STEC-60 Frustration

[Joe Larussa]

So I just had my 530 upgraded to Wass. After a few attempts I figured out how to get the autopilot to follow the glide slope. When doing an Lnav approach the accuracy seems amazing. I'm using Gpss steering. It looks like when shooting an LPV  you have to switch to Nav mode on the auto pilot to get the vertical guidance. I do believe that turns the Gpss off. When I shoot an ILS the accuracy is pretty good but not as good as the Gpss action. Seems to me when I push he Nav mode it just isn't as good including when I'm using the GPS. Thoughts?

[Marauder]

Joe -- the reason you are seeing this is because the GPS signal is digital and much more stable than the ILS. I don't know what you are using for GPSS. I am using an Aspen PFD and it will stay engaged when in Nav mode.

If you watch your STEC couple on an approach, you will see a "soft" indicator come up. This is to address the variability of the needle swings of an ILS or VOR approach. When flying the LPV approach, I'm willing to bet it is not needed.

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[Joe Larussa]

15 minutes ago, Marauder said:

Joe -- the reason you are seeing this is because the GPS signal is digital and much more stable than the ILS. I don't know what you are using for GPSS. I am using an Aspen PFD and it will stay engaged when in Nav mode.

If you watch your STEC couple on an approach, you will see a "soft" indicator come up. This is to address the variability of the needle swings of an ILS or VOR approach. When flying the LPV approach, I'm willing to bet it is not needed.

Sent from my iPad using Tapatalk

 

[Joe Larussa]

Not sure what I'm using for Gpss. It's a new to me switch on the panel. Seems like whenever I hit the Nav button it's just kind of ok not great. I thought when I upgraded to Wass it would be amazing with the autopilot but not so much. The Nav side whether it's GPS or ILS is not great. I wonder if I'm doing something wrong.

[Marauder]

Not sure what I'm using for Gpss. It's a new to me switch on the panel. Seems like whenever I hit the Nav button it's just kind of ok not great. I thought when I upgraded to Wass it would be amazing with the autopilot but not so much. The Nav side whether it's GPS or ILS is not great. I wonder if I'm doing something wrong.

It could be the GPSS unit that may be the difference. My Aspen GPSS is extremely smooth enroute and does an excellent job on approaches.

Not sure if you ever videotaped your approaches. If so, it is a lot easier to understand what is going on when you can see what it is doing.

[Joe Larussa]

14 minutes ago, Marauder said:

It could be the GPSS unit that may be the difference. My Aspen GPSS is extremely smooth enroute and does an excellent job on approaches.

Not sure if you ever videotaped your approaches. If so, it is a lot easier to understand what is going on when you can see what it is doing.

It seems like soon as I hit the Nav switch it just kind of sucks no matter what the deal is. Gpss and And heading on the Stec and its crazy good.

[Marauder]

14 minutes ago, Marauder said: It could be the GPSS unit that may be the difference. My Aspen GPSS is extremely smooth enroute and does an excellent job on approaches.

Not sure if you ever videotaped your approaches. If so, it is a lot easier to understand what is going on when you can see what it is doing.

It seems like soon as I hit the Nav switch it just kind of sucks no matter what the deal is. Gpss and And heading on the Stec and its crazy good.

The Nav mode should provide a less aggressive (but still accurate) tracking. I would make sure the preflight tests all pass and that the correct indicators are on during the capture part of the approach. The only time I have seen some sloppiness has been in strong gusty winds. Otherwise, the tracking is really decent. It feels like it is on rails.

Before I spent a penny on having someone look at it, find someone who has flown with one to see what they think.

Also let us know what kind of GPSS is driving the AP. Maybe someone will have experience with it.

[Joe Larussa]

19 hours ago, Marauder said:

The Nav mode should provide a less aggressive (but still accurate) tracking. I would make sure the preflight tests all pass and that the correct indicators are on during the capture part of the approach. The only time I have seen some sloppiness has been in strong gusty winds. Otherwise, the tracking is really decent. It feels like it is on rails.

