I wanted to post this as it may help someone who has been experiencing an issue with the bank angles being too large/too small with the KI 256 and the KFC autopilot.
Short story: My KI-256 went bad and it was replaced with an overhauled unit. My KFC 200 A/P worked flawlessly prior to the KI-256 failure. After KI-256 was swapped out everything worked fine BUT I noticed the pressure gage (Bonanzas have pressure systems not vacuum) reading slightly high (top of green arc).
Here is why I made the fatal mistake and broke the cardinal rule “if it ain’t broke, don’t fix it” and replaced with my own rule, “if it ain’t broke it, fix it until it is!” I adjusted the regulator to bring the gage into the middle of green arc. BIG MISTAKE. The vaccum/pressure regulators are set/calibrated during manufacture and really should not be touched as they are VERY sensitive.
After “fixing” my gage reading problem my max bank angle with A/P on went to 30 degrees. Too much. Unfortunately at that time I did not link in my mind that my adjustment of regulator caused it so I tried to “fix” it by adjusting the roll gyro gain on the KC 295 computer. No joy. Even at the least gyro roll gain, the bank would still go to 30 degrees. Then, finally, I replaced the pressure regulator and noticed my max bank angle immediately lowered to about 16-18 degrees. That is why I realized the culprit was the defective pressure regulator. Finally, I adjusted the gyro roll gain back to specs as shown in the maintenance manual and voila the max bank angle is now 22 degrees and everything works perfect again.
The moral: DO NOT TOUCH the vacuum/pressure regulator. If you adjust it, you may permanently damage it (as was the case in my case).
Update: the tweak works but 8mH was needed. So it is considerably nonlinear.
