Pirep for Bevan Aviation - re KFC150 autopilot

[Will.iam]

So My KFC-150 with the original HSI and ADI has always been reliable except my ADI would lean 5 degrees to the right even though the autopilot would fly straight and level but the NAV function never worked right.  It would goto 30 degrees off of the course and then hold that offset which was annoying but I would just use heading and steer for crosswinds myself. Eventually with the ADI slowly erecting and never shaking out I sent the ADI out to get overhauled.  When I got it back the ADI was great; shakes out nicely on startup and is very quick to align within seconds of engine start, but the autopilot would occasionally not hold altitude and I would get a little yoke pump every now and again which was a new issue I never had before the overhaul.  I tried cleaning the yoke shafts as others have commented on the shaft sticking can cause the yoke to pump but that did not clear up the issue.  Jake from Bevan aviation that frequents this site stated that after any overhaul of the ADI you need to match it to the autopilot.  I did not realize this was even an issue or possibility but I scheduled an appointment and flew up there one early morning to arrive right at opening time at 8am.  They took out the KFC-150 and ADI and put them on the bench and proceeded to match them.  One of the big things Jake noticed was my roll steering output was way below specs I think he said it was 2 or 3 volts when it needed a 5 volt signal.  He turned up the voltage adjusted the gains and reinstalled the head unit and ADI.  This was right after lunch and I was headed home by 1:30pm.  I immediately noticed a crisper response and feel to the autopilot and it has captured and held altitude consistently with no yoke pump ever since.  but the huge  added bonus is my NAV function works correctly now.  Who knew?!? even the previous owner had given up on getting the nav function to work and thought it was a loose or broken connection wire but it was just the ADI not matched to the autopilot.  I don't have GPSS steering but the Garmin 530W does give crosswind corrections so I no longer have to do minor heading corrections like I did with the heading bug.  So if you are experiencing an small minute altitude oscillations known as yoke pump and you have cleaned the shafts and they feel smooth when moving them it might just be your ADI and autopilot need a match tuneup.

 

[INA201]

Great PIREP. I had really good luck with a century 2B being rebuilt by Bevan too.  The GPSS with the 2b was a great first step into the 21st century(no pun intended with the use of Century).  

[LANCECASPER]

9 hours ago, Will.iam said:

So My KFC-150 with the original HSI and ADI has always been reliable except my ADI would lean 5 degrees to the right even though the autopilot would fly straight and level but the NAV function never worked right.  It would goto 30 degrees off of the course and then hold that offset which was annoying but I would just use heading and steer for crosswinds myself. Eventually with the ADI slowly erecting and never shaking out I sent the ADI out to get overhauled.  When I got it back the ADI was great; shakes out nicely on startup and is very quick to align within seconds of engine start, but the autopilot would occasionally not hold altitude and I would get a little yoke pump every now and again which was a new issue I never had before the overhaul.  I tried cleaning the yoke shafts as others have commented on the shaft sticking can cause the yoke to pump but that did not clear up the issue.  Jake from Bevan aviation that frequents this site stated that after any overhaul of the ADI you need to match it to the autopilot.  I did not realize this was even an issue or possibility but I scheduled an appointment and flew up there one early morning to arrive right at opening time at 8am.  They took out the KFC-150 and ADI and put them on the bench and proceeded to match them.  One of the big things Jake noticed was my roll steering output was way below specs I think he said it was 2 or 3 volts when it needed a 5 volt signal.  He turned up the voltage adjusted the gains and reinstalled the head unit and ADI.  This was right after lunch and I was headed home by 1:30pm.  I immediately noticed a crisper response and feel to the autopilot and it has captured and held altitude consistently with no yoke pump ever since.  but the huge  added bonus is my NAV function works correctly now.  Who knew?!? even the previous owner had given up on getting the nav function to work and thought it was a loose or broken connection wire but it was just the ADI not matched to the autopilot.  I don't have GPSS steering but the Garmin 530W does give crosswind corrections so I no longer have to do minor heading corrections like I did with the heading bug.  So if you are experiencing an small minute altitude oscillations known as yoke pump and you have cleaned the shafts and they feel smooth when moving them it might just be your ADI and autopilot need a match tuneup.

 

That's great to hear. People chase these problems and I've heard of people spending many thousands at supposed autopilot specialists and it not getting fixed. @Jake@BevanAviation shows up here to patiently answer questions and they know what they are doing.

Do you mind sharing what it cost to have them get it right?

[KSMooniac]

That's a great bunch at Bevan... I'm fortunate to have them local to me and recommend them frequently!  BTW, you ought to strongly consider adding GPSS...huge increase in capability for very modest cost.  Even my lowly STEC-30 works great with GPSS.

[Will.iam]

2 hours ago, LANCECASPER said:

That's great to hear. People chase these problems and I've heard of people spending many thousands at supposed autopilot specialists and it not getting fixed. @Jake@BevanAviation shows up here to patiently answer questions and they know what they are doing.

Do you mind sharing what it cost to have them get it right?

They charged 2 hours for removal and reinstall of components and 2 hours bench testing and aligning. Their rate is $125/hr so 0.5amu 

[0TreeLemur]

In my opinion Jake from Bevan Aviation is a living GOD.     His willingness to share his experience on this site has helped many, including me.   Knowing that he exists helps me sleep at night.  As the owner /operator of a KFC-150 a/p this PIREP warms my heart.  Thanks for sharing @Will.iam