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Lucky13

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Everything posted by Lucky13

  1. Yes Pin C, Mixed Audio on the Pilots (side shelf), the Copilots and Flight Instructors interphone boxes all have noise on them.
  2. I can't speak with certainty about this specific brake issue, but I can say that the shift in aircraft hydraulics is towards higher PSI systems because they can create the same amount of force with smaller (therefore lighter) actuators. I worked in the development dept at Moog on the primary flight control actuators for the new Boeing 787 which uses all 5000 psi actuators for this reason. The Dreamliner is touted as the most efficient airliner to date because it's designed from the ground up to be as light as possible.
  3. Soemthing interesting we found was that when the shielding on the wire to PIN C is UNgrounded the noise goes away. When the shield is grounded again the tone is back. Same thing when we just attached a spare length of wire with a pin on it to the cannon plug in pin C. When the shielding is grounded to any location on either end of the wire the loud noise is present, when you remove the shield ground, it's quiet.
  4. Sorry for taking so long to post an update. We have traced the source of the noise to J401 PIN C on the bad interphone boxes. This is where the mixed audio comes in from the monitor panel. There is also a wire coming from the recent LAIRCM mod that splices into this wire between the monitor panel and the interphone box. We have also found the annoying loud tone (same 3 boxes, pilot, co and FE) on 3 other tails that were recently moded with LAIRCM. We are trying to research the root of the problem now.
  5. Nope, no cords are plugged in to anything.
  6. We did exactly this already. Ran the APU the interphone was clear as a bell. Tie the AC buses and the noise reapeared, altho not quite as loud as when we were running off external power. So it appears the noise is only present when running of external power or off engine power. Running off APU or battery it's fine.
  7. We had a discussion about the 18 vs 25 isssue as well. The wiring diagram that matches the tail number and fits the wires on the plane is labeled AIC-18, however all the interphone boxes say AIC-25 on the back. Maybe the old 18 boxes are compatible with the wiring for the 25s so they just changed the boxes? We were planning to take a look at how noisy the DC current powering the boxes was but we got kicked off for an engine run, maybe tmw...
  8. We have a interphone problem that's been kicking our ass trying to track down so I figured I'd post here and see if anyone has any ideas we haven't tried. The Issue... We have a C-130 H2, Tail 87-9281 with a loud buzzing tone that is heard only in the Pilots, Copilots and Flight Intstructors stations. All other stations sound clear. The tone is heard regardless of which radios/nav systems are selected on the control box and volume panels. The tone in the bad stations goes away only when you press that call button, and only on the station which the call button is pressed. Troubleshooting... We have already pulled and swapped all the boxes and comm cords, doesn't look like an interphone control box or volume box. The tone is still heard even with one known good box plugged into the pilots station, all other stations unplugged. We suspected a bad ground so we checked the grounds and audio commons to every station and they checked fine. We also ohmed out the audio lines and didnt' find any shorts. We suspect noise coming from another system so we pulled every single circuit breaker to see if one made the noise stop, nothing made it go away. We pulled wires from every terminal on the interphone junction box one banded group at a time. No Effect. We suspected noise coming from the TRs so we pulled the breakers for them and ran off battery power. As long as AC power is applied ot the plane the noise persists. The ONLY thing other than the call button that makes the noise go away is running the interphone off battery power with no AC power applied to the plane. ??????? We are running out of ideas. Can anyone here think of anything?
  9. At the recent CNS/ATM Conference I saw some really nice yoke mounted GPS units that the manufacturer had on display. I've never seen one in use on an aircraft though. Eventually they will replace all the the paper charts.
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