S-TEC options

[Pat Rolfes]

After 3rd trip to avionics to try and fix my VFR only 400a autopilot, I'm throwing in the towel.
I have never had it as a "coupled" autopilot. It was always hand flown using DG knob and alt. hold or control wheel altitude climb/descent.
With that history, I am having trouble determining my needs vs. expenses between S-TEC 30 or 55.
Anyone out there with pro or con arguments for either.both?
Thanks,
Pat

[skymaster]

After 3 years without a/p our 73 p now has its s-tec 65. The previous owner 's autopilot was sent out and lost. Finally recovered pieces. It's a joy having a coupled rate based a/p. Now my hand flying skills are suffering the effect of good autlo-pilot. However spifr skills have never been better. J

[Guy Paris]

Pat,
I have a 77 G with the 400A. Early on when I first got the bird which was (10) + years ago the A/P would not couple to the ILS. I took it to an avionics shop in NH. An old timer since retired, repaired it and it has worked quite well over the years and will do a reasonable coupled approach. There will probably be lots of pro and con over the 400’s. The shop that you deal with, do they have an old timer or someone that KNOWS the 400? Maybe do a search and see if you can find an old timer or someone who knows the 400’s. In my neck of the woods, NH./MA. There is a shop on the Cape (HYA) Griffin Avionics that still works on them, at least the last I checked or needed work done which was (6) years ago. At that time the trim motor was changed out. I sure would like one with all the niceties however it will have to break real bad for me to do that. Hope she’s not listening, wouldn’t want to jinks it. Guy, the old 72 driver…

[MikeZ]

I replaced the 400A with an S-tec 55 several years ago and couldn't be more satisfied. The 400A was always breaking down and doing some scary things on its own. The 55 has been reliable. I don't have any comment on the 30. It's worth the expense to put in a reliable autopilot. You'll save money and aggravation and enjoy your plane more.

[Ernie Martin]

Let me agree on one point but suggest some disagreement on another. The agreement is that it's worth the expense to put in a reliable autopilot.

On the other hand, my impression from my own aircraft and the comments of other Skymaster owners is that the Cessna units (e.g, 400A) are reliable. Because of their age, there may come a time when the Cessna units may start misbehaving, but most of the time is the capacitors leaking. After 30+ years, seems understandable to me. Typically, a change of capacitors does the trick, and there are enough shops around still Cessna-savvy to do the job.

Do other Skymaster owners share this view or am I wrong?

Ernie

[Bob Cook]

400 AP is a good autopilot! like everything else you do need to pay some attention to it if it is going to satisfy your needs.

There are still lots of places that service them. I would recommend fixing it before investing in a lot of money. It is NOT rate based but a true two axis autopilot that will correct the heading before a rate of change is detected.

90% of the time it is the servo or power supply that is giving problems.

Mine is fully coupled including a 90b interface. Works flawlessly!

fyi

Bob

[Mitch Taylor]

One other consideration: I've heard that S-Tec has problems with the STC for Skymasters. I think is has to do with the servo on the ailerons, but I don't remember for sure. You should check with them before you get too far.

[Dale Campbell]

I have the 400-A in my 337H. I have had so many falures in the last 3 years, that it has been in the shop more than in my panel.
I had pin shear in servo twice. Had 3 differant problems with Mode
Selector, broken wires in control yoke switch, computer had 2 transistors short out at 2 differant times. Short in harness in instrument panel. Also controller in center console failed. That all cost me $7000.00 + dollars. It works great now but for how long. Had I known what I was going to pay 2 years ago. I would have put my money into a new S-TEC.

[MikeZ]

Dale's comment reflects my own. It's all a matter of cost and reliability for your intended use. If the 400 autopilot is reliable enough for you, fix it and keep it. If it is not, change it. Simple. I fly enough hard IFR to want absolute reliability. I also had recurring hard wingovers. Kept me on my toes but the passengers didn't quite understand.