As I recall, there was just such an accident back in the early '70s at
Minden, NV during the U.S. Nationals. During a high-speed starting run,
both wing pins worked their way out and the wings departed the glider,
turning the fuselage into a missle...from which the pilot bailed out
successfully. I could have my facts wrong (which might explain why no
one else has mentioned this) but I believe the cause was determined
(suspected?) to be the main wing pins not being safetied. One notable
thing was that not only was the pilot obviously at risk when this
happened but also numerous crews/spectators. At least one of the major
pieces hit the airport very close to the crowded takeoff line.

Chip Bearden
ASW 24 "JB"

"John Giddy" wrote in message
.. .
I started to write that I was dubious about the wing pins working
their
way
out since they would be locked in place by shear loads. Then I
thought
about it more.

For those gliders where the removable pins merely hold the wings
against
sliding out of the fuselage and the spar end spigot pins take the
actual
bending loads, there is no shear load on the removable pins.
They could
indeed work their way out.

My Nimbus uses a single 50mm diameter pin that does take shear
loads so
it's
hard to see it working out. However, I'll safety it anyway.

Bill Daniels

Bill, I hope that your grammar is confusing. I read your last
sentence
to indicate that you do not currently safety the main pin, but will
do
so in future. I hope I am wrong !!!

You are right. I've always safetied the main pin on the logic that
since
there's a bracket the designer must have thought it necessary. Not
something that calls for experimentation.

Bill Daniels