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Date: Wed, 29 Dec 2010 21:21:36 -0500
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From: mmcmanus@grandecom.net
Subject: Re: [LML] P-STATc?
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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 =20
intermittent.  Flying along and randomly the unit would display GPS =20
signal lost, wait 3 or 4 minutes and the GPS would come back up.  It =20
might happen again within a few minutes or it might not happen the =20
rest of the trip.

I checked the basic lose connection type stuff, and then broke down =20
and took it to an avionics shop after it happened while I was under =20
the hood on an IFR recurrency check ride.

Turned out I have an early 430 unit that is 28v.  There is a converter =20
box that converts my 14v system to 28v for the 430.  That was failing =20
intermittently and causing the problem.  They replaced this little =20
$600 converter box and all is right again.

Matt McManus
LNC2 360


Quoting Ross Leighton <rossl@mweb.co.za>:

> Hi Guys
>
> I=B9ve got an irritating persistent problem with my Legacy electrical syst=
em.
> The pilot=B9s 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 equipmen=
t.
> Then voltage spikes were suspected but after putting an oscilloscope on th=
e
> 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 the=
y
> 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 a=
nd
> 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=B9d rather not do if there will be no improvement. If anyone has a=
ny
> similar experiences, I=B9d 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 wit=
h
> my solution search for this problem.
>
> BTW if anyone wants a copy of that Lancair P-STAT document PM me and I=B9l=
l
> send it. Interesting reading.
>
> Thanks
>
> Ross Leighton
> Cape Town, South Africa
>