"Capt.Doug" wrote in message
...
I tried to post some bitmap images with this but it didn't come up on my
server. Anyways..

Concerning the Chalks seaplane crash in Miami, fatigue features were
observed in the lower spar cap of the rear spar of the inboard end of the
right wing, bisecting 2 offset drilled holes.

D.

This scenario is almost the same scenario that killed a friend of mine in
his F8F Bearcat. As these old airplanes age, even with constant care, it's
extremely difficult to assess the actual wearing down process on a specific
spot taking accumulated stress over time.
Sooner or later, subjected to the dynamics involved with in-flight forces,
all parts will deteriorate as we all know.

Finding that "sweet spot" that defines total runout time for every piece of
an airplane can be a daunting task. You can inspect, you can magnaflux, you
can estimate a failure mode through a computer model, but in the end,
something can and usually will give somewhere.
What's insidious in all this is that when these failures happen, they come
in two different scenarios. The first is obvious; a total failure of a part
which is instantly catastrophic such as was the case with my friend's
Bearcat where the wing sheared off the airplane coming out of a normal loop
at normal g, or the failure of a minor part which isn't instantly
catastrophic, but however instantly changes the entire failure model for
parts down the line that are affected by the minor part's failure.
It's a tough call on these old airplanes, and something that will be talked
about and debated by those involved in flying older airplanes without
finding a definitive answer ad infinitum.
Total replacement of a part based on an estimated failure span is good, but
even with that in place, considering the astronomical cost of doing this,
flying these old airplanes past their projected airframe runout I think will
always be a crapshoot.
Dudley Henriques