Jake@BevanAviation

The autopilot configuration page should be set for KI525 and at default values, the flight director page should be set for KI256 and at default values. The GAD43 gyro emulation type should be KI256. You need to align the flight computer to the GAD using the GAD output test. You should follow King installation bulletin 430 using the King flight line test set (KTS 150). If the KTS150 is not available you can fabricate a breakout harness. The GI275 IM shows how to make this harness if needed.

We had this happen before. Turned out to be the GSU25 had a issue.

I would check the output of the transducer inside the flight computer if the aircraft was here. You can remove the static line to the flight computer and attach a hose to the unit. When applying pressure or vacuum to the hose the computer should respond in the opposite direction. For example with a level attitude source or the ADI unplugged. If you applied pressure to the static line the computer should want to climb to get back to target altitude. If you create a vacuum the system should want to descend to get back to target altitude. You can do this with your mouth as the system is very sensitive to pressure changes. This would test to see that the transducer assembly is functioning. NOTE: there is a interlock circuit in the computer that if there is an issue with alt hold it will not allow you to select the mode and you will not get the annunciation of ALT on the bezel.

@Wingover There is a small dc motor that is attached to the drive motor inside the servo assembly. It provides negative feedback to the computer to tell it the direction of rotation and how fast. If the tach feedback motor is inop the servo will end up over driving causing a 1-2hz oscillation. Sounds like you might have a pitch servo issue. If part of the transistor bridge fails it will cause a hard pitch over or no drive in one direction. You can test this by using the UP/DOWN rocker in the computer to change the pitch attitude. You should be able to set a climb or descent attitude and the computer hold that attitude. When activating alt hold the computer takes the attitude information and the output of the altitude transducer to maintain a selected altitude.

@Wingover A slow drift, a oscillation, hard pitch up or down? If you have a video of the issue maybe that would help. Most common issue for a slow drift would be servo startup voltage, a 1-2 hz oscillation would be failed tach generator, a hard pitch up or down would be failed transistor drive.

Altitude hold information comes from the transducer that is internal to the KC192/KC191. Can you give more detail on what issue you experienced with alt hold in flight?

Base unit GI275's can be purchased over the count and installed by a AP. ADAHRS and ADAHRS+AP units need to be purchased via a Garmin dealer. Base units are typically used for CDI, MFD, HSI, EIS functions. They do not have the second connector that is used for legacy autopilot interface and do not have ADAHRS functions.

I would have someone listen to the motor speed when operating the trim system on the ground. If the motor is slowing down I would expect a increased load on the servo. If the load is too much eventually the slip clutch would start to slip. When was the last time the trim controls were inspected and lubed? Running trim by hand do you notice a area where there is increased friction? The servo would have to work against the increased load when using MET (manual electric trim). We have seen several Mooney's where there was excess friction causing the trim drive to slow when using MET. Cleaning and proper lubrication of moving parts tends to resolve this issue. If the motor speed doesn't slow I would expect a problem with the slip clutch assembly. I can tell you what the slip clutch torque limit should be if I have the model and SN of the aircraft. There is a slight possibility that there is a issue with the voltage regulator in the trim servo. Normally if the voltage regulator is soft the trim servo drive is very slow or INOP.

New GI275's come with a 10 hour trial of SVT. If you like it and want to add it there is a unlock that is needed. GI275's do a lot more vs G5 and interface with more equipment vs G5. Depending on the equipment in the aircraft the GI275 could have a advantage over the G5.

Make sure the installation shop you choose knows how to do the alignment to the KAP150. The process is outlined in the Garmin IM for the GI275 when interfaced to the KAP/KFC 150 system.

The only approved display replacements are the mod kits produced by Honeywell that change the old gas display to a led. Honeywell, continues to increase the price of this mod kit so it has become more costly to fix these units. We have had very few issues with the LED mod by Honeywell. There is another person that advertises an OLED replacement. However, this is not an approved mod, if you choose to do this good luck getting someone to sign off on the radio if it would need any future repairs. We have seen a couple of them come in and we have rejected the units due to no service data being available. The frequency knob issue is pretty common as these units continue to age. It is fairly easy to replace pending the parts are available and the repair shop knows what they are doing. With the repair cost increasing more people are replacing the units with new modern radios. The GNC215 by Garmin is a good option and you can buy them over the counter. We have installed several of them in multiple aircraft with no issues. The KX200 is advertised as the replacement to the KX155., but we have yet to see one in the wild. I have heard that the unit are finally available after being talked about for a couple of years. We still repair the KX155 units and have the LED mod kit available. The thing that really makes the units non repairable is when they have capacitor leakage and it spreads damaging multiple circuits in the radio. This capacitor issue is more common in units manufactured between 1991 and 1998.

