Landing light location and wing mount

[Mike Kimball]

Some of you may remember that I questioned the list about the location of my
landing light and Wayne pointed out that it wasn't a good idea to put it
where I did. If you've got an exceptional memory you might remember I asked
the list ages ago about my wing attach fittings being right up against the
forward attach point on the fuselage instead of somewhere in between. I
posed those questions to Murphy technical and thought Darryl's reply might
be informative to others. I found it interesting that the spar is not the
issue. It's the break in the leading edge skin. A reminder that this kind
of structure is a stressed skin design, where the skin accounts for a
significant amount of the structural integrity.

Mike
044SR

P.S. I would also like to mention for the record that I have posed some
questions recently to Murphy technical and have been very pleased with their
timely and helpful responses, directly from Darryl in the most recent cases.

-----Original Message-----
From: Robin Dyck [mailto:rdyck@murphyair.com] On Behalf Of Murtech Mailbox
Sent: Monday, April 03, 2006 9:48 AM
To: Mike Kimball
Subject: RE: Landing light location and wing mount

Hi Mike

I hate to deliver the bad news but I think the light should be moved out
to one of the outer bays. The front spar is not the problem. The
problem is the leading edge which resists the torsion applied to the
wing. I can not say for certain that it is compromised with out a load
test but I can tell you that when doing the wing loading tests the
leading edge distorts considerably and with the cutout it might not
return to normal. My suggestion would be to put a 0.032" patch over the
cutout ensuring that a least one stringer top and bottom is picked up.
Make up a single spacer of aluminum with as large of diameter as you can
to replace the two Delrin spacers. Having one spacer will reduce the
bending load on the attach bolt.

Darryl



-----Original Message-----
From: Mike Kimball [mailto:mkimball@gci.net]
Sent: Sunday, April 02, 2006 10:01 PM
To: Murtech Mailbox
Subject: Landing light location and wing mount

I recently discovered that there may be an issue with where I mounted my
leading edge landing lights. I apparently wasn't paying enough
attention to the instructions and mounted your kit 5 bays outboard of where
the lift strut attaches. Apparently, it was supposed to be limited to
either the outermost bay, or one bay inside of that. Should I be concerned
with compromising the forward wing spar at the point where I mounted the
light?

Also, on a different topic, when I mounted my wings to build the lift
Struts I discovered that the forward spar attach point on the wing was
butted right up against the forward part of the fuselage attach point (the
square tube) when the rear attach point was in place. I expected the wing
attach to be somewhat centered in the square tube. Is this an issue or
should I simply put both delrin (I think they are delrin) spacers behind the
wing attach and not worry about it? Mine is a Super Rebel, not a Moose, and
I understand that the Super Rebel has the wing attaches fixed solidly with
the spacers.

Thanks.

Mike Kimball
044SR






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