Dummy guide needed: s-tec 40/50 autopilot

LifeAsBen

LifeAsBen

Pre-Flight
Joined
Aug 1, 2016
Messages
54
Display Name
Display name:
LifeAsBen
I feel like a total newb, ok I sort of am. But I did just pass my IR checkride so I'm not a total fool. Anyways...I joined a flying club and the C172 has an s-tec 40/50 autopilot. So naturally I checked out the POH for the AP but it is not intuitive. I need an Idiots Guide to how to use this AP! Can anyone out there explain this thing in plain english ?

Here's the POH for the s-tec 40/50: http://genesys-aerosystems.com/sites/default/files/files/System Forty_Fifty.pdf
 
First off, which one is it a 40 or 50? Does it have the ALT button?

Anyhow, before takeoff, follow the preflight checks in the manual. Doing so SHOULD give you good hint as to the operation.

As with the other S-TEC autopilots it is rate based off the turn coordinator.

Simplest is to just push the big knob. It will hold everything straight and level at the point you engage it. You can do turns with the knob.

For HDG mode, dial the bug up on the DG/HSI to where you want and push the big knob again, it should follow the BUG. For NAV mode, set up your radio and primarily indicator (HSI or CDI) and then press NAV.

If you have a 50, pressing ALT will hold the altitude. If you don't have electric trim, it will beep at you and flash the UP/DOWN lights to tell you it wants to be trimmed in that direction. If you do have electric trim, it will drive the trim as needed itself.
 
Get an instructor and get checked out with it. I fly a Cirrus with a 55, no alt preset but alt hold. Every once in a while it does some funky stuff, but it is 14 years old and needs some love. You have to keep your eye on George.
 
Yea doesn't get much more straight forward. Like Ron said, put it in test mode before departure, then to on. Do what Ron said except I never use the Nav mode, I always keep it in Apr mode as that keeps it more centered on the CDI.
 
youtube? here, this guy just barely kinda sorta knows how to use the hdg bug

 
I have a 55X, and it takes a while to get to the point (especially on approaches) that you aren't hovering over the red button all the time when you get the "what the f is this thing doing?" feeling. That's why I practice all my approaches twice: one with the AP, one without.

Anyhow for STB and HDG mode (possibly with the addition of ALT) the 40/50 is pretty straight forward "one button" operation.

I did have one fun experience with the autopilot. I had a long taxi at IAD from the FBO (Landmark) to 30. Taking off on 30, I thought I had a little touch of wake turbulance but nothing I couldn't handle. I turned on course and kicked on the autopilot. Soon I note the autopilot is sort of making s-turns across the course. Very strange. I hit the red button and felt the thing turn hard left. Turns out I had run one of the tip tanks dry on the ground with the other full.
 
I agree with the sentiment to get checked out with an instructor. Or at least read up on it and fly it with another (long-time) owner from the club. Nothing beats hands on training. Of course the first thing to learn is how to disengage the A/P in case it goes bonkers. There are usually 2-3 ways, learn them all, memorize them. Make sure you can do it in the dark, with your eyes closed, upside down, on fire.

My stab at a simple explanation (disclaimer, I am not a CFI):
- The 50 model has an altitude hold over the 40 model. It does not use trim but tugs on the elevator cables instead. It will light up one of the trim LEDs if it needs help trimming the elevator.
- The STB light does NOT mean "standby". Careful. It means "stabilize", as in "wing leveler". IMHO, it is poor wording but I got used to it. You enable/disable STB mode by pushing the ON/OFF button.
- The knob is useful for doing turns with the A/P but I never used it so far. The knob also has a push button which enables the HDG mode. Intuitive, huh? :)
- The NAV mode is enabled by the NAV button (if you didn't guess already). It will fly whatever nav signal you're feeding it (LOC, GPS), check your panel.
- I have never used the APR or REV buttons. I would like to try them out one day, in VMC, to see whether I can for example really track the localizer outbound.

I sure hope you can find some useful videos on YT, they should help.
 
I have a 60-2....it's simple, cept when you want to couple the glide slope. There are a few steps before it works the way you think it should.
 
While the alt feature pulls on the elevator cables it needs the aircraft to be reasonably trimmed. If you have electric trim connected, it will do this itself. If you don't, it beeps at you and tells you via the lights which way to trim it.

The KNOB toggles between STB and HDG for each push (provided you have a heading bug hooked up).

