Hi Guys

I’ve got an irritating persistent problem with my Legacy electrical system. The pilot’s 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 I’d rather not do if there will be no improvement. If anyone has any similar experiences, I’d 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 I’ll send it. Interesting reading.

Thanks

Ross Leighton
Cape Town, South Africa