Garmin 175 holding question

[mooney87n]

Looking for a little help. I have been working on teaching myself some IFR and I am having trouble understanding why my Garmin 175 GPS wont fly a normal holding pattern with the autopilot (STEC30). I had the same result in the airplane as on the Garmin GPS simulator. The plane initially will fly to a fix, and begin a procedure turn, but instead of making the 180 degree turn in time inbound back to the IAF, it makes a full circle onto the unprotected side of the procedure turn. Is the GPS just not capable of flying a hold? I recorded a video on the Garmin simulator and included the track from my flights as well. Thanks for any help, sorry if this is kind of dumb.
here is a video of what I'm talking about, https://drive.google.com/file/d/1sqnSgZ6jCKLda5qUU2Abi-f7xP1K-ohM/view?usp=sharing

 

[tsts4]

So not familiar with the 175's or STEC30's operation, but assuming the hold (HILPT) or PT is part of the approach, are you loading AND activating the approach on the 175 prior to the IAF and is the STEC30 in Nav or Approach mode?

 

[Chip Sylverne]

The 175 will fly a hold as part of an approach or as charted just fine. If it is an uncharted hold, you need to define the inbound course.

It's all in the manual.

 

[RussR]

Can't access the video.

Do you have a GPS Steering module to interface with your STEC 30, and have GPSS engaged? It won't fly a holding pattern without it.

 

[mooney87n]

So the procedure turn is published, and selected in the approach. The airplane will fly to the initial fix with the correct transition selected the procedure turn will turn purple as the active leg and it will start to fly the turn but instead of making a normal holding pattern back inbound it makes a large circle way off course before making it back to the IAF. I must be doing something wrong

 

[RussR]

So the procedure turn is published, and selected in the approach. The airplane will fly to the initial fix with the correct transition selected the procedure turn will turn purple as the active leg and it will start to fly the turn but instead of making a normal holding pattern back inbound it makes a large circle way off course before making it back to the IAF. I must be doing something wrong

This sounds exactly like what it will do without a GPSS module. Do you have one?

If you don't know what I'm talking about, that is definitely one of the perils of trying to teach yourself IFR.

 

[Hang 4]

What's the rest of your avionics? Specifically, do you have a G5, GI275, Aspen etc? or as @RussR mentioned a GPSS module?
A couple thoughts come to mind;
- What mode is the STEC 30 in? Generally Heading follows GPSS signals
- In heading mode, no GPS involved, if you make a large change in heading, does it make a standard rate turn?

STEC 30's can have issues where they can't make a standard rate turn due to either servo's or the control head. They also will behave pretty strangely if the wrong mode is selected. I got rid of mine due to the standard rate turn issue and the cost/uncertainty of repair.

Having said all that, this is not a great area to self-teach IMHO. Find a CFII familiar with your avionics and invest an hour in getting some training.

 

[mooney87n]

I bet that is what it is.. I am honestly not sure if I have GPSS. I guess the garmin 175 does not come with it. Will figure out if I have it today. The rest of my avionics are steam gauges and i have a lynx L3 / fis-b transponder.
I thought it was strange that the Garmin GPS simulator had the same problem as my airplane.
I fixed the access to the video in my original post for those tying to help me and couldn't see it, sorry about that. Really appreciate the help.

I have a lesson with a CFII this weekend, figured I would try to get some of the basics figured out on my own.

 

[asicer]

I bet that is what it is.. I am honestly not sure if I have GPSS. I guess the garmin 175 does not come with it.

The 175 does. However, you need additional hardware between the GPS and a legacy autopilot like the STEC30. A Garmin G5 or GI275 HSI will do it, but you have to manually put it in GPSS mode.

 

[Hang 4]

The fact it's doing that in the simulator kind of rules out the autopilot. From the video, I can't see enough of what you are doing to know what the issue is, but it should follow the magenta line if the approach is activated. I suspect there is something in how you are setting up the approach that is causing the issue, but need to see the whole flight plan and the buttons you're pushing to make any better suggestion.

 

[RussR]

I bet that is what it is.. I am honestly not sure if I have GPSS. I guess the garmin 175 does not come with it. Will figure out if I have it today. The rest of my avionics are steam gauges and i have a lynx L3 / fis-b transponder.
I thought it was strange that the Garmin GPS simulator had the same problem as my airplane.
I fixed the access to the video in my original post for those tying to help me and couldn't see it, sorry about that. Really appreciate the help.

I have a lesson with a CFII this weekend, figured I would try to get some of the basics figured out on my own.

This is likely a pretty simple matter of not understanding what you have, and will be explainable in your airplane very quickly with a competent CFII.

GPSS is NOT a function of the GPS itself. Nor is it a function of the autopilot, for older units like the STEC 30. It's an interface between the GPS and older autopilots, either a separate button or often built into a glass PFD. It's essentially a "hack" to make older autopilots work with the GPS, by feeding continuous heading inputs to that portion of the autopilot. Otherwise you're stuck with NAV mode, which only looks at the CDI needle and tries to follow it, generally doing an okay but not great job. And in NAV mode it can't fly holding patterns.

There are several layers of understanding necessary here to make the avionics work the way you want. A CFII is the best way to accomplish that, and make sure you understand things correctly, and thoroughly, before you develop ingrained misunderstandings and habits.

 

[tsts4]

Do you have a really high IAS set on the Sim? If you do, try a normal approach setting like 120KTS and see it that fixes the issue.

 

[midlifeflyer]

AFAIK, no native GPSS with the 30. There is an add-on module available. Without it, you treat it like a VOR and steer yourself around the hold in heading mode by manually turning the heading bug and back to NAV when intercepting inbound.

 

[TCABM]

The fact it's doing that in the simulator kind of rules out the autopilot..

I ran it just fine at 173 KTS in the trainer. Parallel entry due to the setup is the only difference.

I think OP has a buttonology problem and may not have a GPSS box in his plane.

 

[tsts4]

I ran it just fine at 173 KTS in the trainer. Parallel entry due to the setup is the only difference.

I think OP has a buttonology problem and may not have a GPSS box in his plane.

I did too at 600 KTS and it replicated the issue the OP was having. When using the sim and you want to speed things up best to change the time setting to 5x, 10x, or 15x vs setting the IAS to some ridiculous IAS.

 

[midlifeflyer]

The fact it's doing that in the simulator kind of rules out the autopilot. From the video, I can't see enough of what you are doing to know what the issue is, but it should follow the magenta line if the approach is activated. I suspect there is something in how you are setting up the approach that is causing the issue, but need to see the whole flight plan and the buttons you're pushing to make any better suggestion.

The 175 is giving the appropriate instructions. No different than the larger 650 and 750. But without GPSS capability (whether internal or the add-on “hack” @RussR described; there are several), the AP doesn’t understand the turn commands for the outbound and intercept. It only understands the needle which is set to the inbound course.

 

[midlifeflyer]

I did too at 600 KTS and it replicated the issue the OP was having. When using the sim and you want to speed things up best to change the time setting to 5x, 10x, or 15x vs setting the IAS to some ridiculous IAS.

Too fast for the turns. Consider the bank angle required to fly a standard rate turn at 600 KTS. Yes, for a realistic simulation, speed up the simulator, not the airspeed.