The APR button is pretty much the same as NAV except a bit more sensitive (on other STEC units, it allows the GS intercept to happen if an ALT mode is also selected).
The REV button causes the autopilot to go the opposite way of the needle. I think on this unit it only works if also in APR mode. You can test it by dialing up a NAV station and turning the OBS/Course Arrow left and right. In NAV or APR it should fly towards the needle. If you have REV on, it should work backwards. This is for flying outbound on the front course or inbound on the back course. Note that even if you have an HSI, you need to set this properly.

The 55X puts the NAV and REV testing into the pre-flight test scripts. The 40/50 apparently only does HDG BUG tracking.
 
flyingron said:
If you have a 50, pressing ALT will hold the altitude. If you don't have electric trim, it will beep at you and flash the UP/DOWN lights to tell you it wants to be trimmed in that direction. If you do have electric trim, it will drive the trim as needed itself.
Click to expand...

Close, with one caveat: If you have *S-TEC's* electric trim, it will trim itself. One of our club planes has the S-TEC 60-2, but still has the original Cessna electric trim. They do not talk... So the autopilot still asks for trim as if you had manual trim, and you can trim it with the other-brand electric trim switch on the yoke. If you have the S-TEC trim, it works as Ron described (which is much nicer).
 
Also, they only ask for elevator trim, will not do aileron trim.
 
Grum.Man said:
Also, they only ask for elevator trim, will not do aileron trim.
Click to expand...
Correct. They don't need (or request) aileron trim. Which is handy because to adjust my aileron trim, I'd have to climb out on the wing.
 
Get a sharpie fine point. Go fly and start pushing buttons. When you figure out what they do write a note on the panel with the sharpie.

Temporary notes should be written with grease pencil on the windows. (I actually do this when single pilot)


While I am joking I have seen this done before.
 
I once jumped from a plane that had all the switches, etc... labeled with an old style Dymo gun. Particularly amusing was the one marked "PEETOT HEAT"
 
flyingron said:
Correct. They don't need (or request) aileron trim. Which is handy because to adjust my aileron trim, I'd have to climb out on the wing.
Click to expand...

Your airplane may not need it but mine does. I know it needs trim when the wings start wagging from th servo trying to hold it level. Most of the time I wait till trimmed to turn it on.
 
Just wanted to say thanks to everyone for the replies, all very helpful. This community is the best!
 
LifeAsBen said:
Just wanted to say thanks to everyone for the replies, all very helpful. This community is the best!
Click to expand...
You obviously haven't been here long enough. Give it time, you will change your opinion! :D

Nah, glad you got good feedback.
So which model specifically do you have? 40 or 50? (sorry, I didn't find an answer above)
 
flyingron said:
First off, which one is it a 40 or 50? Does it have the ALT button?

Anyhow, before takeoff, follow the preflight checks in the manual. Doing so SHOULD give you good hint as to the operation.

As with the other S-TEC autopilots it is rate based off the turn coordinator.

Simplest is to just push the big knob. It will hold everything straight and level at the point you engage it. You can do turns with the knob.

For HDG mode, dial the bug up on the DG/HSI to where you want and push the big knob again, it should follow the BUG. For NAV mode, set up your radio and primarily indicator (HSI or CDI) and then press NAV.

If you have a 50, pressing ALT will hold the altitude. If you don't have electric trim, it will beep at you and flash the UP/DOWN lights to tell you it wants to be trimmed in that direction. If you do have electric trim, it will drive the trim as needed itself.
Click to expand...
The STEC-50 like the STEC-30 has altitude hold. Both are a basic 2 axis autopilot that does a decent job tracking a VOR or GPS course. However, it is not very aggressive in turns so if you have sharp angles between waypoints or fly a procedure turn, more than likely you will fly though to desired change in tracking or heading. To compensate I use the heading mode or ST mode to turn and then engage NAV or HDG for my final approach course. Turns are also lazy as mention before even if your Navigator or Apsen unit has a GPSS function. With that I leave the unit on HDG mode, it will tack just like the HDG bug and makes switching between HDG and GPS with the touch of the GPSS button.
 
Grum.Man said:
Yea doesn't get much more straight forward. Like Ron said, put it in test mode before departure, then to on. Do what Ron said except I never use the Nav mode, I always keep it in Apr mode as that keeps it more centered on the CDI.
Click to expand...
Is it supposed to work that way, or is Nav not functioning properly?
 
MauleSkinner said:
Is it supposed to work that way, or is Nav not functioning properly?
Click to expand...
Nav mode allows more deviation from the set course. Mine doesn’t have GPS steering so when you combine that with the speed of my plane it causes it to chase the Cdi too much unless it’s a calm day. A normal plane probably wouldn’t have an issue.
 
You must log in or register to reply here.
Back
Top