I have a 1971 Q 310. Does anyone have any experience with the shop at Oklahoma City. A/P does not hold altitude while engaged in Alt hold. I have checked for leaks but have found none. I am sure the auto pilot has never been overhauled or even looked at by a repair facility. Does something like that require a complete overhaul or can the box be bench tested and tuned? Any idea of the costs.
I fly a 1976 Turbo 310R with the 400B autopilot. I had a similar problem with my autopilot when I purchased my plane 3 years ago. I called Autopilot Central in Tulsa OK. I spoke to Bob who was incredibly knowledgeable with the 400B. He gave me several suggestions over the phone of things to check and observe when running the Auto Pilot before sending any AP items to them.
The autopilot would hold heading and follow the DG and LOC but would not hold ALT. I ended up deciding to remove the Control Unit, Altitude Sensor, FD Computer and Actuator and send them all to Autopilot Central. They were able to fix the motors and perform some Mods that needed to be updated and sent it back working 100%.
I have no affiliation with them, but have been very satisfied with their availability, service and turnaround time. However, plan ahead for AP service as they seem to have several weeks of repairs in the system when I speak to them. They will know if you have a good AP system worth servicing or not without wasting your $$ tinkering around with it to know where you stand. They are my go to shop for the 400B.
I’ve had several autopilots repaired by Autopilots Central. In my opinion they are the only place that I would let work on my autopilot. The owner Barry Starks and his staff really know autopilots. You are lucky that you’re so close to Tulsa. Give him a call.
I had the 400b autopilot for my 1981 340 overhauled at Autopilot Central 2 years ago. My local avionics tech removed it and reinstalled it. Turnaround was about two weeks and cost was about $2000. It has worked very well since then . Highly recommend their work.