Forwarded from the bounce bin. Message is from : "Paul Stewart"
<paul-d.stewart@virginnet.co.uk
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Steve
We have just fitted a set of wing tip nav/stobe units to our XS and have
got PFA approval for them. What you are suggesting sounds very similar
to our installation. We have used Whelen A600-PG-PR14 nav/stobe units
but the Airworld SkyflashSFD2 flasher unit.
Talking to John Tempest (PFA Engineering ) at an aerobatics comp earlier
in the year, his only comment was that since the XS does not have a wing
tip rib, the wing tip is structurally important rather than cosmetic,
thus what ever you do to the wing tip you must re-establish its
structural integrity.
What we ended up doing was to make a plywood template of the strobes
back plate covered this in cling film, cut a hole out of the wing tip
around the template and recess it into the wing tip. We then laid up a
flox fillet from the template edges onto the inside surface of the wing
tip and covered the whole with 3 plies of BID lapped 2 - 3 inches onto
the wing tip inner surface. After cure we cut a keyhole shaped hole in
the lay up to accept the strobe bulb and the wire connections. The
nav/stobe unit now sits with its base plate recessed into the wing tip
and is secured with 3 MK1000-04 anchor nuts (held with 2x TAPK 33BS
rivets each).
As you say the wires come out of the unit pointing directly at the spar
end. We have run the wires down a 13mm PVC conduit which exits the wing
root next to the pitot/static tubing (this also now runs in a conduit).
The conduits are anchored with flox as they pass through all the ribs
(including root ) and by a BID strip atthe spar end. Wire connections at
the wing tip are staggered but spliced and heat shrink wrapped. At the
root end there is a 3 pin heat shrink wrapped connector which hangs
loose to connect but can then be clipped to the fuselage to prevent
rattling. The cables run forward of the spar in the wing root fairing
together with the pitot / static tubing to enter the fuselage. Make sure
you have enough spare wire in the system to allow the stobe unit to be
withdrawn. We have found no problem at all in running new wires down the
conduits (same argument for the pitot / static tubing)
The flasher unit will be sited on the rear of the baggage bay bulkhead.
If this is of any use great. If you want any pics of particular parts of
the installation I can probably scrounge a digital camera.
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