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I had a similar symptom that took me to a much different solution.
I had a problem with my GNS430W losing the GPS signal. It was intermittent. Flying along and randomly the unit would display GPS signal lost, wait 3 or 4 minutes and the GPS would come back up. It might happen again within a few minutes or it might not happen the rest of the trip.
I checked the basic lose connection type stuff, and then broke down and took it to an avionics shop after it happened while I was under the hood on an IFR recurrency check ride.
Turned out I have an early 430 unit that is 28v. There is a converter box that converts my 14v system to 28v for the 430. That was failing intermittently and causing the problem. They replaced this little $600 converter box and all is right again.
Matt McManus
LNC2 360
Quoting Ross Leighton <rossl@mweb.co.za>:
Hi Guys
Iıve got an irritating persistent problem with my Legacy electrical system.
The pilotıs EFIS (MGL Voyager) keeps losing its GPS fix until finally it
bombs out. Initially we suspected the instrument but MGL to their credit
have replaced it twice and still it occurs, so probably not their equipment.
Then voltage spikes were suspected but after putting an oscilloscope on the
MGL wiring all was found to be fine. So I began casting around for other
suspects. It was suggested by MGL that static discharge into the carbon
airframe could be the cause. After reading the Lancair P-STAT document they
supply with their static wicks kit, I came across this passage:
I decided to check the continuity of the airframe and discovered that the
outer wing panel carbon skin was not electrically connected to the inner
wing carbon skin. Similarly the elevator and rudder carbon skins were not
continuous with the rest of the airframe. So as a first step, I used some
copper braid to bond the inner and outer wings carbon skins electrically and
now have continuity. But after a test flight today, same old problem. So
that leaves the elevator and rudder to do.
However, this will be no easy task and will require removing the surfaces,
which Iıd rather not do if there will be no improvement. If anyone has any
similar experiences, Iıd like to hear:
1. whether you have done anything to ensure the whole airframe is
conductive;
2. how you electrically bonded the elevator and rudder to the rest of the
airframe (I initially thought the hinge posts took care of that but they
attach to a non-conductive glass spar); and
3. whether any of this is worthwhile. I may be completely off the mark with
my solution search for this problem.
BTW if anyone wants a copy of that Lancair P-STAT document PM me and Iıll
send it. Interesting reading.
Thanks
Ross Leighton
Cape Town, South Africa
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