"John D. Abrahms" wrote in message
om...

I know that all the airplanes that people build by themselves fall
into the experimental category, because they are not factory-made,
serialized products but individually built with different quality and
with different modifications.

Not really. You can restore a certified airplane from a dataplate and a
single piece of metal and build everything yourself. If you can get an IA to
sign off on it, and the FAA to agree, it doesn't have to be experimental.

I also know that GA airplanes made of
composites usually fall into the experimental class category, too.

No. Cirrus, Lancair and a few others are composites and they are certified
aircraft.

What really annoyed me is that there also are planes that are not
composite and also are factory-made in high numbers that fall into
experiemnat category, like the Aero L-39 Jet airplane.

That's because it's an ex-military airplane that was never put through
normal certification. In order to fly in private hands it has to have an
experimental airworthiness certificate.

From what I know a pilot who wants to fly a L-39 jet airplane needs
1000hrs of PIC time, and after that needs a Letter of Authorization to
be able to fly the L-39.

Correct.

What if the L-39 would not be registered as
experimental but as normal/utility/aerobatic airplane?

The manufacturer, as far as I know, has no interest in spending the oodles
of money required to achieve this. And most likely you wouldn't be able to
afford the airplane if they did.

Would this also require 1000hrs of PIC time before someone can fly with
this L-39?

It would require a type rating.

Are there any PIC hours required to be allowed to fly turbine airplanes?

To my knowledge, that is only the case on the few ex-military experimentals
being sold out there.

I also heard that it's not possible to use an experimental plane for
training (PPL, CPL, IFR, whatever).

No. A CFI can use your experimental to train you to fly it.

Juan