Autopilot

[Ernie Martin]

The last few messages in the thread "Turbo Trouble" has shifted to autopilot issues. Some of you who don't have turbos may not be reading this thread, so I wanted to mention it.

BTW, Pete Somers is knowledgeable on the Cessna/ARC autopilots and will be at the Lucaya fly-in. And remember that you don't need to fly your Skymaster to the meeting, since there is good commercial airline service into Freeport. Or you might fly into Florida, since we expect to be able to arrange for you to hitch a ride on one of the Skymasters.

Ernie
Webmaster

[Pete Somers]

Thanks Ernie.

I will bring all the service parts manuals and setup for the ARC 400 and IFCS, so i look forward to some questions regarding any problems with the system.

See ya in Lucaya!

Pete

[Ernie Martin]

Good show.

[Skymaster337B]

Pete, do you know much about the navomatic? I have one on a 67' Skymaster. It's a wing leveler/heading hold/supposedly course tracking.

My problem is that, it seems to work when I'm flying straight and level for a while, on a smooth air day. But otherwise the wings turn too much, and over banks before correcting. I've adjusted the gain, but like I said it seems to work well when I've been flying straight and level for at least 10-15 mins.

I hear there may be a simple capacitor to replace and it should work perfect.

Any info to share?

Rob

[Pete Somers]

Hi Rob

This sounds like the gyro is running slow or binding, has the gyro been replaced or overhauled at any time?
Adjusting the roll gain is a can only be done with a test rig or a break out box.

Try taking the gyro out and with it connected run the autopilot and bank the gyro left and right and see how sensetive the autopilot is to the movement of the gyro, it should be quite sensetive.

Or the bank angle adjustment is out, again needs a break out box to set it up.

Let me know how you get on.

Regards
Pete

[basloane]

Good Morning all.

It seems that my autopilot needs some adjustments, and I need a service manual for a Cessna 400A Autopilot with Altitude Hold, Nav and Glideslope coupling.

Does anybody know where I can find one, or alternatively, does anybody have a scanned copy they can send to me?

Best Regards,.......Barry Sloane,..N187 - 1975 T337G

[Pete Somers]

Hi Barry
What is wrong with the autopilot alt hold?
Can I help in any way.

Pete

[WebMaster]

Esco has manuals for the auto pilot.

[Dave Underwood]

Barry, I will check as I may have a copy.

Can I suggest you have an email dialogue with Peter as he is a great resource, very knowledgable and not that far from you in relative terms.

Based on several conversations with Peter, you really need a breakout box to set the system up.

Drop me an email at dcunder@aol.com.

Regards - Dave

[Pete Somers]

Thanks Dave.

Barry I have all the manuals for the 400A and 400IFCS. But to adjust these autopilots as Dave says you will need a breakout box, which i also have.

Pete

[basloane]

My sincerest apologies to Pete, Larry and Dave.

I posted my message regarding autopilots in October, but for some reason the system did not notify me that you had been responding to, and trying to help, me. Also, at the time, it slipped my mind that I had even posted the message ( that I can blame on age! ) I feel very bad about this,....again, my sincerest apologies to all.

Ok,....now to the problem....

On the ground, the wing levelling, heading hold and nav tracking functions seem to work very well. The trim wheel however, continually rolls forward, hits the limit of travel, and then the motor continues to try and roll the thumb wheel forward. If I give the control column a quick "shove" forward or backward, the wheel stops and the system seems to become stable.

All three switches for initial engagement, nav tracking and altitude hold engage very easily on the ground.

In the air, I set the aircraft up for level flight, trim it well and then try to engage the autopilot. It resists engagement and I must repeatedly push the rocker switches until it finally engages, then the trim thumbwheel starts rolling forward. The wheel reaches the limit of its travel and then the motor continues to try and roll the thumbwheel forward.

All of these "goings on" do not affect the trim, attitude or flight of the aircraft.

I have replaced the Artificial Horizon and Directional Gyro, and had all the boxes removed and sent to Autopilots Central for testing.

I can't think of anything else. Looking for ideas.

Best Regards,.....Barry Sloane

[Pete Somers]

Hello Barry
No problem just thought you maybe away or something.

Once you get the autopilot engaged, not ALT HOLD what rate of climb or decent do you get, should be about 700 ft min climb max and about 1200 ft min decent.

If you have had all the gyros and autopilot away for checking it sounds like the pitch servo needs recentering.

What is happening is in the climb the followup system in the pitch servo is going out of range, so the gyro signal cannot sync with the pitch attitude of the aircraft so the pitch wheel goes up or down to the stop and the motor keep running. If you lower the nose by pushing forward on the column you will find that it will engage at a low rate of climb.

You need to reset the pitch servo. I can copy this out of the manual but it is a tricky job as the elevator has to be set to the right position for neutral, have you somebody out there that can do this?

Let me know

Regards
Pete

[basloane]

Hi Peter

It was some time ago that I tried to engage the autopilot in a climb, and I cannot exactly remember what sort of numbers I was getting.

Yes I do have someone who can help me with this. I ( sort of ) did an exercise like this a coulple of years ago, but I have forgotten what exactly we did.

It sounds like you have a service manual. lf you are able to scan the relevant sections and email them to me, that would be fantastic.

Many thanks for your assistance.

Regards,.......Barry

[Pete Somers]

Barry

Let me know your email address nad i will scan them for you.

mine is pete@somers40.freeserve.co.uk.

Cheers
Pete

[basloane]

Hi Peter

My email address is bsloane@qatargas.com.qa

Cheers,......Barry