Used Auto Pilot Questions

cessnadriver · #1 11-16-11, 09:07 AM

HELLO all.
I'm looking to install a "SIMPLE" heading auto-pilot in my '65 C337! I've done some investigation about STC used for like S-TEC, what a hassle! I understand that if I buy a used S-TEC I'd have to send the major components to S-TEC and have them re-certify them BEFORE they'll approve the system and send a new STC number for that installation. I was wondering if I could install a good used Cessna (ARC) auto-pilot with much less hassle-since My C337 had an ARC auto-pilot as an option?? Any thoughts? I also understand that the ARC auto's aren't all that great to begin with but, like I said, I just want a basic system. ANY and ALL help would be appreciated.
Thanks, BILLS bstory@pa.rr.com

Ernie Martin · #2 11-16-11, 12:45 PM

I'm not an expert so hopefully others will add to or correct my views.

First, the cessna/ARC units work fine. After 20-30 years the capacitors will leak and function will degrade or cease, but fix them and they'll work fine.

Second, installing the system in your '65 may not be easy, in part because there are at least 3 major units. The major units are the control panel under the quadrant, the electronics box on the roof (behind the headliner), and a unit in one of the booms. There are possibly many more related items throughout the aircraft.

Finally, it may be hard to find an IA who will sign off on the installation, given that it would take quite a bit of research to know with certainty that all the items that Cessna added for the autopilot were installed.

I'm not trying to discourage you. The systems work fine. I'm just alerting you that it may be a MUCH bigger job than you think and that it may be hard to certify.

Ernie

hharney · #3 11-16-11, 03:26 PM

Bill
If I understand your message above your specific aircraft has never had an autopilot? That makes things a little more complicated. Some of the older ARC systems in no longer supported, like my straight 400 is obsolete. I have a great avionics shop that has expertise with these ARC autopilots. I asked them several years ago to make some adjustments on it and after they looked at it he called and asked me if it was still working. I said that it was working fine but felt it could use some little tune up. He said that he was not going to touch it because he could not guarantee that it would still work. I choose to leave it alone and it still works today.

The next item I looked into recently was replacing or overhauling the DG. This ARC autopilot system is coupled to the DG. The DG tells the autopilot which direction the aircraft is heading. Again, as I did research I learned that this DG was no longer supported. It is made by AIM and is a 200-3. There is really no off the shelf replacement for this type of DG because of the connection with the autopilot and the autopilot is obsolete. To use a different DG like a Sigma-Tek would require some mods on the autopilot. My avionics shop again recommended that I overhaul the DG that I have and leave the system alone so that I don't end up with more problems than I started with. Some day when I decide to go the STEC route then change everything but spending the money on the existing system is not really encouraged because it's a dead end.

If your aircraft has never had a autopilot system in it then it would not make sense to put the ARC system in. It would be buying a unsupported component that is no longer is repairable. Just my thoughts after exploring in the last several years.

But don't just take my word on it, call the expert on these units. Bob Ferguson at Autopilots Central in Tulsa is the best guy in the business to talk to about autopilots. He has dealt with ARC for many, many years. He can help you with your options and give some thoughts on the systems that are out there. He can be contacted from their website at:

http://autopilotcentral.com/?page_id=20

Good luck, also search autopilots on this message board to learn what others have used on Skymasters.

jchronic · #4 11-16-11, 07:01 PM

I agree with the others that shoehorning an older, used A/P into your airplane would not be a small undertaking. With that caveat, I've removed the stock Cessna A/P from my airplane as part of a weight reduction program since I never use it on low altitude surveys anyway.

The couple of times I tried it after I bought the airplane, it seemed to work 'OK' (held heading & altitude reasonably well, etc.). I have the control head, elevator and aileron servos, and master unit (from up in the overhead). What I don't have freed up are the wiring harnesses, although I'm looking to see if I can snake them out somehow. You're welcome to it all for a hundred bucks + shipping, with no warranty expressed or implied as they say. And if I can get any of the wiring out intact, I'd send that along.

Joe
joechr@msn.com

hharney · #5 11-16-11, 10:42 PM

With that offer in mind and you have some time to tinker and install .............. might make sense

You would still need the DG unless yours has the output. If you get the model and serial from the DG you could find out. You can see the numbers from the avionics access hatch.

