Robin wrote:

Hello Paul,

    I hope this doesn't immediately sound like a dumb question, but how

can you find out exactly what the particular specifications for any given
"AN" part is?  For instance:  Metallurgist typically say there is just
about no difference between an American made grade 8 bolt and an AN
bolt.  Well, that's fine and dandy and we all can see that relationship
pretty well when you're talking about common fasteners,  but what happens
when you begin to talk about other products?  How can you really make a
sound comparison?

    Let's face it, we're building experimental airplanes and we do a

lot of things that wouldn't make muster for what we consider "AN"

standards.

Robin

  I see a lot of "aircraft quality" stuff on factory built spam that would
make your hair stand on end. So I'm not particularly convinced that because
a factory or an A&P says that something meets "aircraft standards" that it
would also meet my standards.

  Seems to me that much of the stuff that you see these days on factory
built aircraft has evolved as a result of real world experience over the
past 50 years. But that is based on experience with horizontally opposed
recips and who is to say that those accepted practices and standards are
necessary or even appropriate on our rotary engine applications?

Mike Wills

Some aircraft stuff is not too good, but mostly the detail stuff has cost
somebody
a lot of money to learn or in many cases, their lives.  Go to school on a good
Cessna or Piper engine installation.   Try to actually SEE how they did
stuff and
think of WHY.   There ARE other and ocassionally better solutions, and Paul
has pointed out a lot of them, but a lot of pretty smart people have worked a
long time to come up with stuff that works, and about 90% of it is a good
idea.
The trick is to find the 10% that you can make safer.  Don't let this suppress
good ideas, but at least start by learning what the std practice is.  A lot of
homebuilders have never sat down and really looked at a few certified
engine installations in real detail.  Everyone on this NL should.

AN stuff is all MS now, and the specs are available.  We access this on a
subscription web site at work, so I don't know how to do it otherwise, but
it is a
govt spec and should be available.  I look this stuff periodically the time
for my
"real job", where we are REALLY, REALLY, REALLY worried about
realiability.  MS is a pretty darned good starting place, but is not necessarily
the ultimate answer.

Bill Freeman

 
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