C wrote:
: Hi folks,

: I ran into a little problem today.

problem snipped

This is probably due to someone torqueing the wing forward or aft at
some point. The wing flexes around the main spar and pulls or pushes on
the rear attatch fitting. This causes a crack in the spar carry through
right where yours is. The wing is 12' long, so even a small torque
applied at the tip gets "amplified" by the long lever arm.

The front attatch fitting is there really to hold on the leading edge
"glove" and doesn't take much force.

The main spar and rear attatch take all of the loads.

Hard landings cause cracks in the wing lower skins at the most inboard
point just in front of the main spar, which is covered by the long metal
fairing when assembled. Ripples on the lower aft wing skins also show up.
If this was done during a hard landing it was really a doozie.

My Cherokee 180 had similar damage on the left wing rear attatch fitting.
It was apparently damaged in 1969 when the left wing hit a runway light.
It was repaired without logs or 337's and went unnoticed until I bought it
in 2000. The mechanic that did the pre-buy found it. He said that it was
repaired just fine and not to worry unduly. Since the plane had 31 years and
5600 hours since the repair I think it is just fine, too. I don't believe
that there was a crack in the spar carry through on my plane, though.

The repair on my airplane involved cutting out the baggage compartment floor
about 6" aft of the rear spar carry through. The rear spar carry through
was replaced, picking up the rivets in the steel plate. A scab patch was
put on the outside of the fuselage. The baggage comp. floor was replaced
with a doubler on the inside along the cut line. It all was beautifully done.

If I can ever get over to the airport again, which may not be for 2-3 more
weeks, I can take some pictures if you wish.

--
Aaron Coolidge