Per a 1968 Navomatic 400 repair manual:

Computer-Amplifier part number 30520-0014 (14 volt) or 30520-0028 (28 volt)
Control Unit [dial unit on the pedestal] 30510-1114 (14V) or 30510-1128 (28V)
Gyro-Attitude Indicator 30475-0100 (Type G-519A)
Directional Gyro 30370-0100 (Type G 520A)

Above for an "AF-520A".
Herb's pictures for "AF-520 B&C".
Hope this helps some. I see a firm called AQI that sells them and overhauls. Maybe there are others...

I hear you, Bill; I will be 67 this year, but at any age, having an autopilot, even a basic wing leveler, is worth a lot in a single-pilot operation. It gives you time to do many things, including watching for traffic and other tasks on any flight.

My vote would be for Autopilots Central. They run a schedule and seem to stick with the expected finish date. My work was supposed to be done at noon on a Friday (their normal end of week closing time), but everybody stayed until 5 pm to make sure I got out. They did this for me without over-time shop hour charges.

I see that you are in NE PA, so Tulsa is a long flight. My thoughts or at least a question for any shop working on a 400 is, "are you going to tune it to the airplane on a check flight?" Two shops in Texas were honest with me by saying: we are going to pull everything out and send it to APC, and your airplane will sit here while APC goes through your gyros and boxes. What we won't be able to do is tweak it inflight when we put it back together."

As in a post I made concerning my autopilot work at APC, twice as much was found after the test flight as were found at the bench. This lead to some small components being replaced. I wanted to fly the flight with the two technicians but was smart enough to let their pilot do it as I figured he had seen it all. It was a smart move as, after the first flight, he told me all that they do on the flight (about an hour's worth of flying), and he showed me his kneeboard with notes; a lot was going on that I would have never thought to look at, let alone understand. The pilot was a Cessna guy, and he said he probably flew the acceptance flight in my airplane as it rolled out.

In that other topic, I also relayed how it takes two technicians in flight, one in the right rear overhead of the airplane, one upfront, to do what they do. These two fellows have a couple of unique "boxes" that they have made over the years of 400 work that help them fine-tune the beast.

When looking at other shops and their bids on your work, ask them if the actual 400 bench setup and testing will be done in-house and will they be accomplishing the inflight adjustments. The first will unnecessarily increase the downtime on your airplane if sent off, and the latter will not provide a finished product.

I had found a complete Cessna bench setup for sale, the same boxes on the APC bench (not the inflight boxes), and offered to buy it for my shop. The guy that works on my airplane didn't want it as he said there was more to it than that. He said, "it's too late to acquire the knowledge that an outfit like APC has." At least APC is training the young guys.

With the certain schedule that APC maintains, I bought a round trip ticket on United from Tulsa to Victoria, TX, and back. It was the cost of one night's hotel and meals. In that my wife and I go to St. Paul twice a year to see family; with a stop in TUL, we are going to plan an overnight on the early fall flight so that APC can keep the 400 tuned up. I spoke with the boss; he thought it a great idea as too often so many are letting their 400s go. He felt the 400 is better than the alternative.

My freshly overhauled AI was bad; still, in warranty, I found a replacement in TUL (Porter-Strait Instrument Company) and returned mine for warranty as I would like one on the shelf as a failure ends 90% of my flying. APC suggested that when returned, I send it to them to adjust the nulls as it will not come from the instrument shop ready to slide into the Skymaster and it's 400. It's not a complete 400 tuneup, but it will keep me going until I get back to TUL. I still haven't received the AI back, but when it does, I will slap a label on it and send it to TUL. I have a T&B on the shelf that needs O/H; I will send it to PSIC as well; I liked how they worked with APC and the help they offered to get my airplane out of the shop!

Yep, $10K is probably worth it all considered!

Navomatic 400
 

TO: Patrol Pilot.
Thanks for the reply.
A hangar neighbor suggested Autopilot Central, as he had them do some component work for him. So I contacted them. Randy the old mechanic said "we no longer work on the 400!" Yep, that's what he said, he mentioned that they WOULD work on it but basically if I needed parts I'd be screwed?? So I contacted Mayday Avionics in Grand Rapids, MI. Suggested by a SOAPA member. The main tech there called me and said he had a lot of experience with the 400s. He also said that they have an electronic engineering company that makes several problem components in the amplifier, ie, transistors and resistors, that are the usual replacement parts needed. I'll have to ask about the test flight. As I said earlier, that shop is much closer. I haven't decided which shop I'll be going to. Have to ask more questions to each shop before making my choice.
Thanks for your assistance.
Regards, BILLS
PS: I live in NW Pennsylvania, between Erie and Pittsburgh.

Navomatic 400
 

wslade2 .
Thanks for the reply. Is the AF-520A the amplifier? The reason I'm asking is if that number is for the amplifier? Because my number is CA-520A?
Thanks, BILLS
PS: Do you have the SECTION 2 manual? The Section 3, which Herb sent to me is for 1968 model year, mine is a 1965.

Ahhh... the straight 400, no A or B.

I am trying to attach a PDF file of a few salient pages from the manual to see if this helps find the parts you need.

Handwritten on the front of the manual is "1968 AF-520A" which I surmise represents the straight Nav-o-matic 400 model this manual is for. You will see the Amplifier is "CA-520A", the number you have on your amplifier.

Hopefully, if I am successful, there is a PDF file attached to my post.

Also, here is a listing of the proper actuator numbers.

Attached is another PDF

Navomatic (straight) 400
 

wslade2.
Thanks, that is part of the manual I was looking for. I'd assume the avionics shop will have the rest for when I send them my components.
TO ALL: Many thanks to you guys' help!! Many think I'm crazy trying to get an an OLD straight 400 autopilot back in my airplane? But I always enjoyed flying(Civil Air Patrol's airplanes) with at least a single axis autopilot on long trips.
Any other thoughts or help from my fellow SOAPA members would great.
Regards.
BILLS

Our Skymaster is at Mayday right now. We have a Bendix FCS810 that has been intermittent. They told us when to drop it off and started working on it the next business day. As you mentioned, we had a FET fail and their electronic company is making some replacements. They've been great to work with.

Bill

Navomatic (STRAIGHT) 400
 

Patrol Pilot.
Thanks for the reply.
I have a straight 400. The earliest model. NO A or B. I do have another 400 which I'm trying to determine which one it is? I'm sending the pictures and serial numbers to Mayday Avionics, hopefully they can figure this out. I have a dual knob DG I'm hoping that will work with the second 400?? Who know!