S-TEC 60-2 w/GPSS and LPV Approaches?

[kent@williamkent.com]

I have an S-TEC 60-2 autopilot with Altitude Preselect and GPSS hooked up to a Garmin 530W.

My question is - - can this autopilot fly a GPS Waas approach, an LPV approach, and track the GP?

I can't get it to do it, it flies the ILS GP perfectly but I can't get it to fly the GP on the GPS Waas approach. Am I doing something wrong or does it simply not have the capability?

If it can fly the GP on an LPV approach, what mode do I set the autopilot on as I activate the approach? What mode is the GPSS to be set on?

Any help will be much appreciated.

 

[SCCutler]

Counselor:

I believe that, properly configured, your 60-2 should be able to intercept and fly a GPS glide path, but I'll defer the estimable John Collins, whose knowledge in this arena is unmatched.

And, by the way, welcome to PoA! We like lawyers here!

 

[poadeleted20]

God, you lawyers, sucking up to each other like that. Where's that barfing smiley when I need it...

First, the 60-2 doesn't have intergral GPSS (strictly CDI needle-driven for GPS tracking unless you have GPSS). If you don't have GPSS, you have to get it to intercept the final approach course in NAV mode and then step to APR mode far enough before GS intercept that it thinks it's flying an ILS.

If you're using GPSS, then it's getting its feed through the HDG input, and it will not capture GS in HDG mode. That means you need to get it on the final approach course using GPSS and then shift from HDG to NAV and then APR far enough before GS intercept that it thinks it's flying an ILS.

 

[John Collins]

I have an S-TEC 60-2 autopilot with Altitude Preselect and GPSS hooked up to a Garmin 530W.

My question is - - can this autopilot fly a GPS Waas approach, an LPV approach, and track the GP?

I can't get it to do it, it flies the ILS GP perfectly but I can't get it to fly the GP on the GPS Waas approach. Am I doing something wrong or does it simply not have the capability?

If it can fly the GP on an LPV approach, what mode do I set the autopilot on as I activate the approach? What mode is the GPSS to be set on?

Any help will be much appreciated.

Kent,

I have the same combination of equipment in my Bonanza except for the altitude preselect. The fact that you can fly a coupled ILS, but not a LPV suggests either an operator error or a wiring error.

I generally will use HDG mode and ALT hold mode when being vectored to the final and on the final intercept vector will activate selected heading intercept on the 60-2 by pressing both HDG and NAV simultaneously.

If I am flying the complete approach using my own navigation, I will have the autopilot in both heading and altitude as before, but my GPSS will have GPSS selected. Once I am aligned with the final approach course, I will select NAV mode on the 60-2. Once you are out of HDG mode, the GPSS is irrelevant. The autopilot should automatically switch to APR mode and track the glidepath.

The wiring error possibility is that the wrong signal was interconnected to the autopilot. The autopilot has an input named "ILS Energize" and the 530W has an output of the same name on P5006 - pin 29. If these two pins are interconnected, you will be able to track an ILS GS but not a LPV GP. The correct 530W signal to wire to the autopilot is "ILS/GPS Approach" P5001 - pin 14. If this is your situation, have the shop that installed the 530W fix it as a warranty fix. The install wiring diagrams are clear on this point, but many older know it all installers "don't need to read no FXXXING manuals".:wink2:

 

[TMetzinger]

Kent,

I have the same combination of equipment in my Bonanza except for the altitude preselect. The fact that you can fly a coupled ILS, but not a LPV suggests either an operator error or a wiring error.

I generally will use HDG mode and ALT hold mode when being vectored to the final and on the final intercept vector will activate selected heading intercept on the 60-2 by pressing both HDG and NAV simultaneously.

If I am flying the complete approach using my own navigation, I will have the autopilot in both heading and altitude as before, but my GPSS will have GPSS selected. Once I am aligned with the final approach course, I will select NAV mode on the 60-2. Once you are out of HDG mode, the GPSS is irrelevant. The autopilot should automatically switch to APR mode and track the glidepath.

The wiring error possibility is that the wrong signal was interconnected to the autopilot. The autopilot has an input named "ILS Energize" and the 530W has an output of the same name on P5006 - pin 29. If these two pins are interconnected, you will be able to track an ILS GS but not a LPV GP. The correct 530W signal to wire to the autopilot is "ILS/GPS Approach" P5001 - pin 14. If this is your situation, have the shop that installed the 530W fix it as a warranty fix. The install wiring diagrams are clear on this point, but many older know it all installers "don't need to read no FXXXING manuals".:wink2:

John - the ILS energize input you refer to - is that the input that tells the autopilot "Hey this is a localizer (or other approach precision input) and you should switch to APR mode"?

BTW, I really appreciate your participation - I've learned an awful lot of useful details from your posts.

 

[John Collins]

John - the ILS energize input you refer to - is that the input that tells the autopilot "Hey this is a localizer (or other approach precision input) and you should switch to APR mode"?

BTW, I really appreciate your participation - I've learned an awful lot of useful details from your posts.

Yes, the input to the autopilot is to tell the autopilot when a localizer is tuned by a Nav receiver. That signal in combination with the lack of flags for horizontal and vertical CDI, tell the autopilot to look for a GS. Since the ILS Energize predates the invention of WAAS GPS with vertical, the new signal ILS/GPS Approach replaces the older ILS Energize. ILS/GPS Approach is active under two conditions: 1) When the CDI has been selected to VLOC, it acts the same as ILS Energize; and 2) When the CDI has been selected to GPS and an approach has been activated, it simulates ILS Energize to the autopilot so that it will enable the intercept and track of the glidepath function. The autopilot doesn't know the difference.

 

[kent@williamkent.com]

Thanks to everyone who responded. I have cut and pasted your responses into an email and emailed them to the avionics shop that is looking at it for me.

They were not sure that the S-TEC 60-2 could fly the glide path on an LPV approach - they knew an S-TEC 55x could but were unsure whether the 60-2 could or not. They think it is wired right, so it sounds like I am not pushing the buttons right.

What can you expect? I am an appeals lawyer, I am old, I majored in German Literature in college, and my wife says I have no common sense (and she would know).

 

[John Collins]

Thanks to everyone who responded. I have cut and pasted your responses into an email and emailed them to the avionics shop that is looking at it for me.

They were not sure that the S-TEC 60-2 could fly the glide path on an LPV approach - they knew an S-TEC 55x could but were unsure whether the 60-2 could or not. They think it is wired right, so it sounds like I am not pushing the buttons right.

What can you expect? I am an appeals lawyer, I am old, I majored in German Literature in college, and my wife says I have no common sense (and she would know).

It would be truly sad if the avionics shop doesn't know if your autopilot could intercept and track a LPV glidepath. It suggests that they did not test the autopilot or check the boxes properly on the AFMS that is required for your 530W installation. Hopefully, you are misquoting your shop.

Did they provide you with an AFMS for the 530W install? If not, then your installation is not legal for IFR. I have attached a copy below, it is for a 400W series but change the references to 500W and it is the same. Note that the installer has to check the boxes on page 9 and 13.

View attachment GNS400W Rev A AFMSforSWVer3.0_190-00356-03_.pdf

 

[SCCutler]

See - toldja!