Before I spent a penny on having someone look at it, find someone who has flown with one to see what they think.

Also let us know what kind of GPSS is driving the AP. Maybe someone will have experience with it.

I talked to the tech support guy at S-tech today. He said to check the voltage at the servo motors. Sounds like the Gpss is disengaged when you push the Nav button. When using Gpss he said something about the voltage being higher than Nav mode so better results. My autopilot is twelve years old so maybe it needs a little money thrown at it.

[Marauder]

19 hours ago, Marauder said: The Nav mode should provide a less aggressive (but still accurate) tracking. I would make sure the preflight tests all pass and that the correct indicators are on during the capture part of the approach. The only time I have seen some sloppiness has been in strong gusty winds. Otherwise, the tracking is really decent. It feels like it is on rails.

Before I spent a penny on having someone look at it, find someone who has flown with one to see what they think.

Also let us know what kind of GPSS is driving the AP. Maybe someone will have experience with it.

I talked to the tech support guy at S-tech today. He said to check the voltage at the servo motors. Sounds like the Gpss is disengaged when you push the Nav button. When using Gpss he said something about the voltage being higher than Nav mode so better results. My autopilot is twelve years old so maybe it needs a little money thrown at it.

Let us know the resolution. Too bad you aren't closer. I could tell you on one approach if it is working correctly or not.

[carusoam]

I wrote this a day ago thinking an answer may come about.  It didn't, so let me share what I was thinking. See if it helps.

1) If the GPSS is hooked up in the most basic way, it may only be active with the AP in heading mode.

2) The APCH mode for my AP (on the KAP150) changes the tuning function for tighter control on the approach.  The cost is a less comfortable ride if it were used during cruise.

3) do you use the heading mode to navigate through the flight then switch to approach mode prior to  beginning the procedure?

 

Question: Do you have an approach mode that is selecting a finer set of tuning Parameters?

follow-up: Have you built a chart of what is connected with all the various switch combinations?

The GPSS device is calculating many waypoints and delivering them to the GPS.  The AP is controlling the plane to follow the waypoints.  The AP has different modes that effect how the plane follows the way-points.

the person who has installed the GPSS and connected it to the AP probably has this chart.

Trying to figure this out by test flying it endlessly seams a bit rare.

The differences in analog vs digital nav, GPS vs VOR, give uncomfortable feelings until they get better understood in one's plane.

Doing this as part of an approach leaves me uneasy thinking something may not be working correctly.  Hard to fly an approach in IMC without knowing everything is working.

Is there a way to get trained on your hardware's specific operations?

If self training on your hardware's specific operations, have you acquired all of the proper manuals?

Best regards,

-a-

[Joe Larussa]

15 hours ago, carusoam said:

I wrote this a day ago thinking an answer may come about.  It didn't, so let me share what I was thinking. See if it helps.

1) If the GPSS is hooked up in the most basic way, it may only be active with the AP in heading mode.

2) The APCH mode for my AP (on the KAP150) changes the tuning function for tighter control on the approach.  The cost is a less comfortable ride if it were used during cruise.

3) do you use the heading mode to navigate through the flight then switch to approach mode prior to  beginning the procedure?

 

Question: Do you have an approach mode that is selecting a finer set of tuning Parameters?

follow-up: Have you built a chart of what is connected with all the various switch combinations?

The GPSS device is calculating many waypoints and delivering them to the GPS.  The AP is controlling the plane to follow the waypoints.  The AP has different modes that effect how the plane follows the way-points.

the person who has installed the GPSS and connected it to the AP probably has this chart.

Trying to figure this out by test flying it endlessly seams a bit rare.

The differences in analog vs digital nav, GPS vs VOR, give uncomfortable feelings until they get better understood in one's plane.

Doing this as part of an approach leaves me uneasy thinking something may not be working correctly.  Hard to fly an approach in IMC without knowing everything is working.

Is there a way to get trained on your hardware's specific operations?

