kersey9502

Yes!!!! a bad servo can cause this. If Yaw Damp will not engage you need to look at the rudder servo..

Try seperating the audio common wiring going into the comm boxes. This line is what all of your audio is traveling on. There should be a break at FS245 to separate the flight deck from the cargo compartment. The easy way to resolve this issue is to just diconnect one box at a time from the IJB. Depending on what Mod has been performed, If they tied into this audio common wire you could see some resistance to ground on the wire.

TinyClark, I work out of Robins. I could really use a troubleshooting diagram for the ARC-190. Thanks!!

Why I'm am saying in the air or on the ground, AP105 autopilot on the ground when engaged will drift to the left. It will not do this in flight due to the air flow over the aileron. That is a write up i have seen with that system, if it is AYW-1 autopilot that will be a problem.

What type of autopilot system are we dealing with? What is the year model of the aircraft? And is this on the ground or in the air?

A rule of thumb to remember is increase your airspeed by 2% per thousand feet of altitude. So at 200 knots for every thousand feet add 4 knots. TAS and IAS are not going to read the same. It doesn't seem like you have a problem. You can take a bag of ice and put on the TAS probe because the temperature will affect the reading also. Hope this helps!!

It could very well be linked to the ground stop circuit of number three. The question to be revealed is what is actually going on a 50-55% on number 4. Sometimes you will not get paralell until around that time. If the wires are shorted from that circuit to the ground stop circuit of number three, it could possibly happen. As far as number three and number four going through a common place such as terminal board or cannon plug is not likely. checking all the prints i dont see where they are in a common area except wire bundels. It will very interesting to see what other symptoms are going to surface when paying more close attention to the indications of that number four engine.

What are all your engine indications reading at the time of shutdown? Is number three shutting down at the same time every time? And also, has number 4 reached parallel or has the secondary pump light illuminated yet?

Yes the GCU does determine what type of generator it has online according to the PMG that it receives from the generator. Each GCU monitors (PMG) input from the main generator to determine the type of regulation to provide. If the PMG voltage is 30 VDC, the generator is a Bendix unit and the regulator for the Bendix generator PMG is selected. If the PMG voltage is 108 VAC, the generator is a Leland unit and the regulator for this type PMG is selected. One thing to keep in mind is that If the GCU selects the Bendix generator when in fact a Leland generator is installed, high PMG voltage will be established on the GCU’s PMG line. However, an internal protective (fail-safe) circuit limits the PMG DC voltage to 70 volts, When the high voltage is detected, the field relay and line contactor control relay open, which isolates the GCU from the generator system. This fail-safe system is independent of the microprocessor, and will automatically reset if the internal logic reverts to a correct generator selection. …….That’s why with the GCU’s it is usually better to troubleshoot this system by the GCU fault tree. This problem might be related to another system fault causing it to revert to a lower system excitation voltage.

Alright, first there are some things that really helps to know before T/S these problems. What year a/C and has the A/C gone under any heavy maintenance such as depot, ISO, or center wing box replacement. I'm taking it you are checking the excitation (F) coming from the GCU at the terminal board. I'm taking it is a typo saying that on number three is 96VAC and four is 50VDC. something is drawing the voltage almost in half. have you check the horse collar cannon plugs for any bent pins and pushed back pins. When you turn on the generator and you get the out light what is the fault message on the GCU? This sometimes leaeds you in a different direction. this could be a fault protection of the GCU to limit the excitation under a faulty condition. I guess all I need is what fault message and the year of aircraft..

What is this transmitter for?

The TCTO that was for the modification for the isolated DC circuitry was 1C-130-941. The result of this modification will alert aircrew of this condition so that battery power conservation measures may be initiated to limit power usage to essential requirements. As far I know this TCTO should not have affected the press to test function. All the lights are jumpered together for the press to test. Where is this aircraft from? When the Battery is turned on, the Isolated bus is always powered. This is what bus the lights are powered off of.

1C-130-1829 was the Electrical System Upgrade (ESU)

TCTO 1C-130-1822 was for the installation of GCU's and solid state inverters on select aircraft.

These Aircraft were modified with TCTO 1822 and 1824 C-130E: AF62-1784, AF62-1786 through AF62-1788, AF62-1793, AF62-1804, AF62-1817, AF62-1820, AF62-1824, AF62-1833, AF62-1842, AF62-1855, AF62-1856, AF62-1858, AF62-1859, AF62-1864, AF63-7781, AF63-7792, AF63-7800, AF63-7808, AF63-7809, AF63-7811, AF63-7812, AF63-7814, AF63-7817, AF63-7818, AF63-7824, AF63-7825, AF63-7839, AF63-7847, AF63-7851, AF63-7857 through AF63-7859, AF63-7868, AF63-7872, AF63-7877, AF63-7883, AF63-7884, AF63-7885, AF63-7887, AF63-7889, AF63-7895, AF63-7898, AF63-9815, AF64-0495, AF64-0498, AF64-0499, AF64-0502, AF64-0504, AF64-0510, AF64-0512, AF64-0515, AF64-0517, AF64-0518, AF64-0520, AF64-0521, AF64-0525, AF64-0527, AF64-0529, AF64-0531, AF64-0537, AF64-0540, AF64-0544, AF64-17681, and AF64-18240, , AF64-14859 and AF72-1292 through AF72-1294 AF68-10935, AF68-10943, AF70-1260, AF70-1262, AF70-1264, AF70-1268, AF70-1271, AF70-1274 through AF70-1276 C-130H: AF74-1659, AF74-1665 through AF74-1667, AF74-1688, AF74-1692, AF74-2066, AF74-2072, AF79-0475, AF79-0478, AF79-0479, AF81-0627 through AF81-0631, AF82-0055, AF82-0057, AF82-0059 through AF82-0061, AF84-0204, AF84-0205, AF87-9281 through AF87-9284, AF87-9287, AF88-4406, AF89-9101, AF89-9104, AF89-9105, AF90-9107, and AF90-9108, AF83-0486 through AF83-0489 and AF90-1791 through AF90-1798, AF91-9141 through AF91-9144 and AF92-3021 through AF92-3024, AF91-1231, AF91-1232, AF91-1234 through AF91-1239, AF91-1651, HC-130N: AF90-2103