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Thanks, Jan Zanutto, for a very informative input re SB 32.
Don Bowen
[EMAIL PROTECTED]
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From: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
Reply-To: "[EMAIL PROTECTED]" <[EMAIL PROTECTED]>
To: [email protected]
Subject: [COUPERS-TECH] SB31 findings today
Date: Fri, 10 Feb 2006 00:36:05 GMT
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I found out a couple of things today relating to this. I knew about the
crash but didnt realize that one of my friends at the Fresno FSDO office was
the one who investigated the accident- he was there to see the 2 dead bodies
in the wreckage. What he said that he saw on the wing center section was
that it "opened up like a zipper" along the rivet lines; that some of the
upper and lower rivets that attach the spar caps to the webbing were sheared
off internally due to corrosion and had been that way for a while. He spoke
to the IA who did the previous annual and externally (from inside the wing)
it looked pristine. Corrosion inside the cap and web joint had weakened some
of the rivets, once those sheared then there was a chain reaction. We are
pretty certain that the kid was doing aerobatics- the FAA engineer who
helped said that without the extra stress of aerobatics it still would have
eventually happened as corrosion ate away the rivets from the inside.
The inspection is purely voluntary- the type certificate holder is not a
regulatory agency and cannot impose a mandatory inspection on the owner.
HOWEVER; the FAA inspector told me that if they feel the need, they can
revise the existing center section AD to just include a reference to the
SB31 and then it's mandatory.
So I talked to my supervising Level III ultrasonic inspector (I am a level
II) today and we discussed how to set up the machine, etc and what
calibration standards to use. I am planning on doing my coupe once our U.T.
machine comes back from the calibration lab. The inspection checks the
rivets to see if they are 100% intact or are sheared somewhere in the middle
(which is what they found on the wreckage). It involves touching the probe
to each rivet bucked head inside the wing and observing the readout. An easy
process- but it involves pulling wings and interior. The only challange will
be sticking my arm all the way inside the center section to reach the ones
farthest in. It's probably going to take about an hour per side just to do
the inspection, once everything is opened up. We'll see how far off I am on
that time estimate. As far as cost- it wont cost me anything, just my time.
I do know that in the past we have paid some Ultrasonic inspectors to come
out and do our fleet of EMB120's for a special inspection and it was
$1500.00 per airplane.
IF this thing goes AD then we can talk about doing some here in Fresno. As
long as the owner helps pull the wings, etc there will only be a very
nominal charge just to make it worth my time coming in to work on a
saturday. I practially live there anyway...
Jan Zanutto
Fresno, CA
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