Hi Hartmut,
Comments interspersed below.
Regards,
WRB
On Sep 27, 2009, at 05:11, Hartmut Beil wrote:
William, all
From what I understand right now, there are authorized and
non-authorized holes.
Only in the mind of one or more FAA representatives. Structurally
speaking, holes are holes. No more, no less.
Authorized holes are defined in the factory drawings.
Agreed. But there are more one set of factory drawings applicable to
the wing spar and spar cap of the various models.
The one for the 415 series is available here.
http://www.ercoupe.info/uploads/Main/drawings/a-544.jpg
Two holes right in the center of the spar , each 4 holes holding
frame C and the all the holes for the tanks and the walkway.
Any other holes should be authorized per 337 or STC if there is such
STC.
If the FAA wants to make that argument let them. I think APOA and all
the type clubs can successfully counter that argument in the regulatory
process so as to blunt the effect if not entirely thwart it. It
certainly is not one exclusive to the Ercoupe. I don't think it is
appropriate for us to make that argument for the FAA.
The same is true for later models, where extra holes for seat and
trim installations might have been added. Any other holes beyond that
should be authorized to be legal.
See answer above.
The request Mr. Caldwell was making was regarding the existence of
some other unauthorized holes in the upper spar caps of the center
spar.
Mr. Caldwell is a solicitor and coordinator of comments on behalf of
the FAA. I don't think he originated "safety recommendation 09.087,
which we have not yet seen; and which is the catalyst behind this ACS
(which may or may not have been authored by Mr. Caldwell.
Due to our noise, it should be clear now even to the guys at Univair
that there are spars out there that had modifications that included
drilling holes.
This alone is worth an AD, where any plane with unauthorized
modifications to the main spar including holes will be grounded.
I respectly disagree. The complete wing structure must have the
capacity to carry in-flight loads as set forth in CAR 04. There is a
considerable safety factor included and specified. If Fred Weick
designed a spar that was TWICE as strong as CAR 04 requires, holes
decreasing the strength of such a spar are none of the FAA's business
until and unless said holes can be shown to reduce the composite
strength of a complete, assembled and covered wing assembly below the
regulatory strength requirement.
Now to the authorized installations. If the holes drilled for such
installations followed the pattern that the alons were using, they
should pose no danger, but if holes were drilled through the spar caps
extrusion more toward the edge I'd say it effects structural integrity
and is a matter of concern.
OK, but this is a "what if" argument. If the FAA has a "problem" with
SPECIFIC holes, let them identify those holes and everyone can look at
answering JUST THAT problem. The "improper maintenance" or
"unauthorized holes" brushes are too broad. A number of coupes that
could be shown by load testing to be perfectly airworthy could have
their airworthiness brought into question without the slightest
evidence of a genuine issue of safety.
So what can we do?
We can speak with strong and common voice that no one cares, at the end
of the day, as to "what if" FAA concerns. What is important, and
should be their focus, as well as ours, is resolving any genuine safety
issue as can be shown to exist. It is up to the FAA at present to make
that showing beyond the "cause I said so" level of argument.
In our last AD that covered the center section, we made our voice
heard and arranged that the center section can be checked with the
wings of method or a boroscope.
Mr. Caldwell suggests amending to this AD. We should give
reasonable advice on how this amendment will look like.
1. First , no extra holes , no further action
2. Extra holes, documented - verify that it follows an approved
pattern
3. Extra holes, not documented - certify if it follows the approved
number and pattern
4. Extra holes not following an approved pattern or number. Replace
spar cap or add stiffener provided by Univair ( has to be developed)
Hartmut
And, again, I believe any AD action, being applicable to the center
section and not the outer panels and looking for holes and not
corrosion, should be entirely new. Remember, the FAA has yet to
demonstrate that "unauthorized maintenance holes" in any way
precipitated or contributed to this single obvious overstress failure.
The private ownership of aircraft would swiftly become financially
impossible if the FAA is permitted BY WE, THE PEOPLE to issue an AD
every time a plane crashes and they aren't sure why. Then, all they
have to do is point at an aircraft type and make all owners of that
type aircraft do their work for them.
That's not why they are there. The power they have is supposed to be
used in the public interest in the context of US being the public and
not THEM.
SIncerely,
WRB
