Jake@BevanAviation

@jaylw314 It can be repaired, typically we send the sticking needle issues to Mid-Continent instruments for repair.

It's not uncommon to have the G/S pointer stick on the KI-525. If the pointer gets stuck you can take the palm of your hand and bump the panel around the instrument. After bumping the panel they will drop into view and respond correctly until it gets stuck again. Only way to really fix this is have a instrument shop open the indicator up and clean/repair the G/S pointer assembly.

@goodyFAB The main problem with the Century 41 system is that Century is no longer supplying parts for the majority of the assemblies. This applies to all legacy systems they produced. Without the correct parts repairs will be extremely limited. The last discussion I had with the owner of Century Flight System they stated that they were no longer doing repairs at the factory. The Century 41 flight computer is full of ribbon cables that delaminate over time and cause major issues when trying to repair the unit. The last Century 41 I sent to Century for repair which had alot of ribbon cable issues and other board assembly issues came back with a 9k estimate for repair. This was a couple of years ago before they shut down factory repairs. I do have the test set and the manual for the Century 41 system but depending on the failure, parts might not be available. I would not be surprised to find delaminated ribbon cables inside the unit and I do not have any replacement cables for the Century 41. You can contact Autopilot Central and see what they say but they will have the same issue I have with parts unless they have a supply of new parts available. Century Flight Systems are in a pretty bad spot, with personnel retiring and no new trained techs for legacy systems available, no new products to market, it looks pretty dim for the future. What I tell any customer that has a Century 21, 31, 41 or 2000 is if the system is still working keep it going, but start saving for a future upgrade as part availability will severely limit the systems ability to be repaired and supported.

@pkofman I have not personally seen an instance where a failed KAS-297B would cause the KC19X flight computer to not pass PFT. The alt pre-selector was an optional system that could be added to the KFC150 system. It does get information from the flight computer system for oscillator and digital data. There is the possibility that if the unit were pulling the oscillator low that it could cause the flight computer to fail a PFT. If you wanted to isolate the KAS-297B out, I would just unplug the unit and then try the PFT on the flight computer. I would not be surprised if the flight computer you have has capacitor leakage in the power supply circuit. This is a known issue with units manufacture from 1993-1998. Are you getting the 12-13 flashes of AP on a successful completion of the PFT? Also, when the unit fails the PFT do you get the flashing trim fail annunciation or is the unit completely dark?

The KC19X is the model number of the flight computer. KC190 is a KAP100 flight computer. KC191 is a KAP150 flight computer. KC192 is a KFC150 flight computer. The individual part numbers of the flight computer will differ from model to model and are voltage specific.

King part numbers are 037-00032-0010 for 28v lamps 037-00032-0008 for 14v lamps

We do not work on the KAS-297B. I would suggest Mid-Continent Instruments, Duncan Aviation, or Southeast Aerospace for evaluation/repair. To my knowledge the only box that works in place of the KAS-297B is a GAD43e that is paired with the G500/600 glass displays.

To replace the lamps in the KC19X unit, the bezel has to be removed. To do this, the unit has to be opened up. Some of the screws are only accessed from the inside of the unit. Whoever replaces the lamps in the flight computer make sure they are spaced properly, if they are too close to the lens it can burn it over time. We do not work on the alt pre-selector (KAS-297B).

@WaynePierce 12-13 flashes of the AP light should indicate a pass. If the compass valid is inop on the GI275 it will not allow you to select any lateral guidance mode. Basic roll only mode should still work for wings level. On the side of the unit should be a red 4 digit stamp. Typically it is on the back of the unit around the transducer static port. For example 4685 would be the 46 week of 1985. Units made from 1993-1998 have capacitor leakage problems. This can cause issues with the unit passing PFT or allowing it to engage. There is also a current sense resistor in the computer that has very tight tolerance, if it falls out of tolerance it can cause issues with intermittent disconnects. Any time I get a KC19X unit in for repair I always replace the current sense resistor as preventive maintenance. Thom Duncan Avionics in Fayetteville is pretty sharp on the KAP/KFC150 system. If you need a shop to troubleshoot the aircraft that would be my suggestion. Another option would be a loaner unit, I might have something available but I would need to know what your dash number is. If you have any questions or concerns just give me a call.

@WaynePierce if you are able to get a video of the PFT sequence that would be very helpful.

For the KAP 140 when changing from a DG to HSI they have to be reprogrammed via a laptop. The KAP/KFC150 has sealed resistor modules that can not be re-strapped. They are specific for the air-frame installation and the flight computer options (FD or no FD, DG or HSI). If you went from a DG to a HSI the top resistor module would have to be changed. Any time you change the attitude source you have realign the flight computer to the new attitude source. This is even mentioned in the installation manual for the GI275. When you were doing the PFT test in flight did you get the proper sequencing of lights (4 flashes of trim, 12-13 flashes of AP)? If you did not get the sequence listed below there is something missing that the computer wants during PFT. Things that could cause a disconnect in flight are listed below. Faulty disconnect switch Faulty return springs in the MET switch assembly not returning the switches to center. Faulty gyro valid relay in the GI275 Activation of MET (manual electric trim) switch with the AP on Failure of the power supply monitor circuit in the KC191 Loss of compass valid from the GI275

@0TreeLemur I am pretty sure we have new knobs available. Give us a call Monday and ask for Mike, he should be able to give you a rough idea of what the repair cost would be.

Slow erection or excessive noise from the indicator are always signs that the bearings are worn and eventually the rotor speed will be to slow to maintain rigidity. Try to make note of the gyro orientation as the gyro is spooling up, a fresh overhaul always has a nice shake out of the indicator as the rotor speed is increasing. When the bearings get old and stiff you will see a reduced shake out or none. If you witness the AI no longer shaking out during the initial start of the aircraft, that is a sign that the indicator is getting worn. Always replace the filter when replacing the AI.

@VA FLYER I would assume someone would have to get approval from Castleberry if it was still under warranty to try and repair the issue. The instance I had was the AI would intermittently loose the roll output signal. I removed the AI from the aircraft and put it on the bench, gave it some excitation for the outputs to work, put it in a constant bank around 10 deg and monitored the output. Without influencing the AI I could see the signal drop out and come back after some time. This was in a Duke with a Century 4 and a replacement electric Castleberry AI for the Century 4 system. A shop in Florida had spent months trying to figure out the issue but with it being intermittent some flights were great, other not so much. The main issue was randomly it would start a oscillation chasing the heading bug but the longer the oscillation went the more drastic the banks would get. As the oscillation continued the aircraft would be doing large s-turns chasing the heading bug at a very aggressive bank. When the AI signal came back it would stop and track the heading like normal. If this sounds close to what you are experiencing I would suggest to have the AI put on a bench and have it double checked for intermittent outputs. This can also be done in the aircraft but it won't be easy. If you need a shop to help troubleshoot this issue I would suggest talking to Jason at Freedom Aviation in Lynchburg VA. I have been working with Jason for years helping them troubleshoot autopilot issues. If you want to chat about the issue just give me a call.

@VA FLYER I have seen a couple of Castleberry electric replacement AI's have issues with solder joints that have caused this same behavior. If it was me I would be checking the AI on the bench and looking at the output. The FD bars are a representation of what the flight computer is commanding.