G5/GNS430W/STEC 30 issues.

[oilwell1415]

This is my first post here, but since my online search for resolution to my problem has sent me here to read numerous threads on similar issues I figured I would give it a try.

I bought my plane 10 years ago with a 430W, STEC-30 and KI525 HSI in the panel. This combination worked perfectly together with no issues. About 2 or 3 months ago my attitude indicator died, so I took the plane in to an avionics shop I've used previously with excellent service to have the AI and HSI replaced with dual G5s. The service from the shop was not good this time (previous owner retired since I was there last) and I am hesitant to take the plane back to them if I can possibly avoid it.

The issue I'm having is that the STEC will no longer track or intercept a VOR or localizer course and when following the heading bug it does standard rate S turns back and forth across the course. How far it goes on either side of the course does seem to vary from 5 degrees to 20 degrees with no real pattern to it. Following a GPS course works correctly just as it did before and the altitude hold works correctly. Everything displays correctly on the G5, the autopilot just doesn't track correctly. I have tried ST, HG, High Track, and Low Track modes on the STEC and none of them work correctly with the heading bug or VOR. Switching the CDI on the 430 causes the appropriate changes to happen on the HSI as does switching between GPSS and heading mode. Since my previous HSI was a KI525 the STEC configuration is correct.

Since I noticed the heading issue first, I tried to address it by adjusting the scaling factor in the G5. This did not cause any change in how it behaved. I've also verified the config is set to SDI1 on both the G5 and the 430. I also tried setting both to common as suggested in another thread here and that didn't fix anything. I've tried going through the installation manual and verifying all of the setting are where it says they should be and it appears that they are correct.

Anybody have any ideas?

 

[midlifeflyer]

Have you gone back to the installer? Those really sound like installation issues.

 

[Clip4]

Your shop failed to install the required components to get a digital HSI to work with an analogue AP.

 

[MooneyDriver78]

I had this problem, there’s a resister or jumper inside the STEC that needs to be removed or changed to indicate the type of HSI it’s connected to, I had the NSD 360 but the G5 emulates some other kind that I can’t remember.

 

[oilwell1415]

Have you gone back to the installer? Those really sound like installation issues.

No. As I said in my original post this was not a pleasant experience and I have no desire to go back to them if at all possible. If I have to get more work done on it I will likely take it somewhere else even though it will cost me more money to do so. At this point I have no faith in the shop making it right.

Your shop failed to install the required components to get a digital HSI to work with an analogue AP.

If that was the case wouldn't it also have problems with GPSS?

I had this problem, there’s a resister or jumper inside the STEC that needs to be removed or changed to indicate the type of HSI it’s connected to, I had the NSD 360 but the G5 emulates some other kind that I can’t remember.

The STEC has to be configured for a KI525, which is what I had previously and how it is configured.

 

[midlifeflyer]

If that was the case wouldn't it also have problems with GPSS?

Not necessarily. GPSS is following heading instructions from the GPS.Not from ground-based nav.

 

[oilwell1415]

Not necessarily. GPSS is following heading instructions from the GPS.Not from ground-based nav.

If all the nav signals go to the HSI and the HSI is used to determine which one gets sent to the AP it seems like that should be an all or nothing deal if there was a piece missing. And the heading bug isn’t ground based. What am i missing?

 

[Ryan Klems]

For the VOR/LOC issue ... my guess is they ended up eliminating the +L/+R signals from the 430W to the S-tec computer. Those would normally run to the KI525 and then on to the S-tec, and they probably just completely left them unconnected. The G5 only generates course error signals (and the S-tec 30 doesn't even accept them anyway), so the autopilot needs the primary signals from the navigator for nav tracking. The lack of heading tracking but GPSS working flawlessly is very odd. GPSS through the G5 fully done through heading emulation, so if GPSS works, heading tracking definitely should as well. Could you describe what you do to engage heading tracking vs GPSS?

 

[Clip4]

Garmin is pleased to announce that the G5 electronic flight instrument will soon be compatible with a wide-range of third-party autopilots available on the market. Utilizing the new GAD 29B adapter, the G5 directional gyro (DG)/horizontal situation indicator (HSI) can interface with a variety of autopilots to provide heading and course error from G5 to drive the autopilot. With a compatible navigation source, G5 can also interface with select autopilots for coupled flight in heading and navigation modes. Additionally, when interfaced with a GTN 650/750 or GNS 430W/530W, the G5 can provide GPSS roll steering navigation from the navigator to the autopilot. Pilots can simply select GPSS on the G5 and heading mode on the autopilot and the autopilot will fly smooth intercepts, holding patterns, procedure turns and more.

