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  #11  
Old 06-23-2014, 07:07 AM
petersb petersb is offline
 
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Quote:
Originally Posted by skylor View Post
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
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  #12  
Old 06-23-2014, 07:15 AM
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Peter,

Did you check if any of your x, y, z, wires to the magnetometer are crossed?
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  #13  
Old 06-23-2014, 07:40 AM
Paul K Paul K is offline
 
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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?
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  #14  
Old 06-23-2014, 07:41 AM
petersb petersb is offline
 
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Quote:
Originally Posted by TomVal View Post
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.
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  #15  
Old 06-23-2014, 07:57 AM
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tadsargent tadsargent is offline
 
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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.
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  #16  
Old 06-23-2014, 07:59 AM
petersb petersb is offline
 
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Quote:
Originally Posted by Paul K View Post
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
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  #17  
Old 06-23-2014, 08:12 AM
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johngoodman johngoodman is offline
 
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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
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  #18  
Old 06-23-2014, 08:49 AM
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KatieB KatieB is offline
 
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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.
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  #19  
Old 06-27-2014, 10:40 PM
Experimentalflyer1 Experimentalflyer1 is offline
 
Join Date: Jun 2014
Location: Bellefontaine, Ohio
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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.
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  #20  
Old 06-27-2014, 11:29 PM
tim2542 tim2542 is offline
 
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Location: Redding,Ca
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Default 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
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