What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

Do you need ADAHRS to make G5 work as HSI?

Sam I Am

Member
All, I'm not getting an answer from the G3Xpert on this and hoping someone knows. I have found places where it states you need Garmin's GSU 25 to use the G5 as an HSI when connected to the GPS 175 navigator and other places where it says it is not necessary. Do I need one with a new panel install like this:
 

Attachments

  • Garmin Panel - Google Docs.pdf
    426.9 KB · Views: 138
Good Morning,

The G5 is a wholly self-contained instrument in regards to ADHRS. You do not need a GSU to operate the unit as an HSI or AI.

However you do need a magnetometer, the GMU 11, and an ARINC 429 interface, the GAD 29, to operate the G5 as an HSI with a GPS IFR navigator.

From our webpage:

To provide even more situational awareness, the G5 instrument can also function as a DG or HSI in your panel. When paired with an affordable GMU 11 magnetometer and select VHF Nav/Comms or GPS navigators (interfaced with optional GAD 29 navigation data adapter), G5 can serve as your primary reference source for magnetic heading, VOR/LOC guidance and/or GPS course guidance — as well as providing distance and groundspeed indications. The unit displays both vertical and lateral GPS/VOR/LOC course deviation when available (additional equipment may be required). And you can use the G5 instrument’s rotary knob to easily make and adjust course selections — or to control heading bug settings in DG installations. Because the GMU 11 is connected to the CAN bus network, a single magnetometer can supply heading information to 2 G5 units simultaneously.

BR,

Brad
 
Last edited:
Thanks Brad...there's a post where they said they bought the ADAHRS and returned it because it wasn't needed. You cleared up my confusion. TY
 
Since you mentioned wanting to use a GPS 175 IFR navigator, here is a better picture showing the required components. As Brad said, no GSU 25 is needed.

ACtC-3fFNB92BwUatUU0eV71nq-uwhhXf-FrtagkMhGWv837F4ZnXHm_vbi6ORib8k3G7kxJQQ37nyvKtNzJwn51juZR3-mIgAJ2O2TrpRQMS4YVrXMiOH4UAk0V8DpydLuhD5na7ysyhn7GNs1nYl4xf4xZ=w640


Steve
 
I'm in the process of designing a panel with 3 G3xs and a G5. If the G3s and the G5 all rely on the same magnetometer, does that result in a single point of failure?

I thought that the entire point of having a G5 was in case everything else goes bad in IFR, I can still keep the wings level. If the G5 relies on the same data feed, what happens if that goes bad?
 
I'm in the process of designing a panel with 3 G3xs and a G5. If the G3s and the G5 all rely on the same magnetometer, does that result in a single point of failure?

I thought that the entire point of having a G5 was in case everything else goes bad in IFR, I can still keep the wings level. If the G5 relies on the same data feed, what happens if that goes bad?

Yes, if the magnetometer fails, you will have a failure. It won't be a complete failure, as the G3x's and G5 can still give you guesstimate heading information from the GPS and ADHRS data, but it will not be precise.
 
I'm in the process of designing a panel with 3 G3xs and a G5. If the G3s and the G5 all rely on the same magnetometer, does that result in a single point of failure?

I thought that the entire point of having a G5 was in case everything else goes bad in IFR, I can still keep the wings level. If the G5 relies on the same data feed, what happens if that goes bad?

If a single GMU11 is installed in the system and it fails, you will lose magnetic heading information in the entire system (GMU11 places this data on the CAN BUS). In this case, the system will revert to using GPS TRACK in its place. Dual GMU11s can be installed if this is a concern. The G5 has its own internal, independent ADHRS apart from the GSU25(s) ADHRS units driving the G3X Touch displays. The only data they receive from one single point would be magnetometer and temperature data (GMU11 and GTP59).

While magnetic and GPS information aid in stabilizing ADHRS units, it will not create loss of attitude information if these happen to be lost.
 
Last edited:
If a single GMU11 is installed in the system and it fails, you will lose magnetic heading information in the entire system (GMU11 places this data on the CAN BUS). In this case, the system will revert to using GPS heading in its place.

Not to pick nits but rather to ensure clarity and accuracy of the information provided...

In the situation where GMU11 magnetometer data is not available, I believe the more correct statement should be that G5's revert to presenting GPS GROUND TRACK.

Please correct me if this is an incorrect assumption.

To the best of my knowledge GPS has no mechanism by which it may detect or derive magnetic heading information, thus GPS is only able to use its historical breadcrumb trail plus current velocity vector information to produce a readout of ground track. Again, if this isn't correct I'd like to learn more.

If my assumption is correct, that no such thing as GPS Heading exists, it would be a good idea to edit the post above to reflect GPS Ground Track rather than GPS Heading.
 
My G5 is installed as a standalone, and backup only...no magnetometer. I get magnetic heading from the magnetometer for my EFIS. The G5 is connected to my 430W, so I do get track and course, as well as pitch and bank.
 
Why do we even care about a point that used to be in northern Canada and is now drifting rapidly (by historical standards) toward Siberia? Given the precision of GPS navigation, VOR locations, etc etc etc, it sure seems like magnetic "north" is an antiquated concept when true north is so easy to discern.

Making navigation with a modern flat panel high-precision EFIS rely on an inconsistent location sure seems like an oxymoron to me.
 
Yes - a more appropriate term would be reversion to the use of GPS TRACK. That has been edited.
 
Back
Top