far as I know, though, the Left Hand Distribution box contains wires for both the geneva loc, and LSGI solenoid, too. Thank you again for all the input; ya'll are extremely helpful. -Hicks
Uncommanded Engine Shutdown
ddhix posted a topic in C-130 Technical30 March: Just had a problem with an engine shutting down uncommanded during taxi. This is not the first time this has happened. The crew took it this time because they started back up and it was fine; this engine is a problem child. If we could get some help on this we would all very greatly appreciate it. If any more info is needed just let me know. Thanks a lot! Here is some history on it: 25 Feb: #4 Secondary Fuel Pump Pressure Light Illuminated. Changed the Secondary Fuel Pump Pressure Switch, it taxied out and came right back with the same problem. We changed the switch again, along with the paralelling valve and high pressure fuel filter. Ops check good. 01 March: #4 Secondary Fuel Pump Pressure Light Illuminated. Crew said they were down sped for a few minutes, until the FE looked up and saw the light was on. He heard ignitors in the head set, said that TIT was rising with Fuel Flow. He went to pull the Ignition Control C/B and everything went back to normal. They flew 2 or 3 more stops with no problems. We could not duplicate it. We changed the Speed Sensitive Control anyway. Ran to power, couldn't find anything. This was different from the one on 25 Feb because they never had a light problem at power. 02 March: Crew heard ignitors & saw #4 Secondary Fuel Pump Pressure Light illuminated, and RPM rolled back. It Immediately "caught" itself and came back online to 100% RPM. They were low sped for about 5 minutes before all this happened. No cargo or flight deck packs were on and there was no tail wind. We ran it; could not duplicate it. Fuel Control is 80Deg Rich 11 March: #4 Uncommanded Shutdown, changed the Fuel Heater Strainer filter, checked the inlet to FHS, borescoped the engine (checked good), checked the fuel line from the firewall, checked 5th & 10th stage bleed air pucks, beeped the mag plugs, ran it, could not duplicate the issue. Replaced the Speed Sensitive Valve and Low Pressure Fuel Filter. Ran it again, could not duplicate the issue.