Ok.. multiple questions.,. and I will do my best to answer most of them...

John D. Abrahms wrote:
Hello!

I'm reading here for a while now, but today I want to come up with a
question that bothered me for a while. I'm not a pilot (but will begin
to take flight lessons soon) so this is mostly out of curiosity.

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.

Ok.. correct. They are considered "Experimental - Amatuer Built". They
can be one of a kind, unique designs, or they can be "one-off" copies of
existing plans-built or kit-built designs.

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

Not quite the case. THere are several certified, Normal Category
aircraft out there that are composite construction. Lancair has a
factory built product, and Cirrus is actually the best selling factory
built GA airplane in the world based on last years sales figures. They
are making more airframes than any Cessna model.

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. I now wonder
why it's treated as experimental, and not as a normal aircplane,
utility aircraft or aerobatic airplane.

It is listed as an Experimental because it does not have an FAA issued
Type Certificate in the Normal, Utility or Aerobatic categories. The
manufacturer did not pursue certification testing to obtain this status.

Why is this the case? What
makes a jet airplane that is produced by a factory in high numbers
different than say a C-152 that also is produced by a factory in high
numbers? Is the only way to register jet airplanes like the L-39 the
experimental category? Or can they also be registered as say aerobatic
aircraft?

Unless formal certification is undertaken, by the manufacturer of the
airframe, then the answer is no. I doubt that will be forthcoming, since
the former Warsaw Pact countries are able to sell their surplus old jets
just fine. Although they are listed as "Experimental" they are NOT
amatuer built, and the rules they operate under (Exhibition, I believe)
are somewhat more restrictive than your typical homebuilt (once the
homebuilt is out of phase 1 testing). Certification will involve LOTS of
money, time and NEW airframes (some are tested to destruction..)



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. What if the L-39 would not be registered as
experimental but as normal/utility/aerobatic airplane? Would this also
require 1000hrs of PIC time before someone can fly with this L-39? Are
there any PIC hours required to be allowed to fly turbine airplanes?
Or are the 1000hrs required for experimental airplanes in general?

For the short term, normal/utility/aerobatic cert isn't gonna happen. IF
it was, then the airplane would fall under the "Large or Turbine
Powered" part of CFR 14, part 91. I want to say (without looking it up
right now) that large or turbine powered aircraft require a type rating.
This is easily summarized (and probably over simplified) as a checkride
to ATP standards in the aircraft (and ATP candidates require over 1200
hours to begin with), and a comprehensive understanding of the aircraft
and all its systems. The LOA process is essentially a "waiver" to the
type rating process, since the airplane doesn't have a "type
certificate" against which the rating can be issued. LOA's are not
something I have experience with, and I may be mistaken on the details
here. The list here WILL correct me if I'm wrong.. I'm sure.


I also heard that it's not possible to use an experimental plane for
training (PPL, CPL, IFR, whatever). Is that true? If so, registering
airplanes like an L-39 in normal/utility/aerobatic category would
probably also remove some limitations like the use for training,
right? So why are they registered as experimental instead?

You CAN use an experimental plane for training. It just cannot be used
for commercial purposes. So, if someone wants to TEACH you for free in
their's or someone elses experimental, they can. THey cannot charge you
rent, and if it was your plane, you couldn't hold the airframe out for
hire. A new exception/waiver that is in place now is that "transition
training" is now available for the Factory and lay CFI's to provide
training in type to prospective and new owners of experimental airplanes
.. For instance, before I take flight in the Velocity that I am helping
build, I will travel to Florida and recieve legal instruction (for a
fee) in a factory sponsored/operated/built aircraft.

As I said, it's just curiosity. But it really confuses me.

JJ

It confuses a lot of people, and we will find out shortly if I've got it
right, too.

Dave