Jake@BevanAviation

The IDF540 sends lateral and vertical deviation for VOR, ILS and GPS navigation to the HSI, typically there is a parallel to send the same info to the flight computer. Modes like NAV and APPR rely on this information to fly the desired track. If you want a GPSS function the navigation data needs to changed and processed as a heading error. If your current HSI does not have a built-in GPSS function like a Aspen or Garmin G5 or GI275 ect, you will need a magic box like the GDC31. This magic box takes the lateral deviation from the navigator and turns it into a heading error for the flight computer. The en-route tacking is all done under heading mode on the flight computer. When you need to fly a approach you will still have to switch to approach mode when needed. The system is capable of flying the navigation data as a GPS way-point but you wont be able to go completely hands off like you would if you had GPSS. Flying a GPS way-point with the flight computer in NAV mode you still have to adjust the course pointer when prompted by the navigator. Possible issues you might experience when using NAV mode to fly a GPS flight plan could be reduced bank angle when trying to track the en-route on a large turn. GPSS eliminates this issue due to the system being in heading mode for the en-route tracking of the flight plan.

First thought is you mention 4 flashing lights (trim) then nothing. Typically when this happens the unit is still stuck in self test mode and not issuing a fail or pass command. There are 2 relays on the top board that deal with the ramp rate test for attitude. I have seen these fail and produce the same result. If the unit has been removed from the rack I would suggest double checking the pins and re-racking the unit and then test again. The fact that you at least get some flashing lights means the unit is working just stuck somewhere in the PFT mode. If the shop has the flight line test kit i would suggest getting the unit out and testing it on the bench with the test chips. That should be able to narrow down the issue with the unit. NOTE: as long as the dash number is not -15 it will work with the flight line test kit. If your unit is a dash -15 the only shop that can test it is Duncan. The only think I can think of is maybe the EA100 could have a issue with the interconnect relay for attitude valid. If it is working properly you should get bus voltage on P2 pin B at the flight computer. Pushing the disconnect switch or the EA100 becoming invalid should remove this voltage.

A yoke mounted disconnect switch is optional equipment per the factory maintenance manual. Might be worth a call to Century to see if the optional part is still available.

Ideal startup voltage after overhaul or cleaning and bearing replacement is around 800mvDC. Typically anything above 2VDC is getting in the area of high startup voltage especially on a 14v system.

So the best way to adjust the roll threshold is to max out the pot until it produces a slight roll oscillation and then back it off until the oscillation stops. There is a product that Bob has suggested to me and I have started using that works wonders with connector pin issues. Stabilant 22, you can find it online. I have been using it for about a year and had great results.

Winchester connectors used to have a machined 4 pin female connector that worked great but I have not been able to locate the connector for some time. Using a small pick you can push the female split pins back together. Sometimes this will fix the intermittent issues that are connector related.

For the sticking solenoid I would have the tech check the travel of the solenoid and possibly adjusted the solenoid alignment so it doesn't get stuck when releasing. I have seen this happen in the older style of solenoids but in the revision they added a plastic insert to try and prevent this.

Double check that the gyro alignment was done on the new KI256 and have them look at the tach feedback from the roll servo. Tach generators in the roll servo can go bad and produce roll oscillations.

Seen it happen before in a JetPROP with a KFC 150 system. Turned out to be something wrong with the pitch servo. The aircraft flew fine the bars would just bounce all the time for pitch. Swapped the pitch servo out and the problem went away.

If the drive motor is running (pins C and D) the solenoid is on (pins A and B). A simple voltage check with the servo connector with a multi-meter will show where the issues is. With the meter on the ship side pins A and B (ground) when the roll rocker is pushed up the solenoid should get buss voltage. You can also test the servo with power-supply if needed. The 4 pin connector are notorious for being intermittent. If you are still having issues just give me a call and I will help with troubleshooting as much as possible.

If the attitude source has been change by replacing or repairing the KI256 the gyro gains need to be adjusted. This is done with the KTS 158 test set. Any shop that has this test set should be able to set the bank back to 20 degrees.

The KC 295 is still available for field service and is not required to be returned to the factory for repair. There are some components in the KFC 200 system (KS271A,KS272A) that would need to be repaired at a authorized repair center. Duncan Aviation, Mid-Continent Instruments, Southeast Aerospace and Precision Aero are the approved repair centers for certain components

Well if you have 2 KC 295 flight computer you could possibly make one good one out of the two if they are the same dash number. I would have to check specifics on board compatibility. If you have any questions just give me a call.

If that is the repair for just the KC-295 flight computer it seems excessive.

Good to hear that the adjustments to the radio coupler worked for you. If you have any additional issues just let me know.