Third-party autopilot support is expected to include the following autopilots:​

• Century II/III
• Century IV (AC), IV (DC)
• Century 21/31/41
• Century 2000
• Cessna 400B
• Cessna 300 IFCS/400 IFCS
• Honeywell (Bendix King) KAP 100/150/200
• Honeywell (Bendix King) KFC 150/200
• Honeywell (Bendix King) KAP 140
• Honeywell (Bendix King) KFC 225
• S-TEC 20/30/40/50/55/60-1/60-2/65
• S-TEC 60 PSS
• S-TEC 55X

 

[oilwell1415]

For the VOR/LOC issue ... my guess is they ended up eliminating the +L/+R signals from the 430W to the S-tec computer. Those would normally run to the KI525 and then on to the S-tec, and they probably just completely left them unconnected. The G5 only generates course error signals (and the S-tec 30 doesn't even accept them anyway), so the autopilot needs the primary signals from the navigator for nav tracking. The lack of heading tracking but GPSS working flawlessly is very odd. GPSS through the G5 fully done through heading emulation, so if GPSS works, heading tracking definitely should as well. Could you describe what you do to engage heading tracking vs GPSS?

According to pages 147 and 181 of the installation manual (which I reserve the right to be reading incorrectly) the only STEC models that receive a direct signal from the 430 are the 55, 60 and 65. The 30 only gets a heading correction signal from the GAD29 and the source of that correction is determined by turning the GPSS on or off in the G5 and the CDI selector on the 430.

It does track the heading bug, it just weaves back and forth across the heading. That suggests to me that the STEC is getting the signal, but the signal is telling it to do strange things.

Engaging the heading tracking is done through the G5. I push the button to bring up the menu, then scroll across to select/deselect GPSS. The heading bug does change from solid to hollow as it should. I've tried this in all modes on the STEC and none of them do this correctly. Before I had the G5s installed I switched from GPSS to heading with a switch on the panel and the STEC did everything in heading mode.

Garmin is pleased to announce that the G5 electronic flight instrument will soon be compatible with a wide-range of third-party autopilots available on the market. Utilizing the new GAD 29B adapter, the G5 directional gyro (DG)/horizontal situation indicator (HSI) can interface with a variety of autopilots to provide heading and course error from G5 to drive the autopilot. With a compatible navigation source, G5 can also interface with select autopilots for coupled flight in heading and navigation modes. Additionally, when interfaced with a GTN 650/750 or GNS 430W/530W, the G5 can provide GPSS roll steering navigation from the navigator to the autopilot. Pilots can simply select GPSS on the G5 and heading mode on the autopilot and the autopilot will fly smooth intercepts, holding patterns, procedure turns and more.

Third-party autopilot support is expected to include the following autopilots:​

• Century II/III
• Century IV (AC), IV (DC)
• Century 21/31/41
• Century 2000
• Cessna 400B
• Cessna 300 IFCS/400 IFCS
• Honeywell (Bendix King) KAP 100/150/200
• Honeywell (Bendix King) KFC 150/200
• Honeywell (Bendix King) KAP 140
• Honeywell (Bendix King) KFC 225
• S-TEC 20/30/40/50/55/60-1/60-2/65
• S-TEC 60 PSS
• S-TEC 55X

I have that.

 

[jelecroy]

When we installed GI-275's last year the installer had to change resistors in our STEC 60-2 to configure it from the old NSD-360 to work with the analog autopilot interface on the GI-275. IIRC they got to do it twice, because the first time they installed the wrong value resistors (maybe 400 Ohm when what was needed was 4k??). But I am sure that your G5 will drive an STEC if connected to match the STC.

 

[oilwell1415]

When we installed GI-275's last year the installer had to change resistors in our STEC 60-2 to configure it from the old NSD-360 to work with the analog autopilot interface on the GI-275. IIRC they got to do it twice, because the first time they installed the wrong value resistors (maybe 400 Ohm when what was needed was 4k??). But I am sure that your G5 will drive an STEC if connected to match the STC.

That was mentioned in the original post and again after that. I previously had a KI525 HSI that worked perfectly with the STEC. The G5/GAD29 have the same output as the KI525, so the STEC is configured correctly for the application.

