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06-23-2014, 07:07 AM
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Join Date: Mar 2008
Location: Toronto
Posts: 328
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Quote:
Originally Posted by skylor
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
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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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RV7A New Dec 2013 - 360, C/S, slider
RV6 - 1600 Hours ---- Sold
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06-23-2014, 07:15 AM
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Join Date: Dec 2007
Location: SC & CA
Posts: 907
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Peter,
Did you check if any of your x, y, z, wires to the magnetometer are crossed?
__________________
Tom Valenzia
RV8 (Sold)
RV12 Jabiru 2200 Powered (Sold)
Dues contributor since 2007
Learn from the mistakes of others. You won't live long enough to make all of them yourself...Anonymous
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06-23-2014, 07:40 AM
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Join Date: Mar 2009
Location: Grand Rapids, MI
Posts: 1,004
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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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Paul K
West Michigan
Unfortunately in science, what you believe is irrelevant.
2020 donation made, exempt but worth every dime!
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06-23-2014, 07:41 AM
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Join Date: Mar 2008
Location: Toronto
Posts: 328
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Quote:
Originally Posted by TomVal
Peter,
Did you check if any of your x, y, z, wires to the magnetometer are crossed?
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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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RV7A New Dec 2013 - 360, C/S, slider
RV6 - 1600 Hours ---- Sold
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06-23-2014, 07:57 AM
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Join Date: Jan 2006
Posts: 307
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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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Tad Stripes Sargent
GRT HXr Glass
TITAN POWERED IO-370
Hartzell's advanced composite propeller
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06-23-2014, 07:59 AM
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Join Date: Mar 2008
Location: Toronto
Posts: 328
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Quote:
Originally Posted by Paul K
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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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
__________________
RV7A New Dec 2013 - 360, C/S, slider
RV6 - 1600 Hours ---- Sold
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06-23-2014, 08:12 AM
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Join Date: Feb 2006
Location: Peachtree City, Georgia
Posts: 440
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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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John Goodman - 40572
First flight was 25 June, 2011
N711JG
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06-23-2014, 08:49 AM
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Join Date: Jun 2010
Location: Stilwell, KS
Posts: 1,096
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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.
__________________
Katie Bosman
RV-3B sold, but flying!
Next project: ???
Builders gonna build...
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06-27-2014, 10:40 PM
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Join Date: Jun 2014
Location: Bellefontaine, Ohio
Posts: 3
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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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06-27-2014, 11:29 PM
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Join Date: Aug 2009
Location: Redding,Ca
Posts: 633
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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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