337 autopilots

[N5ZX]

I have an S-Tec 60-2 in my '77 and it works well...if ya dont mind a little porpoiseing at cruise. I think they run about $10k off the shelf.,,,,installation is, of course, the big bugger.

But BEWARE of the temptation of "affordable" autopilots available on ebay, etc.

I have read in many MANY articles that S-TEC will not support ANY autopilot other than that for which it was purchased NEW. It doesnt matter if you want to install a yellow-tagged autopilot in the same year, and model, S-TEC wont have anything to do with it once it is removed from the aircraft in which it was originally installed.

As always, I could be wrong....it's been known to happen.

But I've read it in a number of independant, "reputable" resources.

Caveat Emptor!!!

Cole

[CO_Skymaster]

I've heard that before about S-tec. They tend not to hold a steady altitude. Is there a reason for that and are the original autopilots better at altitude hold and tracking course?

Karl

[Rick Gardner]

I have an STEC 55X in our 76 model and it reallly does not work well at all. I have spent thousands to have the computer, transducer etc. sent to STEC. We had a King KAP140 in out Cessna206 and it worked really well. Now, I am not trying to promote one versus the other but my impression after having both is that the STEC does very poorly capturing laterally and vertically. As usual, the avionics shop says it the autopilot, STEC says its the installation and I say......

Now STEC admits there may be an issue wih the servos and that there is a procedure to clean out the servos.....

Anyone else have this issue?

[Roger]

The only problem I have with my plane is my piece of crap stec 60-2. It is like riding a porpoise at cruise, plus I can't get my altitude pre-select to capture any input data. I typically don't use altitude hold. It works great on the Bug, needle and GPS tracking (GPSS Roll Stearing) and if trimmed corrrectly the plane itself holds altitude, bit the minuite I click on Altitude Hold it start to porpoise. Any help would be appreciated.

[tropical]

Originally Posted by Roger

The only problem I have with my plane is my piece of crap stec 60-2. It is like riding a porpoise at cruise, plus I can't get my altitude pre-select to capture any input data. I typically don't use altitude hold. It works great on the Bug, needle and GPS tracking (GPSS Roll Stearing) and if trimmed corrrectly the plane itself holds altitude, bit the minuite I click on Altitude Hold it start to porpoise. Any help would be appreciated.

Sounds like you have moisture in the static line to the autopilot computer. Dry that out and the problem will go away.

[skymstr02]

Originally Posted by Roger

The only problem I have with my plane is my piece of crap stec 60-2. It is like riding a porpoise at cruise, plus I can't get my altitude pre-select to capture any input data. I typically don't use altitude hold. It works great on the Bug, needle and GPS tracking (GPSS Roll Stearing) and if trimmed corrrectly the plane itself holds altitude, bit the minuite I click on Altitude Hold it start to porpoise. Any help would be appreciated.

Is the bridle cable tension on the pitch servo tight enough? Sometimes low cable tension will create the porpose effect.

[Rick Gardner]

Static lines checked, servo motor removed and set to factory torque settings, rigging checked for proper tensions.

[Roger]

My IA advised me to try flying the autopilot with the interior standby static open. I flew first with it closed and the 60-2 hunted 100' +/-, then I closed it and after re-establishing a set altitude, it tracked +/- 20'. Much, much better. So I guess the problem is in the static system, water, etc..