Navomatic AF-420A
 

Have this AF-420A a/p unit in my plane, and previously only gave me heading bug track (hooked up to a NSD 360 HSI)...but after new avioincs install AND HSI overhaul, it now does not seem to work correctly. When tearing out interior for the annual I noticed a switch on the back of the unit that says serve and has in or out...I can't find a manual anywhere online to figure out the correct position of this switch. While I can try ti both ways, I was hoping someone might have a pdf they can share online for this a/p.

https://www.esscoaircraft.com/p-948-...rs-manual.aspx

http://www.ebay.com/itm/Cessna-ARC-N...-/380698999478

Robert, the last time I asked my radio shop to do some adjustments on my Navomatic 400 they asked me if it was working and I said yes and they said good, because we don't think we should touch it. These units are getting really old and most shops are shying away from them because they can't fix them after they touch them. Call Autopilots Central in OK, they are about the only guys that might be able to help you

manual on order
 

Thanks Herb...i needed the users manual, so ordered the download version from esso (via your link). Hopefully will be ready to grab shortly. The install manual on ebay for 200+? wth?

anyway - yep, if I hit the powerball I will get a new a/p....but really I am ok with just the heading bug stuff working. it was working fine until I replaced my stack and in parralel had the hsi overhauled, so thinking it was something done.

In 2009 I had King Avionics out of UT work on it, out of the plane, and got it working with the HSI. I found their notes and schmatics, so hoping I can figure this out once i have the user guide in hand.

But while we have this thread fresh....

let's all discuss the current state of buying an a/p for our planes....

what do you all know? at one point when i first started flying 11 years ago, you could buy a used STEC off of ebay and install it in another plane...then they made it difficult to do so...they required you to go back to the mfg and get a STC issued for your plane, as opposed to where it was originally installed...pricing it the same as new...killed that market.
I heard a couple of years ago this all relaxed again, and you can buy a used a/p from ebay,wentworth,texas air salvage, etc and install it? Might be FSDO specific?

On a related note - I heard of a FSDO note out of TX that talked about the ability to replace any part in planes past a certain age with a part the IA feels increased safety, without it being certified for that plane...I've heard tell that you could easily replace some parts with newer better stuff, and cost effectively, as long as the IA felt it increased the safety of the airplane. Urban myth? FSDO specific?

ok, let's all chat :)

420AF gyro switch on back
 

OK, go the operators manual for the 420AF....but it does not reference the gyro switch on the back of the unit, and correct position for it. If anyone has that info, would appreciate it. Buying the 200+ install manual off of ebay is a little extreme just to find that correct switch position.

Autopilot
 

Muncie Aviation at Muncie, Indiana airport still works on the 400 unit. Get all my autopilot work done there and they do a good job. Give them a call and talk with someone in the avionics shop.

Good luck
Jerry

Not without an STC or a Field approval. STEC has to be STC'd for the plane so check their website for capability. I think the 55X is the main unit for us

STC auth
 

on a sep thread (on CFO) they talk about an FAA ruling in 2006 that says a STC holder must grant specific permission including plane s/n for use of its STC. That must be the move that caused the original change I mention in my post...ie that you use to be able to take a autopilot off a salvaged plane and use it on anther plane...then all of a sudden (and it 2006 seems right) you could not. But there are some advisory circulars since published that might make it work...like AC 23-27. This says that if you have a vintage plane (yes, my 1968 Skymaster qualifies under their definition), then you can replace old hard to find parts with something more current and safe as long as a STC or PMA exists for use on other aircraft (ie no car parts).
I am sure there are other methods of getting a new experimental but safe autopilot to be used on our planes, or perhaps a certified (like STEC) used autopilot.

Anyone have any experiences where they got a 337 approved, or otherwise got an autopilot legally in their plane without going bankrupt? :)

let the opinions and rants flow....

Navomatic Autopilot
 

I have copies of the Navomatic Owners Manual, Parts catalog and he Service Manual available and some parts. Give me a call at 405-503-4686, Don Nieser, Commodore Aerospace Corp or e-mail: nieser.02.337parts@juno.com.

Nav-O-Matic
 

I have become intimate with the navomatic autopilot in my T337D over the years, and have the full install and maintenance manual. AND I'm a nerd. Let me know if I can help.

The switch (GYRO ON/OFF) on the back of the control head
should be OPEN, only for setting the zero / null positions on the servos
to temporarily disconnect 'error' signal from the gyros,
then for normal operation, CLOSED
to re-connect the error signals coming from the DG heading gyro and horizon.

If you need some unofficial ways to zero out the servos, let me know.... :)

tips
 

any tips or hints are always appreciated. if you don't feel comfortable posting them, drop me an email at rmorris@agsi.us

on your post above, you mention OPEN and CLOSED...which one is on and which one is off (the two positions on the switch :) ?