I had a chance to stop by this afternoon and examine the cracked support
bracket for myself. It's a small triangular sheet aluminum bracket (maybe 6"
long and 3" wide -- imagine a 90 degree right triangle with a flange bent
over along the hypotenuse, and with a small hole drilled near the 90 degree
point for the bellcrank bolt). It supports the top of the bellcrank pivot
bolt (via the hole at the bracket's apex). The bellcrank bolt extends
throught the hole in the bracket, thorugh the bellcrank and then through the
lower wing skin. A nut on the end, outside the wing, completes the
assembly. The bracket had cracked along the horizontal flange where it is
riveted to the adjacent wing rib. There are six rivets holding this flange
to the rib. There is also a vertical reinforcement piece (another, smaller
triangular piece) that is riveted to the bracket, that has another three
rivets into the rib, so there are a total of nine rivets holding the bracket
to the rib. The crack was behind the most forward rivet and is about 3/4"
long.

Steve (our A&P) says that after it cracks near that first rivet, the crack
will propagate along the bend that forms the flange until it reaches the
next rivet, then the next, etc. The aileron will get progressively more
"spongy" feeling as this happens. However, unless it's allowed to go
unrepaired for some time, it seems unlikely that there will be a
catastrophic failure. We caught ours early (Steve noticed that the bracket
was moving when he moved the aileron). Nevertheless, it needed repairing,
which involves removing the fuel tank, drilling out the nine rivets, and
replacing the bracket. He was almost finished when I stopped in at 3:30, so
it shouldn't be horrendously expensive. Steve adds a small doubler to the
factory part, which adds a bit of extra metal thickness to the first two
rivets and which should reduce the likelihood of it happening again. He says
this cracking occurs from the ailerons banging against their stops, so
anyone who has a Cherokee needs to make sure the gust lock is in place when
the plane is tied down, every time.

--
Bob (Chief Pilot, White Knuckle Airways)