 

[Ryan Klems]

According to pages 147 and 181 of the installation manual (which I reserve the right to be reading incorrectly) the only STEC models that receive a direct signal from the 430 are the 55, 60 and 65. The 30 only gets a heading correction signal from the GAD29 and the source of that correction is determined by turning the GPSS on or off in the G5 and the CDI selector on the 430.

Which installation manual, the G5? I don't see any references on those pages (of the current Rev 30 manual) At any rate the G5 manual is not the complete view of the interface to the autopilot, it's only showing the GAD29B interface to the navigator & autopilot. I assure you that nav tracking will not work without the +L/+R signals from the 430 being connected to the S-tec. You can see that in the GNS & s-tec manuals. The S-tec 30 only takes heading error, which won't do _anything_ to track nav, it _must_ be connected to the navigator +L/+R signals.

It does track the heading bug, it just weaves back and forth across the heading. That suggests to me that the STEC is getting the signal, but the signal is telling it to do strange things.

The GPSS will emulate the same heading commands, which is why it is very odd that actually heading tracking is working odd.

Engaging the heading tracking is done through the G5. I push the button to bring up the menu, then scroll across to select/deselect GPSS. The heading bug does change from solid to hollow as it should. I've tried this in all modes on the STEC and none of them do this correctly. Before I had the G5s installed I switched from GPSS to heading with a switch on the panel and the STEC did everything in heading mode.



I have that.

The S-tec 30 will only work properly to track heading (and GPSS) with the S-tec in Heading (HD) mode. I know you had a KI-525 before, did you also have GPSS through an ST-901 (you mention having a switch in the panel) ... if so, then your S-tec 30 was _not_ configured for KI525, it would have been strapped for the ST-901, so would need to be re-strapped to a KI525/KCS55 heading.

 

[oilwell1415]

Which installation manual, the G5? I don't see any references on those pages (of the current Rev 30 manual) At any rate the G5 manual is not the complete view of the interface to the autopilot, it's only showing the GAD29B interface to the navigator & autopilot. I assure you that nav tracking will not work without the +L/+R signals from the 430 being connected to the S-tec. You can see that in the GNS & s-tec manuals. The S-tec 30 only takes heading error, which won't do _anything_ to track nav, it _must_ be connected to the navigator +L/+R signals.


The GPSS will emulate the same heading commands, which is why it is very odd that actually heading tracking is working odd.


The S-tec 30 will only work properly to track heading (and GPSS) with the S-tec in Heading (HD) mode. I know you had a KI-525 before, did you also have GPSS through an ST-901 (you mention having a switch in the panel) ... if so, then your S-tec 30 was _not_ configured for KI525, it would have been strapped for the ST-901, so would need to be re-strapped to a KI525/KCS55 heading.

Yes, the G5 manual. I don't know which rev I was looking at since I don't have it in front of me. In the Rev 30 the diagrams I was referring to are on pages 132 and 186, but I think that will end up being irrelevant.

I did have an ST-901, but was under the impression it was just a pass through for the data and didn't actually change anything. This sounds like it may be the key and I will investigate it this weekend.

 

[Ryan Klems]

Yes, the G5 manual. I don't know which rev I was looking at since I don't have it in front of me. In the Rev 30 the diagrams I was referring to are on pages 132 and 186, but I think that will end up being irrelevant.

I did have an ST-901, but was under the impression it was just a pass through for the data and didn't actually change anything. This sounds like it may be the key and I will investigate it this weekend.

Yeah, the ST-901 would have been strapped for the KI525 and the S-tec 30 would have been strapped for the ST-901. That's quite possibly the issue with the heading tracking (though I still don't understand how GPSS is working properly), but the lack of nav tracking will be entirely due to the missing analog +L/+R signals between the 430 and the S-tec 30. The drawing on pg 186 just shows that there would need to be a ARINC 429 (digital) connection to the 55X, as that model has built in GPSS. However, even the 55X would still require the analog connections to the navigator in order to do nav tracking. The analog connection requirement for the 3rd party autopilots is actually the entire reason why you are forbidden by the STC from having two navigation sources connected to the G5s when the G5s are interfaced to a 3rd party autopilot. Since there is no internal switching of those analog signals, it would be possible to be displaying one thing on the G5 and the autopilot flying another. The GI-275s, on the other hand, have internal switching and provide the analog outputs to the autopilot properly and does not have the same limitation. Perhaps this drawing for the GI-275 will help... if one could get by without the analog signals, wouldn't the GI-275, a more advanced piece of hardware than the G5 system, not need them?