Centering your Navomatic autopilot

[n86121]

It sounds like to fly level w autopilot,
you are offsetting two errors,
using the aircraft trim to balance an offset in the autopilot elevator.

Thus, when you turn on altitude hold,
it tries to go 'back' to where it wants to be,
which puts you into a climb or dive.

I would re-zero the elevator servo and that might straighten it all out.

If at some point the cables were re-rigged, even a little bit,
that would introduce an offset into the autopilot

[Skymaster337B]

Any leveling suggestions for the Navomatic 300?

[n86121]

From a quick glance, the same process should apply.

Fly, determine and mark where the aircraft controls result in straight and level flight.

Then, on the ground,
Secure the controls in that same straight-and-level position

Disable aqny gyro correction signals with that small switch on back of head
(The autopilot's head, not your own).

Split the servo's in half, set the autopilot to center
and let the servos 'center' as well.

Then put them back together!

Presto, when the servos are centered, the controls will be centered.

Starting looking at the schematics to decode the adjustments,
but I spent the day working on a 100 meg statistical meteorological spreadsheet,
while also dealing with Federal agencies.

So I think I need to start drinking now ...

[hharney]

Elevator actuator split for centering system

[rmorris]

Originally Posted by hharney

Elevator actuator split for centering system

Herb...From the pic, it looks like yu tried the split servo suggestion. Did it work out?

I have a roll servo, just overhauled by a/p central in OK. Overall a/p sys has not been used for years, and just now hooked up to the Dual G5s, via GAD29B. on the ground, it appears the wing leveler mode allow the yoke yo more or less center, roll right, roll left, etc. The hdg bug in air does appear to get it in a direction, but seems I have to have it offset to go where I want...ie I want to track 320, I might need to turn heading bug to 327. I'm getting basic funct now, or as AT&T commercials say, "it's just OK".
Since I just got the servo back from o/h, leery of splitting in half, but seems that this "centering method" Dave suggests to be plane specific (ie fly your plane in straight and level flight and mark controls) might be worthwhile.

PS. Flying into OSH todday with Cessnas 2 Osh formation flight, and will be parked at Cessna Base Camp in North40 camping area. CFI Volunteering in the Pilot Proficiency Center area Mon afternoon shoft. Stop by one of those areas to say hi, if you hit OSH this year.