If self training on your hardware's specific operations, have you acquired all of the proper manuals?

Best regards,

-a-

Agreed that GPSS is only on while in heading mode.

Nav mode seems less sensitive compared to GPSS enroute mode. Does not respond very

quickly to needle movements. I use GPSS and heading mode until after I turn onto the final

approach course. In GPSS mode flies tighter than ever. Excellent tracking and published missed

holds. Dead on! Nav mode is lazy. Going to fly a few approaches this afternoon and video tape.

Stay tuned for the next thrilling adventure

 

[carusoam]

Look how to enable the APR mode on the STec.  

I looked up an advertisement and I see a light for approach mode....  This may be the method of getting the tighter control from the AP...  STec 60-2

 

best regards,

-a-

[Joe Larussa]

31 minutes ago, carusoam said:

Look how to enable the APR mode on the STec.  

I looked up an advertisement and I see a light for approach mode....  This may be the method of getting the tighter control from the AP...  STec 60-2

 

best regards,

-a-

There is no approach mode button I guess. You hit the Nav button and it puts you into

approach mode.

 

Thanks

[carusoam]

Something would need to let it know.

Using the Nav button will make it use a nav radio as a source.  But the tightness of the control comes from something telling it is on an approach.

When I did the search, an operator manual was available for the STec.  I didn't go and read it. It was the -2 version of the Stec60.  I believe.

It seems that the person installing and setting it up may hold the answers.  Often the procedure is in the POH.

Adding the GPSS after the original install may have a whole new set of guidelines.

And of course, this is my KAP150 experience.  I have not added GPSS yet.  When I do it will get altitude preselect to go with it to minimize the memory challenges...

Look all over the panel for something that could be used as button/indicator to let the device know.  Sometimes the GPS may be responsible for 'arming' an approach.

Best regards,

-a-

[Marauder]

Joe -- what you are describing may be the soft mode. It was designed to ignore the drifting that occurs with VOR and some ILS signals. The STEC was designed years before digital signals and is an analog device. I would be curious to see the video.

Anthony -- as Joe pointed out you have the STEC in HDG with the GPSS on. If you plan on flying a precision approach, you would also have the altitude hold on. When you go to do a coupled precision approach, all you need to hit is the NAV button. You do need to be in a certain location for it to couple.

I suspect what Joe is seeing may be normal due to the soft mode. The video will tell us all.

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[carusoam]

In the blended analog/digital world...  The O flies on perfect arcs between VORs using the Nav mode.  Using the GPS to fly between the same VORs, the O drives  a straight line.

I went to see the BK guy in KTTN to get the run down on how all this stuff really works in my specific plane...

The inaccuracy between VORs is acceptable because the flyway is 4nm wide for this reason.  A localizer is similar to the VOR but has the additional accuracy built into the ground antenna.

To Get a feeling of how accurately the system is working, consider using the CloudAhoy app.  Even here there is some accuracy issues.  A portable WAAS source is better than the iPad's GPS at tracing lines in space...  CloudAhoy is a flight memory/visualization tool using google maps and recognizes various flight procedures automatically.  It has recently announced it's IFR tracking skills.  (I have not had the chance to use the IFR procedure part)

 

Best regards,

-a-

[Joe Larussa]

3 hours ago, Marauder said:

Joe -- what you are describing may be the soft mode. It was designed to ignore the drifting that occurs with VOR and some ILS signals. The STEC was designed years before digital signals and is an analog device. I would be curious to see the video.

Anthony -- as Joe pointed out you have the STEC in HDG with the GPSS on. If you plan on flying a precision approach, you would also have the altitude hold on. When you go to do a coupled precision approach, all you need to hit is the NAV button. You do need to be in a certain location for it to couple.

I suspect what Joe is seeing may be normal due to the soft mode. The video will tell us all.

