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  #1  
Old 04-18-2019, 03:09 PM
Reflex Reflex is offline
 
Join Date: Jan 2015
Location: Kansas
Posts: 153
Default Garmin Magnetometer Placement (Again!)

I know this has been covered and there are about as many answers as there are posts on this subject, but I have to ask. Given that Garmin has very specific recommendations on where not to place the magnetometer, where did you put it and why?

Based on the table below, it appears that there's really no place on an RV that truly meets all the requirements. My guess is that the best place may be on the right outside rib as far back from the strobes as possible (should be able to do 3+ feet).

I'm working on the -14 and the ADHARS shelf appears to be in violation of several of these recommendations; specifically, the landing gear and the heated pitot are too close.

In addition, a shelf behind the bulkheads is too close to the rudder cables, the stabilizer deck is too close to the tailwheel, etc.

See the table below from page 8-3 in the installation manual.

Thoughts?


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Last edited by Reflex : 04-18-2019 at 03:26 PM.
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  #2  
Old 04-18-2019, 03:27 PM
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JTJones JTJones is offline
 
Join Date: Jun 2015
Location: Haleiwa, HI
Posts: 101
Default I put in in the tailcone



We made a bracket and mounted it in the Tailcone on the top of the F-01407 bulkhead. I've had no issues with it mounted there.
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  #3  
Old 04-18-2019, 03:28 PM
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Av8rRob Av8rRob is offline
 
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Location: Rescue, CA. KROB
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I put my pitot on the right side to avoid this situation.
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  #4  
Old 04-18-2019, 04:26 PM
snoop9erdog snoop9erdog is offline
 
Join Date: Oct 2005
Posts: 259
Default

I'm planning on Pitot in the left wing, Magnetometer right wing (don't want it in the bag because I'm going tailwheel and don't want unnecessary weight aft CG).

But even then.....My magnetometer will be relatively close to the right wing roll servo....

So you are right...numerous ways to skin the cat and they are not perfect per Garmin's letter of the law.
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  #5  
Old 04-18-2019, 05:11 PM
Nova RV Nova RV is offline
 
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Location: Leesburg, VA
Posts: 444
Default

I used the kit mounting bracket and location for a GMU 22 in the left wing. No issues and passed all testing.
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  #6  
Old 04-18-2019, 07:45 PM
Don E Don E is online now
 
Join Date: Aug 2016
Location: West Chester, PA
Posts: 107
Default Same as Chris in my RV-14.

Quote:
Originally Posted by Nova RV View Post
I used the kit mounting bracket and location for a GMU 22 in the left wing. No issues and passed all testing.
No issues at all.
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  #7  
Old 04-18-2019, 10:08 PM
JDA_BTR JDA_BTR is offline
 
Join Date: Dec 2013
Location: Baton Rouge, LA
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I put the GMU22 in the left wing on the shelf. I had a pitot heat controller that made the magnetometer crazy. When I went to a pitot heater that was just "on" and not with a controller, the magnetometer was good with it. My strobes and lights don't affect it at all, nor anything else inboard.

When I had the heat controlled pitot it didn't matter how I ran the power, or the ground, or anything; I tried quite a few cabling options. The only thing that mattered was if that controller was present. No controller no problem with simple twisted wire power to the pitot and ground at the wing root fuselage ground point.

The reason is that the dynon controller I had wasn't doing proportional control of current to keep the temp. It was On/Off and every on/off transition made a big flux change at the magnetometer. Having a simply switched heater has gotten rid of this big flux at every on/off of the controller transistor. Also, the controller was by design grounded at the base of the transistor to the case and thus to the airframe. I don't think this was the problem though because the flux effect at the magnetometer didn't go away with the controller hanging in space off the plane.

It should be possible to put a better control loop in the heat controller to get away from the simple on/off and make the control proportional (and more steady with less magnetic flux); but that is a manufacturer thing....
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  #8  
Old 04-19-2019, 06:21 AM
JHartline JHartline is offline
 
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Location: Carrollton, GA 5GA2
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Mine is in the left wing location. I used the factory harness, G3X touch panel and everything that goes with it, unregulated pitot, LED lights, everything done pretty much per the plans. I ran the interference test several times because the results were so low I thought I might be doing it wrong.
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  #9  
Old 04-19-2019, 07:08 AM
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kbalch kbalch is offline
 
Join Date: Jan 2005
Location: Clermont, FL
Posts: 524
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Quote:
Originally Posted by Nova RV View Post
I used the kit mounting bracket and location for a GMU 22 in the left wing. No issues and passed all testing.
Exactly what I'm doing, too. No need to overthink this...
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  #10  
Old 04-30-2019, 09:37 AM
pentoli pentoli is offline
 
Join Date: Oct 2016
Location: Riehen, Switzerland
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I am just about to order the Garmin instruments. Why did you chose the GMU 22 over the GMU 11?
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