Message-ID: <000e01c03997$959e5340$64888ec6@user>
From: "Robert Overmars" <rovermars@optusnet.com.au>
To: "lancair list" <lancair.list@olsusa.com>
Subject: Strike finder antenna placement
Date: Thu, 19 Oct 2000 16:40:15 +1000
Reply-To: lancair.list@olsusa.com
Mime-Version: 1.0

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G'day all,

On VH-LWB we had an interesting experience with the placement of the strike
finder antenna, we mounted it as advised by Strikefinder on the underside of
the fuselage as far aft as practible in a 'quiet' electrical area. It ended
up being mounted between the gear doors about half way between the hydraulic
manifold block and the forward face of the gear wheel well, on the underside
of the fuselage.

We discovered that the workshop flourescent lights showed up on the
strikefinder display, particularly the smaller hand held ones - you could
move the lights around and the strikefinder display would track the light
but even after turning off all things electrical in the workshop the display
would at times still show a raging electrical storm right on the nose of the
aircraft. This led to much head scratching and eventually the culprit was
found.

The problem turned out to be the hydraulic pressure switch mounted as per
instructions on the manifold block just forward of the antenna. On this
aircraft we have modified speed brakes operated hydraulically and controlled
by an electrical solenoid valve. This valve is a spool type and has a very
small internal leakage which over time ever so slowly bleeds away hydraulic
pressure causing the hydraulic pressure switch contacts to slowly but surely
come together generating a miniature electrical storm inside the switch as
electricity arced across the almost touching contacts - a miniature storm
just a few inches from the antenna!

The solution was to replace the Lancair pressure switch with a quality
component with snap action contacts and the problem was solved. If any of
you out there have mysterious electrical storms on the nose when it's 8/8ths
blue it just might be your pressure switch playing up!

Robert Overmars.     Taree,  Australia.


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Please send your photos and drawings to marvkaye@olsusa.com.
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