Sent from my iPad using Tapatalk

So I shot three approaches today. All to the same runway. LPV with using GPSS until on the final approach course. Then switched to Nav mode. It was in soft mode and honestly it was not to bad. Then I did the Rnav in Gpss mode and it was about as good as it gets. Lastly the ILS. It was a cap soft situation and wasn't too shabby either. For some reason today was better. A little turbulence but not gusty or much wind. I think that even when doing a GPS approach as good as that can be the autopilot simulates that as an ILS. Just a theory. If I hand fly it it is as good as it can possibly be. When flying the whole procedure there is a 75 degree intercept. I can see why that might cause an overshoot then tries to get settled.

[Marauder]

Joe -- did you ever figure out which model GPSS you have? The reason I am asking is because maybe there is something unique about how it works in conjunction with your STEC. Mine is derived from the Aspen PFD. If I am flying a LPV approach, I never disengage the GPSS throughout the approach. It stays active and becomes alive when I fly the GPS missed.

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[Joe Larussa]

48 minutes ago, Marauder said:

Joe -- did you ever figure out which model GPSS you have? The reason I am asking is because maybe there is something unique about how it works in conjunction with your STEC. Mine is derived from the Aspen PFD. If I am flying a LPV approach, I never disengage the GPSS throughout the approach. It stays active and becomes alive when I fly the GPS missed.

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I'll go through my log books and check. It's a button on the panel. Don't know too much more than that. I believe it disengages after you hit the Nav button on the autopilot. I shot a video yesterday but it's kind of blurry. Hard to get a good place for a camera.

[bgpilot1]

Here are some responses I found online when troubleshooting my STEC 60-2 a while back. 

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.

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".

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"?

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.

 

[Joe Larussa]

So back at it today. ILS then LPV. Reasonable amount of crosswind and some bumps. Tried to get some video but camera placement is just not working out. Both approaches were not to shabby. I agree with Marauder that soft mode dumbs down the sensitivity for signals like Vor's. I think this sucks for ILS, localizer and any approach you really care about. I've seen other units with an actual selectable approach mode that increases sensitivity. Pretty sure this is as good as it gets with this model 60-2 which was installed 13 years ago.

[carusoam]

Joe,

Did you see BGpilot's explanation before or after your flight? You and him were typing about the same time...

he gives a great explanation of how the GPS accuracy is delivered to the AP and the required timing to make it happen properly.  Following up with how a simple mis-wiring can cause common issues.

were you able to get the STEC's APCH light to come on?

Best regards,

-a-

[Joe Larussa]

49 minutes ago, carusoam said:

Joe,

Did you see BGpilot's explanation before or after your flight? You and him were typing about the same time...

he gives a great explanation of how the GPS accuracy is delivered to the AP and the required timing to make it happen properly.  Following up with how a simple mis-wiring can cause common issues.

were you able to get the STEC's APCH light to come on?

Best regards,

-a-

I did. That was a lot of info! I can get the approach mode to come on. You just need to hit Nav when on an Rnav or ILS. I just think there is some confusion on what soft mode really means. I think soft mode reduces turn rate and approach mode increases sensitivity. Not 100 percent sure.

[carusoam]

Pressing the two buttons at the same time is hard to figure out on your own.  

The JPI has that opportunity as well.  Press two buttons to download data...

Lots Of reading to do...  Especially if you are going to use this stuff in IMC..

How's your memory working for all this stuff?  It is a lot to do.  Personal Checklists for approach are probably helpful.

Best regards,

-a-

 

[Joe Larussa]

On April 22, 2016 at 10:01 PM, carusoam said:

Pressing the two buttons at the same time is hard to figure out on your own.  

The JPI has that opportunity as well.  Press two buttons to download data...

Lots Of reading to do...  Especially if you are going to use this stuff in IMC..

How's your memory working for all this stuff?  It is a lot to do.  Personal Checklists for approach are probably helpful.

Best regards,

-a-

 

Yeah lots of button pushing for sure. I've been flying a few approaches everyday trying to learn and understand what's happening. I plan on flying ifr and don't want to second guess anything. I'm getting there but want to be sure equipment works as advertised.