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

hehe

Members
  • Posts

    232
  • Joined

  • Last visited

  • Days Won

    8

Everything posted by hehe

  1. Have you checked the PPDU/LVPS circuit breakers?
  2. You still have the briefing available to show? Is it the one that floated because the tanks were empty and it floated like 50 hours before being sunk
  3. First thing would be to make sure it passes a cabin decay check. Not by a second or two but a good pass. The ability of the cabin the hold a pressure is important Next I would check the Jet Pump and check valve under desk in aft right of cockpit. Check for cleanliness and corrosion. Both have been known issues Check outflow, safety valves. Make sure the outside static ports on right side of forward fuselage arent clogged or painted over. Those are the sensing ports for pack and safety valve
  4. First question is what year/model? Yes it matters if its a B-model verse a mid 80s H-model. Ground test valve commonly considered bad for transfers and to be honest it almost never is. Check the rigging to the ground test valve. It should be tighter on one cable verse the other so that the valve wants to pull to the closed position. The incorrect rigging of the cable is much more common than a valve itself. Check the brake shuttle valves. These can transfer aux to utility and utility to aux when brakes are used. They should not allow fluid to flow through them once they shift to other side of shuttle. A strange one that I have seen is one of the brake selector valves not receiving power to close so both valves were open and causing util/aux brake pressure to fight at the shuttle valves. Its easy to check. They are powered close so when energency is selected, you should have 28 vdc on normal selector and opposited when normal is selected. Nose landing gear uplock, NLG actuator and nose gear emergency selector valve can also cause this. Not too common but I have seen it. Do you have UARRSI, refuel pods or weapons systems? If so, all of those can be points of transfer. Emergency brake and normal brake accumulators should be checked for internal leakage as well. Most common of all is a person not fully depleting brake pressure on BOTH normal/emergency before moving the ground test. There is always some avionics or electrics guy that wants to help but doesnt know the details of running hydraulics. I have seen people chase this ghost and come to find out the new guy was improperly trained on tying ground test.
  5. I have a library full of C-130 books, odds are I have the book. Was it hard/soft back? , kind of a small/thin book or large/thick book? Color images/black-white? Describe it the best you can to help me limit my search. I have too many books to just go page by page
  6. The Ejected pressure from the engine should never indicate exactly in the flight deck for quite a few reasons. 1. Pressure drops across distance. In order to get 125 psi in the flight deck, the engine would need to be making 150-ish psi at the engine (just an estimate). Pressure drops across distance because flow and volume is required to get that pressure across a distance. 2. The system has allowable and normal leaks. Every valve in the system is bleeding off or leaking a small amount. Some are calibrated to leak a certain amount and others just leak as a result of their design. Very few pneumatic systems are perfectly leak proof. For example, if you have 20 valves in a system and they are all leaking small amounts of air, your 125 psi becomes more like 70 after the bleed offs. This is why the system has a bleed down time. The drop from 30 to 15 psi in 22 seconds or more is a indication a satisfactory level of "normal" leakage. If there were no leaks in the system at all, your bleed air pressure would never drop. 3. Almost all systems are like this. Hydraulics, fuel, electrical, oxygen, etc. The system is designed to provide a higher amount than is required so that it can "bleed off" some for normal system losses and still provide a set amount. Hope that helps.
  7. Here is a C-130 flight manual for reference. This sequence started on A models because the GTC door had to be manually closed and the engine generators were split between inboard/outboard. So they would start #3 and #4 and then shut down GTC, manually close the door and then start left wing. Some pubs mention starting engines in a different sequence than 3/4/2/1 to spread the wear and tear on engine starters. The first engine started off of GTC/APU Bleed air will wear faster than the others with engine bleed air because of the higher flow/pressure from the engines. Generally speaking, if you 100% always start #3 first, data/trends say that you will replace the #3 engine starter before the other engines.
  8. It is in the Aircrew's starting engines checklist of the flight manual. It says something like "normal starting sequence is 3 / 4 / 2 / 1" depending on which flight manual you read
