[Desertsky]

I am installing a skyview system in my 9. Built an avionics rack just aft of the baggage compartment between bulkhead 706 and 707 parallel to the 718 longeron. The ADAHARS will end up about 20 inches from the pitch servo. I am worried that on servo power UP I might get some magnetic interference. Was hoping one of you all might have some experience with the servo power ON radiation levels and minimum space distance. Right now I only show about 6 inches of magnetic radiation with my compass with power off. Thanks for any help.

 

[airguy]

I put my ADAHRS all the way in the back, just forward of the empennage fairing. I'm building a mounting plate in the same location behind the baggage bulkhead just like you, and mounting the ELT, strobe power pack and Transponder in that location. I wanted to keep the ADAHRS as far away from any interference as possible, so it went in the back.

I'm going to create dual additional longerons (one shown here, the other being fabbed tonight) and put a small plate across the aft section, to make a mounting plate about 12" x 10", behind the elevator servo. It's hard to tell from the picture but the top angle is the same height as the center longeron, to give a nice flat mount for the .040" plate.

 

[DRBuilder]

I am installing a skyview system in my 9. Built an avionics rack just aft of the baggage compartment between bulkhead 706 and 707 parallel to the 718 longeron. The ADAHARS will end up about 20 inches from the pitch servo. I am worried that on servo power UP I might get some magnetic interference. Was hoping one of you all might have some experience with the servo power ON radiation levels and minimum space distance. Right now I only show about 6 inches of magnetic radiation with my compass with power off. Thanks for any help.

Mine is installed in the same place. I haven't noticed any interference when the autopilot is turned on but what I HAVE noticed is something completely unexpected... the SEATBELT CABLES are causing a 1-3 degree change in the heading! I'm not sure how the seatbelt cables became magnatized but when I move them away from the ADAHRS, the heading changes. There is obviously some magnetic interference there. I am trying to see if I can demagnatize the cables. Otherwise, I am going to need to find another location aft of the seatbelt mounting point on the longerons. In front of the HS where AIRGUY mounted his looks like it might work well except for the fact that it will be nearly impossible to access now that I am already flying.....

 

[airguy]

Mine is installed in the same place. I haven't noticed any interference when the autopilot is turned on but what I HAVE noticed is something completely unexpected... the SEATBELT CABLES are causing a 1-3 degree change in the heading! I'm not sure how the seatbelt cables became magnatized but when I move them away from the ADAHRS, the heading changes. There is obviously some magnetic interference there. I am trying to see if I can demagnatize the cables. Otherwise, I am going to need to find another location aft of the seatbelt mounting point on the longerons. In front of the HS where AIRGUY mounted his looks like it might work well except for the fact that it will be nearly impossible to access now that I am already flying.....

If you pull the fairing off, you might be able to reach in through the two holes in the aftmost bulkhead and get more work done there than you think. I did that before installing the ADAHRS there to make sure I would be able to fish it out later and work on it if needed. Worst case scenario - you lay some boards across the bulkheads in the tail and go for a crawl. Be sure an prop up the tail on some sawhorses or it will tip backward as you move aft.