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GRT HXr horizon tilted

petersb

Well Known Member
Horizon line does not show wings level after a turn, even though they are.

This seems to be occurring mostly after a climbing or descending turn, although it has happened when level.

The magnetometer has been tried in two locations and has been checked for level and calibrated.

My backup Dynon D10A does not show this behaviour, it's remote magnetometer is located in the tail, one of the tested locations for the HXr magnetometer.

Getting frustrated.

Peter
 
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Welcome to the party. You too are a beta tester. Wait until you can get the heading to indicate 270 when you are actually flying 090 for many minutes.
 
Welcome to the party. You too are a beta tester. Wait until you can get the heading to indicate 270 when you are actually flying 090 for many minutes.

I thought their software was based on their earlier products and thus mostly sorted out
 
Sorry to hear about your issue. You are not a beta tester. You have an issue with the installation or setup. I have 100% confidence in IFR conditions with my HXr and have for over a year. call Ben or Katie tomorrow, they will help sort this out.
 
Sorry to hear about your issue. You are not a beta tester. You have an issue with the installation or setup. I have 100% confidence in IFR conditions with my HXr and have for over a year. call Ben or Katie tomorrow, they will help sort this out.

Tad, thanks for the reply. I have spoken to the good people at GRT several times and have tried all of their suggestions, no luck to date. Thought I would try the forum.

Don't recall this problem in the first 50 hours
 
Ok. Question one, where is the magnetometer positioned
And two, where is the AHRS located.

AHARS is just behind the firewall, magnetometer first location was the first rib behind the baggage compartment.(F707, aircraft is rv7A) on the bottom It is installed 16 inches behind the pitch servo, I checked for magnetic interference and couldn't find any.

Second location is under the vertical stabilizer, next to the Dynon magnetometer which is working OK. Again couldn't find any magnetic anomaly , also ran the elevator up and down and did not detect any changes on the display due to elevator control horn.

I monitored the magnetometer heading ( Set menu>AHARS Maintenance )while sitting in the hanger, engine off, it quickly flickered between 288 and 294 while the Gyro heading remained at 292 steady
 
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Issue?

Welcome to the party. You too are a beta tester. Wait until you can get the heading to indicate 270 when you are actually flying 090 for many minutes.

Based on this and other comments you've made, you clearly have a beef with GRT.

I have 320 hours behind a GRT Horizon (purchased in 2006) including about 60 hours of hood time in my RV-8, and it has not missed a beat.

I would encourage the original poster to be absolutely certain to follow the installation instructions for the AHRS and Magnetometer perfectly, especially with regards to alignment to each other and the airframe. In my -8, the wingtip was the only location that I felt would be as free as possible from magnetic interference.

Skylor
RV-8
 
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I have 320 hours behind a GRT Horizon (purchased in 2006) including about 60 hours of hood time in my RV-8, and it has not missed a beat.

Skylor
RV-8

Similarly, my old Horizon is rock solid but during Phase 1 it gave odd heading readings once and tumbled once. The root cause was me not waiting for the system to fully boot before I started to taxi. Peter, are you waiting for the AHRS to boot fully?
 
Similarly, my old Horizon is rock solid but during Phase 1 it gave odd heading readings once and tumbled once. The root cause was me not waiting for the system to fully boot before I started to taxi. Peter, are you waiting for the AHRS to boot fully?

Yes, the boot up takes about two minutes and the synthetic vision display starts to work at the end of the boot up, also timer disappears.

In regards to wing tip location the instruction say to locate not too close to trailing edge plus not too close to landing light wires, can't do both.

After breaking my neck relocating from inside fuselage to tail this weekend without any real change, or magnetic interference indications, I am reluctant to go through the effort to relocate to the wing just to try . Of course I will do it if I can be sure it is worth it.
 
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Based on this other comments you've made, you clearly have an issue with GRT.

I have 320 hours behind a GRT Horizon (purchased in 2006) including about 60 hours of hood time in my RV-8, and it has not missed a beat.

I would encourage the original poster to be absolutely certain to follow the installation instructions for the AHRS and Magnetometer perfectly, especially with regards to alignment to each other and the airframe. In my -8, the wingtip was the only location that I felt would be as free as possible from magnetic interference.

Skylor
RV-8

Alignment of AHARS is 2.2 degrees Up as sitting in the hangar, using "set menu"
readings. The magnetometer is 1.6 degrees
 
When I removed my Magnetometers and reinstalled them, I switched a pair of wires (red/black, black/red or something like that) and it acted about like you are describing. Just to clarify, did it work properly before you relocated the magnetrometers?
 
Peter,

Did you check if any of your x, y, z, wires to the magnetometer are crossed?

No, but I have flown it for 80 hours, all other functions including auto pilot are working, initially it seemed to be OK

Also the horizon tilt does correct itself after a minute or so

I do notice that when I fly on different headings, same altitude and speed, the Wind speed and wind direction read outs are not consistent.
 
An easy step is to recalibrate the magnetometer. Find a new compass rose, turn everything on that you can think of, including the engine and run the calibration test, twice if necessary. The wind corrections you mention will go away.
 
When I removed my Magnetometers and reinstalled them, I switched a pair of wires (red/black, black/red or something like that) and it acted about like you are describing. Just to clarify, did it work properly before you relocated the magnetrometers?