  9. 1. I will have to double check but I think the 3k RPM is low speed ground idle and 3.6K RPM is normal ground idle (engine at 100% rpm) Why would you ever need to figure out the GPM at low speed ground idle? You would never fly at that engine RPM 2. Pressure equals out. If you had 3K and 3.1K you would probably see a little bit above 3K by the time the pressure equalized and got to the pressure transmitter at the utility or booster panels. Pressure drop is roughly 100 psi every 50 feet (not written down anywhere just what I have seen)
  10. Check the simple things Util reservoir filters (pressure return/case drains and reservoir vemt filter). Something as simple as a wet vent filter can cause enough of a liquid lock that pump would cavitate during large draw such as landing gear movement. Swap the low pressure switch to booster side. See if it follows the switch to booster side. Check the landing gear flow regulators. Should be free flow toward motor and regulated away on both up/down lines. What was the util system pressure drop? Did it drop below or around 1300 psi?
  11. Is this the same aircraft that was having these issues? There was a post about a week ago with similar issues Previous history of this? Any recent maintenance done? I wouldn't automatically call it bad if it just flickered. It could be a loose cannon plug on the low press switch and the gear going up shook the wall. It could just be a loose push to test on the warning light. What has been done to resolve?
  12. The 1c-130A-6 references you to the 11A18-14-7
  13. Do you use the 1c-130a-6 for your scheduled maintenance?
  14. I just read that again and noticed you said in flight. Normally I would suspect engine pump or filters in the return system but since you are only having right side issues I would suspect mechanical issues that are only showing themselves in flight. Have you done free fall checks of that gear? Have you checked lubrication of MLG tracks, door linkage rigging, shoe rigging, ball screw/nut condition/wear, etc? Are you sure the gear is not mechanically binding in a way that is only showing itself in flight?
  15. When you say it is not passing timing checks in UTIL, what are you using as the source? Ground powered hydraulic test stand? The aux pump is very weak for flow so if you are passing timing checks with the aux pump, I would take a good look at your hydraulic test stand. What is the UTIL system pressure dropping to during gear travel?
  16. Filling the accumulator doesn't honestly do much to prevent an air bubble. It's the removing of the hydraulic line to the accumulator that create the issue No matter how fast you are in getting it capped, you will induce a large volume of air into the lines. I was a hydraulic tech on C-130E/H/J for 13 years. When you think you have the system bled enough, do another 10 cycles.
  17. Yea if you just changed the accumulator, I almost guarantee that a huge air bubble went through the system. The landing gear is a huge draw on the system and that is usually when you will see trapped air go through the system like that.
  18. Lots of things are possible. I mainly said to check the suction boost pump because you said the light came on. Usually engine pumps will just cause low pressure overall and maybe a low pressure light for that engine driven pump but the suction boost pump light coming on says the supply to both engine pumps was low. It could have been something as simple as an air bubble making its way through the system when the gear operated. Keep an eye out for having to service air side of accumulators often. If the air charge depletes often, it could be depleting into the hydraulic side and creating air pockets in the system. Were there any hydraulic compnent changes or hydraulic maintenance that happened before this flight? Have you bench checked the engine driven pumps?
  19. Yea the system isnt designed to prevent a skid at 10 knots. This might be a pilot training issue more than a system issue
  20. Do gear meet timing checks on ground? If so, Suction boost pump would be my first part to R2 If the accumulator is bad you should find hydraulic fluid in the air side
  21. The system should technically skid at 10 knots. The transducers dont have enough current until 15 knots to signal to anti-skid control box. Does it do it above 15 knots? You might be chasing a ghost here
  22. All 4 skidded or just released pressure? I would change the anti-skid control box. The entire left and right sides are separated other than the box
  23. Do your books states that anti-skid in inop below 15 knots? I havent messed with a mark 2 in probably 12 years. Which side is releasing? All brakes? Left or right? If its only one side, i would swap wheel speed transducers left to right and see if it follows.
  24. Verify that your flow regulators are regulated flow away from the motor on both extend and retract side. I would probably lean toward changing the flow regulators or bench checking them (if you have that capability. You could always swap a suspect part from left to right gear to verify. Any time you have timing issues, you would want to eliminate any type of leaks in the system.
×
×
  • Create New...