Mooney 20J with Century III and Electric Trim

[Lwebb1952]

I have a 78 Mooney 20J with a Century III autopilot and electric trim.  There is currently a problem with the pitch and the pitch and altitude hold, neither seem to work right in the air.  But, separate from the problem, neither the Century III pitch or the altitude hold seem to work unless the electric trim switch is turned on.  Is this correct, or should the Century III pitch functions work independent of the electric trim.  Does the electric trim and the pitch servos work in conjunction when the autopilot is on?  The electric trim switch in my case is on the pilot yoke, forward to trim nose down, back to trim nose up, and push down to disengage the autopilot.

Thanks.

[gsxrpilot]

I would expect the electric trim to have to be on for the autopilot to function.  I have a KFC150 and it requires the electric trim on.

[Oldguy]

Not sure about the C III, but every King AP I have ever seen requires the electric trim switch to be on, but it is a panel switch. I can turn the panel switch off, but my AP will not pass its test. I can still fly by hand without a problem, adjust manually by spinning the trim wheel, but the trim switch on the yoke will have no effect.

In all likelihood, it is working as designed, but there should be documentation in your POH detailing everything for you.

Or, as another option, you can call the factory in Mineral Wells, Texas and get their opinion.

[copierdynamics]

Just as a side note the pins in the connectors of the Century autopilot loosen and cause all sorts of intermittent problems.Tighten up the female ends before throwing money at it.

[Lwebb1952]

i heard a lot about these pins.  What is the recommendation of tightening the female pins?

[Lwebb1952]

On ‎6‎/‎14‎/‎2017 at 1:33 PM, Oldguy said:

Not sure about the C III, but every King AP I have ever seen requires the electric trim switch to be on, but it is a panel switch. I can turn the panel switch off, but my AP will not pass its test. I can still fly by hand without a problem, adjust manually by spinning the trim wheel, but the trim switch on the yoke will have no effect.

In all likelihood, it is working as designed, but there should be documentation in your POH detailing everything for you.

Or, as another option, you can call the factory in Mineral Wells, Texas and get their opinion.

The Century manual is not straight forward on this subject but the way it the system acts makes sense. Thanks.  More troubleshooting to do on the pitch and altitude hold.