@Guillaume see attachment. 006-00396-0000_4.pdf

With the A/P engaged and the A/P lever switch in the up position on the KC290 control head, the lateral axis and the pitch axis should have the controls locked in place if you try to move the yoke. The controls are locked when the solenoids in the servos latch. The solenoids should latch when the autopilot is engaged. With a KFC200 system there is a single solenoid engage voltage that is sent out of the computer and paralleled to all the solenoid's. Do you happen to know if you have the 100 series servos or the 200 series servos? Inside the KC295 on the power supply board are two transistors that develop the solenoid engage voltage. These transistors can fail and there is a very small trace that runs down the edge of the board that can open with high current pull. I would have the avionics tech look at the system interconnect and verify the engage voltage from the computer. If the engage voltage is there and the solenoids are latching the next check would be the slip clutch in the servo capstan and the bridle cable tension to the push rod/bell crank.

Just as a FYI this is not an approved mod from the MFG. We have seen a couple over the years and we will not even attempt to do a repair as the unit is modified outside MFG specs and no longer matches any approved documentation from the MFG. Honeywell does have an approved LED mod that is still available to fix display issues experienced with the old gas discharge displays.

With Century Flight Systems out of business a lot of the parts for that system are very sparse. You might get lucky finding something at a salvage shop but in my opinion it is on a short time line until there is no support for that system. Not to mention finding the correct installation documentation for the aircraft. At this point with the limited parts we have for the Century 21 and 31 systems I am very reluctant to try and repair them. Also, if you require a EASA release your repair choices are going to be drastically limited.

@LANCECASPER We would not be interested in any deviation from the STC on a flight control system.

Per Garmin SB 23024 rev A, they will pay 2.5 hours of labor per warranty servo replacement (011-02927-11 and 011-02927-21 non mod1). You can submit a request for more time depending on the location and air-frame but is at Garmin's discretion for approval.

@Austin305Rocket Only way to get replacement parts would be someone that has old stock or from a parts unit. My guess is something has failed in the switch assembly. I would have to look Monday to see if I have any good parts units. If you can bite the bullet and do the GFC500 that would be ideal. However, if you need more time try looking on eBay for parts units. Our minimum charge to evaluate a unit is $270.00, I will look for used parts Monday morning, if I have something I will send you a PM.

@Will.iam Give us a call and ask for Zach, he should be able to help with button key lighting.

You might want to provide a panel picture of the current layout. Inter-connectivity is huge when trying to plan a panel upgrade. Some devices only take certain signals from navigators like ARINC 429 or RS 232 (example G5 to GNS430W). Others can take analog signals from legacy navigators (example GI275 to KX155). Some manufactures play better with legacy equipment vs others. If you have a legacy autopilot you defiantly want to make sure the new equipment can provide all the signals the legacy autopilot system needs. To be completely honest, we are mostly a Garmin shop. We have done several installs of G5's, GI275's and G3X's in Mooney's. Some customers have got Aspen's as an alternative. We rarely put in the AV-30C due to the units limitations. However, if it fits the scope of the job it is a viable alternative. Using the 1:1 ratio of equipment to labor is pretty good to get you in the ball park of installation cost. We tend to be about 65-80% of equipment cost for labor/parts depending on the complexity of the job. If you have questions about the inter-connectivity of the ship give me a call or a PM and I will help as much as I can.

Pull the unit out of the rack (KC192) flight computer. Be sure to remove the static line to the transducer first. On the back of the unit around the transducer port there should be a red or black 4 digit stamp. This is the year and week the unit was manufactured. Units made between 1991-1998 have capacitor leakage problems. This is becoming more common with time. I have 3 units here all with the same problem, leaking capacitors. The capacitors that always fail are black and say IC on the side. Depending on the severity of the capacitor leakage it can cause units to be beyond economical repair. The leaking electrolyte can cause the system to not pass PFT or have weird annunciation/functionality.

@PeterRus I believe the Nav and G/S are different meters. I have not seed that many issues with the Nav flag function but G/S is a different story.

What HSI do you have? The KI-525A has a known issue of the G/S needle getting stuck from time to time. I would give Mike or Tom a call to discuss the KX-165, there are some units that have capacitor leakage issues that can cause weird failures and be isolated to specific circuitry.

Give us a call Monday and ask for Zach or Mike. The black horse shoe sound like the display backlight and yes there is a fan that can fail.

I would need to know what step the PFT fails on. Best way to troubleshoot that system is with the diagnostic cable and laptop. For service you are going to be limited to Mid-Continent Instruments, Duncan Aviation, and Southeast Aerospace. Honeywell in their infinite wisdom restricted repairs to only authorized service centers.