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From: doug@terak.UUCP (Doug Pardee)
Newsgroups: net.aviation
Subject: Re: LearFan Certification
Message-ID: <281@terak.UUCP>
Date: Tue, 22-Jan-85 19:38:49 EST
Article-I.D.: terak.281
Posted: Tue Jan 22 19:38:49 1985
Date-Received: Fri, 25-Jan-85 21:53:24 EST
References: <19504@lanl.ARPA>
Distribution: net
Organization: Terak Corporation, Scottsdale, AZ, USA
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> Now lets add the certification cost: what is it these days?  $10 - $50
> million?  I seem to remember that Lear Fan had spent over $100 million
> for certification - which it hasn't got yet.

The LearFan is certified under a lot more restrictive rules, being a
large, turbine-powered airplane.  Further, the LearFan is a good
example of certification *working*.  Turns out that the original
"light weight" design of the fuselage was totally unsuitable for
a pressurized turbine-powered plane.  It failed the original
test (broke in two), and a new cabin, with a fix, was built.

That cabin ALSO failed, and the fuselage had to be totally redesigned
from scratch (and the new fuselage built) in order to be safe.

History lesson:  The DeHavilland DH-106 Comet-I was the first jet
airliner, put into service on England's "Empire routes" in May, 1952.
One year later, one "exploded" in mid-air.  Over the next year,
two more were lost with all aboard.  One is known to have "exploded"
in mid-air, the other thought so, but it could have been destroyed
by a monsoon.  In all, 3 of the 9 Comet-I's were lost in one year.

Fortunately, the DeHavilland people didn't just give up and scrap
the Comet-I.  It took them a very long time, but they finally learned
the cause:  metal fatigue from the pressurize/depressurize cycle at
the previously unheard-of altitudes that the Comet-I flew at.

So now we know better, and have strength requirements for pressurized
turbine-powered planes.
-- 
Doug Pardee -- Terak Corp. -- !{hao,ihnp4,decvax}!noao!terak!doug