Ron Wanttaja wrote in message . ..

Sorry for being late. I was busy during the last days so I couldn't
answer.

There are two main airworthiness categories: Standard and Special.

Standard airworthiness aircraft are proven to meet certain FAA standards, and
they must be maintained to ensure their continued compliance with those
standards. At given intervals they must be inspected to ensure they still
conform to the Type Certificate they receive. Since these aircraft are known
quantities, they may be placed into commercial service with no further FAA
certification action (although some additional equipment may be required for
some operation).

Standard airworthiness includes normal, aerobatic, utility, transport, commuter,
and transport categories.

Special airworthiness is used for airplanes that either have not undergone the
FAA certification process, or specific changes are made to them that take them
outside the limits established by their type certificate. Operation of Special
airworthiness aircraft is basically governed on a *per aircraft* basis. The FAA
assigns operations limitations to each aircraft, and these limitation are not
blanket to a given aircraft type nor are they transferrable to an identical
aircraft.

Ok. So that means if I build a kitplane and get an airworthiness
certificate this doesn't necessarily mean that my neighbour building
the exactly same kit with exactly the same parts. Understandable, as
even with the same parts the quality of work may differ.

Special airworthiness categories include Limited, Primary, Restricted, Special
Light Sport, and Experimental. Commercial operations are *not* prohibited, but
they require specific FAA approval. The degree to which the FAA grants such
permission varies.

Ok. So if I want to use my experimental commercially I need to get FAA
approval first.

The Experimental category under the Special Airworthiness includes a number of
categories, such as racing, market survey, R&D, Exhibition, experimental LSA,
and amateur-built.

Racing is clear. What is the difference between the other categories?
I assume amateur-built means a plane built by hobbyists. R&D probably
is something like an experimental airplane from a plane manufacturer
like the YF-22, right? What is experimental LSA?

I also wonder when a plane is amateur-built. I assume it's the case if
someone without special knowledge builts a plane by itself. What about
if he does that commercially (building planes and selling them)? Or
what about if a aircraft construction engineer builds a plane? He
probably can't be considered as amateur?

The FAA's *policy* may be to deny permission for these
aircraft to operate commercially, but such policies can be waived. You just
have to give the FAA a good reason why the waiver is a good idea.

So in the end that means it's basically not allowed to use them
commercially, but this can be overcome by a waiver.

As others have described very nicely, the L-39 Albatross may be a safe,
professionally-designed aircraft, but it never was awarded a US type
certificate, nor any similar type certificate that the US is treaty-bound to
honor. Hence, it can never be operated normal or any other Standard category.
That tosses it into the Special airworthiness category, and the category it
apparently best fits into the Experimental/Exhibition one.

I understand.

Obviously, with dozens L-39s being imported to the US, having a school that can
check folks out in them is a real good idea. So the FAA will issue a waiver
allowing them to operate one or several aircraft to train folks. Similarly,
having a school for training civilian test pilots is also beneficial to
aviation, hence a waiver was possible. Similarly, manufacturers of
high-performance homebuilts have received waivers allowing them to provide
training in a company-built example.

I understand

The FAA waiver usually demands that these planes receive professional-type
maintenance similar to that of standard airworthiness aircraft (e.g., the L-39
instructor won't be allowed the maintain the plane himself unless he has an A&P
license).


So basically if You maintain Your plane according to the manufacturer
standards and if You have a valid reason chances are good that You can
get a waiver to allow commercial operation.

Thank You very much for your very detailed explanation. And of course
to everyone here that answered to my (probably somehwat stupid)
questions.

JJ.