No, I relocated the magnetometer because of the tilt problem. Of course I duplicated the wiring when I extended the cables to relocate to the tail. Maybe you have something here, will check wiring this morning
 
I'm quite familiar with this problem - I had it, as well. My HX was doing fine for two years, then it suddenly started the "crazy" horizon, as described. I worked with GRT, and followed their suggestions. I remounted the AHARS and Magnometer, and checked for distance. By the way, I have them mounted behind the baggage bulkhead on an elevated rack in my RV-10.

The only thing I could find, that might be a possibility, was the steel cables for the back seat shoulder harnesses. They were close to the minimum distance. Since my mind is a steel trap (usually closed, and sitting on a shelf doing nothing), I began to wonder if they would "wander around" if there was no force holding them straight (people in the back seats). So, how to fix it.

I decided to keep the cables as far away as possible, by securing them to a nearby lightening hole, with a cable tie - it worked. No problems since. I used the smallest cable ties I had - they should break pretty easy if necessary.

Since then, I try to let the HX fully boot before taxi, but the problem seems to be gone. Basically, it was ferrous metal at a supposed minimum distance, but not really.

John
 
Hi Peter,

The suggestions here are all good, especially recalibrating the magnetometer now that you've moved it. Are you using the magnetic data on the EFIS to test for interference? (See Section 4.3 of the HXr installation manual, Magnetometer Location Validation.) If you're using a compass to test for magnetic interference in the vicinity of the magnetometer, it's better than nothing, but it's really not sensitive enough.

Sorry you're having trouble--we will get you sorted out!

Scott Card, as I've suggested before, please give our EFIS tech support a call and let us help you fix your system. I know it's an older Horizon I WS system, but we still support it. I hate to see anyone not happy with our equipment. There are many original Horizon I systems that have been flying for 10 years or more and still going strong.
 
Hello Peter,

I have experienced the same issue with my GRT Sport. It's really frustrating! GRT's tech support will offer to help and it will seem encouraging at first. Unfortunately, in my experience, they will clam up immediately if you balk at their request to move the magnetometer. I was hoping they would help me improve my current location by working through options like shielding or finding disturbances and eliminating them. They won't do it and they won't offer any reasoning. They just go silent!

I built my Midget Mustang with the magnetometer in mind and I don't think any place else in the plane is going to be better. It's a little plane, so I have few options.

Good luck to you. I forecast that they will ask you to keep moving the magnetometer until it starts working or you give up.
 
Magnetometer calibration

Dumb question but did you calibrate the magnetometer? If you are not getting a winds aloft report you don't have a good mag cal.
Tim
 
Dumb question but did you calibrate the magnetometer? If you are not getting a winds aloft report you don't have a good mag cal.
Tim

Yes, magnetomer was calibrated. I have also relocated it to the wing tip as recommended by GRT.

Have seen some improvement although still not perfect.

Started a new thread " am I expecting too much from my EFIS" with some results
 
Just another data point. We have the same system, the Horizon HXR, with the magnetometer in the tail and the AHRS on a shelf between the panel and the luggage compartment. Installed in February. No problems.
 
want to do it right the first time

Getting ready to install magnetometer in right wingtip against the outermost rib in my 6A. A check with the iPhone compass app shows no disturbance in The Force with nav lights or landing lights or aileron movement.

Do I align the magnetometer base parallel to the longeron (where I would rest my elbow when the canopy is open) for a level datum? Just checking that that's the desired level reference.

-Stormy
 
spoke too soon

After I drilled holes for the magnetometer bracket in the outboard right wing rib, I rechecked the magnetic interference status with my iPhone 5S digital compass and the results were NOT as before. For a mounting location, I had split the distance between the aileron counterweight pipe and the conduit aft of the spar that carries the landing light and nav light wires.

I found a 3 degree variation in reading when moving the aileron to its full limits of travel, and a 7 degree variation switching the landing light on/off. When I checked a few days ago, it was 1-2 degrees max. (Didn't bother checking the nav light this time, since the landing light interference is a show-stopper.) Then I reset the iPhone to try again with a fresh calibration. The compass reading swung from a steady 76* to 83* when the landing light was turned on -- and remained at 83 degrees when the light was turned back off. I can't understand how a flux gate compass can get "stuck" in a new position, but that was what seemed to be happening. The upshot is I no longer trust the iPhone compass functionality.

To avoid real headaches for myself later in the install, I am going to invest in a Silva compass or something analog and old-school to evaluate potential magnetometer locations. I'm already thinking that shortening the conduit back one bay from the tip and drilling a hole through the spar web for that landing light wire might not be sufficient to get rid of the interference. The light grounds directly to the frame, so there is no way to twist a ground return lead with the B+ wire and cancel the magnetic field.

I may be joining the ranks of those who mount their magnetometer in the tail cone somewhere. I wonder if under the empenage fairing is a workable place. Big bolts nearby, I suspect.

This is a disappointment, as at first look, it seemed the magnetometer in the wingtip was going to be bolt-and-fly easy. :mad:

-Stormy
 
Just a note, the iPhone compass is notoriously bad and relies heavily on a GPS signal. The iPhone 6 is better, but the 4 and 5s aren't very good.

You might consider wiring up a long harness to a magnetometer box and use the GRT display to see variance in the readings. With a long harness you could temporarily affix the magnetometer where you intend to try installing it.
 
After further research...

I think the consensus is the tail cone shelf below the VS is usually a reliable magnetometer location on the -6A and similar.

The only hassle is the wiring; no pre-installed conduit there like I had in the wing.:(
 
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