Nav-o-matic 300 autopilot

William Pete Hodges

William Pete Hodges

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My 1964 Mooney has a factory installed ARC Nav-o-matic 300 autopilot. It was working properly 5 years ago when I bought the plane, but only in warm weather. This unit has a dedicated gyro behind the baggage compartment for roll and yaw control and I figured the grease in those bearings had gotten old causing the problems in cold weather. I pulled the gyro and sent it off for rebuild. The system, hasn't worked since reinstalling it. I even sent it back to the rebuilder with no luck.

This autopilot is mounted under the panel on the hump of the floor between the front seats, not in the panel. I only have one picture showing its location. While I don't use it, I would like to bring back its capability to the cockpit. The idea is to have all the functionality of the original airplane when I eventually stop flying and sell it.

Has anyone dealt with this system and either had it repaired or replaced it with something else? I know the experience pool for these is getting pretty thin as older technicians retire and more. I figure there were plenty of them around as they were the standard for Cessna for years,

Thank you in advance for your time and help.
 

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William Pete Hodges said:
My 1964 Mooney has a factory installed ARC Nav-o-matic 300 autopilot. It was working properly 5 years ago when I bought the plane, but only in warm weather. This unit has a dedicated gyro behind the baggage compartment for roll and yaw control and I figured the grease in those bearings had gotten old causing the problems in cold weather. I pulled the gyro and sent it off for rebuild. The system, hasn't worked since reinstalling it. I even sent it back to the rebuilder with no luck.

This autopilot is mounted under the panel on the hump of the floor between the front seats, not in the panel. I only have one picture showing its location. While I don't use it, I would like to bring back its capability to the cockpit. The idea is to have all the functionality of the original airplane when I eventually stop flying and sell it.

Has anyone dealt with this system and either had it repaired or replaced it with something else? I know the experience pool for these is getting pretty thin as older technicians retire and more. I figure there were plenty of them around as they were the standard for Cessna for years,

Thank you in advance for your time and help.
Click to expand...
Actually there were not plenty of them around. Most Cessna piston airplanes of that era were sold without autopilots. Cessna sold ARC in 1982.
 
From your description of warm weather only operation, the problem is more likely to be in the servo, not the gyro. The lubricant there may have become so stiff that they no longer function.

I have flown several Cessna's with Navomatic, and liked them, but I earned my PPL to fly planes, not watch them fly themselves. Great for briefing the approach one last time.
 
How much money do you plan on spending to get the Nav-O-Matic working?

Auto-Pilot technology has jumped leaps and bounds. Keep in mind that replacing the Auto-Pilot system with a modern digital system will increase the usefulness and value of the aircraft. Even after you get the Nav-O-Matic working perfect it has limited use compared to any modern Auto-Pilot.
 
I’m not sure on the cost to rebuild the servos. On my now replaced KFC 200 autopilot, the servo rebuild cost was basically the same as the hardware cost for a GFC500 (minus install cost of course)
 
I am OK with replacing with new if necessary. I was hoping someone here had some experience with that.
 
If you're selling, even pretty far in the future, I'd be tempted to do nothing. If you want to have a functioning AP, then I'd get something more up to date. You will not recover your investment in a new AP, so only do it if you plan on using it.
 
eman1200 said:
nav. o. matic.

sure would love to get paid to name stuff like that.
Click to expand...
You just came around too late. Around 1960 lots of products and companies then were named something-o-matic. Some still exist. The Bunn-o-matic Corporation, founded in 1959, still sells the coffee makers that you commonly see behind the counter in lots of diners.
 
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