Hi Tony,
I had 2 similar problems but it was with Chelton, and is probably unrelated but it may help. The 1st was I would loose the PFD after about 15 min. and we thought it was the ADHARS. It turned out we had sent the cheltons back for some work and they upgraded the software. Our Chelton displays were named #0 and #1 in the airplane when they were installed. The software upgrade would only work if they were named #1 and #2, once we named them correctly in the airplane they worked fine. This happened during the buy out of Chelton and personnel changes, it was unreal the amount of pain and suffering (and expense) we went through on that one.
The 2nd problem was we would have the oil temp increase beyond max limits and I did not think we had an oil temp. problem. Turns out I added a 2nd ground wire from the grounding buss to the other battery and this fixed the engine over temp problem. The ground path was going through the oil temp sending unit (Walter Engine) and was not large enough to carry the ground ele. loads.
What I am getting at is you are looking in the right direction with loose grounds but you may not have a large enough ground conductor for your ele. system with the addition of a 2nd alternator. You may want to revisit the ele. ground schematic to see if you need to improve your grounding system. I don't know if this is your problem but I have seen problems with composite aircraft with ground issues. I know this glass cockpit stuff is very sensitive to voltage spikes and ground issues.
Good luck, I hope this helps,
Swaid Rahn
LNC4P(Walter)
LNC4P(Garrett) in work
On Sat, Apr 30, 2011 at 6:47 PM, Tony Moradian
<tmoradia@yahoo.com> wrote:
Hello All,
I have the GRT Horizon HX dual Ahars in my Legacy. For the first 30 hours i had absolutely no problems with these units. After that first 30 hours i took it in for paint and interior and added the second alternator as well as the canopy seal system. Since then i continually lose ahars #1 within the first five minutes of engine start, and lose ahars#2 within the first hour. We have done a lot of trouble shooting to look for loose ground and/or power. The other interesting thing to note is that if turn on the system on the ground without the engine running, I never lose the ahars. I do have a Vertical Power Vp-200. I see no voltage or current alarms in the VP-200.
GRT folks seem to think that there might be an interference with the ahars if COAX is close by. Has anybody experienced anything like this?
Tony Moradian
Legacy L2K330
N444HL
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Swaid L. Rahn
Indigo Aviation, Inc.
940 Mock Road
Springfield, Ga. 31329
Cell 912.655.0966