On Thu, 16 Dec 2004 15:04:55 GMT, Bill Daniels wrote:

"T o d d P a t t i s t" wrote in
message ...
John Giddy wrote:

Wasn't there a fatal just a few years ago where one of the wing pins
in a DGsomething came out because the safety latch became
delaminated from the inside of the fuselage? Wing flexure in rough
conditions caused the pin to work out, as I remember.

A DG400 lost its wings a few years ago. It was piloted by
Fred Jacobs and at an age when most of us have been retired
for 10-20 years, he successfully made his first parachute
jump when the wings decided to depart. Delamination of the
safety latch was suspected, but I don't think anyone knows
for sure.


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 !!!
The main pin in gliders like the Nimbus, Std Cirrus etc. is under
strong continuous shear load in flight in calm air. However in severe
turbulence, I can envisage the load reversing frequently, and with a
small amount of fore and aft movement, "walking" the pin out.
The DG uses two large pins in shear to connect the wings, with no pins
in the ends of the spars. Only a single spar extension on each wing
which overlaps the other for the joint, so such "walking" of a pin is
probably more likely than with the Schempp-Hirth design which uses a
forked end on one spar end and a single end on the other with a pin to
locate its tip in the opposite root rib.
Please always use a safety pin !
Cheers, John G.