"Marco Rispoli" wrote
(Yes i am looking into Tomahawks ... I am aware of the reputation they
have).

There's nothing wrong with Tomahawks. Even their most ardent
detractors only claim that they have a problem when spun (my
experience with spinning them, as well as FAA tests, indicate these
problems are imaginary) and in any case, lots of airpcraft can't be
spun safely, which doesn't make them bad airpcraft. I've never owned
an aircraft that could be spun safely.

My question is, from this text it looks like planes... "expire". Once the
airframe is past a certain number of hours, that's it. They are toast.

That depends on the airplane. Airplanes certified under the old CAR-3
regulations were not required to show/estimate a service life for most
airframe components. Everything was on-condition. Because of
grandfathering, lots of airplanes are still being built to those old
regulations with only minor changes. That includes all the new Cessna
singles and most Pipers, Beeches, and Mooneys, for example.

This made a certain amount of sense back in the tube-and-fabric days.
Steel doesn't have a practical fatigue life. As long as you don't
overstrees it and it doesn't rust, it will pretty much last forever.
Fabric was always an on-condition item. Wood has its own special
problems - it seems to last forever when taken care of, but glues give
- and are hard to inspect.

Airplanes that were clean-sheet designs under FAR 23 usually have
airframe component limitations. Same for the JAR certified stuff.

You need to realize that aluminum airplanes don't last forever anyway.
Aluminum has a fatigue life. That's not a big deal for most of the
airplane, since most of the skin is sized more for handling
requirements than structural integrity, but that's not the case with
spars. You should not expect Aluminum spars to last forever.

On the other hand, 11,000 hours for the Tommy was overly conservative
and of course now that many of them are reaching that number of hours,
an STC to increase that is available. That's how it generally goes
with life-limited components - if the initial estimate is overly
conservative and time starts running out with most of them in good
shape, someone comes along and gets an STC to extend the component
life.

A 10,000 hour Aluminum GA airframe is OLD. It may still be OK, but
most of them are not. Even if the Aluminum itself is still OK (it is
often showing signs of corrosion, cracks, and many working rivets) you
still have the issues of old and many-times-flexed wiring, pulleys,
cables, clamps, and all the other stuff. Can all these things be
repaired/replaced? Sure, but it takes time and money. A 10,000 hour
airframe is rarely a bargain.

You have kits to prolong their life (for the Tomahawk at least, as I have
seen) but ... what happens after the life goes past that threshold?

If it's still in good shape, there will be another kit.

Michael