Joe, is that a straight 400 unit?

sns3guppy · #6 11-16-11, 10:58 PM

Many moons ago I was doing ag work in Kansas. My boss dropped an airplane off in Wichita for some maintenance, and I flew down in a Cessna 150 to pick him up. As we departed for greener pastures he commented that I ought to put on the autopilot. I glanced about, and not seeing one, cocked an eyebrow and asked about what it was to which he referred. He opened the little map box and withdrew a large, thick rubber band, and snapped it between the control yokes. Then he put on some headphones and fell asleep listening to deep purple.

I watched the airplane without scarcely touching a thing for the next while. A half hour went by and we stayed on heading, and trimmed up on a calm day, made almost no altitude change. After fifteen more minutes, the boredom was killing me, and I removed the rubber band.

Such a simple installation, too.

Flying the skymaster isn't much different than that 150, when you think about it.

You did say "SIMPLE" installation, didn't you?

cessnadriver · #7 11-17-11, 05:57 AM

Hello ALL.
I understand that what I had proposed was a little crazy, but I wanted to know you guys' thoughts. It pretty straight forward that most are against it. I don't exactly know if my bird had an auto-pilot in it due to MOST records are gone. I do see some kind of multiple-pin "cannon" plug in the wings and booms indicating , maybe, an auto-pilot was installed at one time. I certainly DON'T want to put $5000-$10,000 into a single axis auto-pilot to help relieve some of the pilot chores!! I appreciate your thoughts.
BILLS

jchronic · #8 11-17-11, 09:11 PM

Re "Joe, is that a straight 400 unit?"

Correct Herb, a straight Nav-O-Matic 400. Appears to have been a factory installation by the routing of the wiring harnesses; they're pretty well embedded in the airframe, hence my caution about being able to get them out intact.

Joe

rick bell · #9 11-17-11, 09:18 PM

Quote:

Originally Posted by cessnadriver

HELLO all.
I'm looking to install a "SIMPLE" heading auto-pilot in my '65 C337! I've done some investigation about STC used for like S-TEC, what a hassle! I understand that if I buy a used S-TEC I'd have to send the major components to S-TEC and have them re-certify them BEFORE they'll approve the system and send a new STC number for that installation. I was wondering if I could install a good used Cessna (ARC) auto-pilot with much less hassle-since My C337 had an ARC auto-pilot as an option?? Any thoughts? I also understand that the ARC auto's aren't all that great to begin with but, like I said, I just want a basic system. ANY and ALL help would be appreciated.
Thanks, BILLS bstory@pa.rr.com

the best autopilot is _____ YOU

these fat broads trim out beautiful and only need a nudge now and then
you never would put a harness on your spouse when a little tender nudge will do.
but what do i know

jchronic · #10 11-17-11, 09:26 PM

Can't disagree with that observation. When I picked up my airplane after purchase, ferried it from Indianapolis back to Mass., just shy of 5 hours en route. Tried the A/P briefly just for fun but hand flew most of it and ate lunch along the way. And our surveys can go up to 5 hours and on the straight & level portions it pretty much flies itself. They do trim out beautifully - if they're rigged OK.

Joe

cessnadriver · #11 11-18-11, 08:43 AM

Okay guys- I understand it trims "beautifully". I fly for the Civil Air Patrol were most of my flying is two plus hours shuttling aircraft to and from maintenance. It's nice to set the old auto (it only has heading axis) and enjoy the flight and eat my lunch, knowing my return trip will be without an auto and having to make many stop along the way. I just figured with having a powerful twin, it would be nice to have an auto to help the flight along.
Thanks for the replies.
BILLS
(NEWBY SKYMASTER OWNER)

sns3guppy · #12 11-19-11, 01:26 AM

The skymaster is a powerful twin?

cessnadriver · #13 11-20-11, 01:39 AM

TO: sns3guppy
Yes-for a single Cessna driver A Skymaster would be a powerful twin to me.
BILLS

Red Air Rambo · #14 11-21-11, 10:26 PM

Quote:

Originally Posted by cessnadriver

TO: sns3guppy
Yes-for a single Cessna driver A Skymaster would be a powerful twin to me.
BILLS

+1 coming from a 182, but I used to fly an F-16 and the power that the Skymaster has works great for me!

I just don't see anything out there that can do what it does.

sns3guppy · #15 11-22-11, 11:12 AM

I guess I'm not seeing it. Many light twins exceed the Skymaster in performance and power. The C337 is a great little airplane, but it's neither powerful nor a top performer.