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Jan.
Thank you for your findings.
I think that the 1500 Dollars are more likely for this kind of inspection,
provided the owner takes off the wings, tanks and window parts himself.
It makes for an expensive annual.
Do me a favor and ask your friend from the FSDO office what exactly he saw.
Did he see oxidation powder or not?
Is he qualified enough to make such statement. And how does that statement
match the one that the center section opened like a zipper?
If the rivets were able to elongate the holes in the spar caps and rip them
out "like a zipper" then they were not corroded and they did their job as
designed and the center spar was truly ripped apart due to overstress.
Statements like that from your friend are based on assumption and do more
harm than good. Since we don't have photographs or other significant data on
that accident, I recommend to rely on the factual data the NTSB is providing
and forget the anecdotal evidence some uneducated people might bring.
Hartmut
----- Original Message -----
From: <[EMAIL PROTECTED]>
To: <[email protected]>
Sent: Friday, February 10, 2006 1:36 AM
Subject: [COUPERS-TECH] SB31 findings today
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advice in this forum.]----
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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