Were there witnesses to the accident? It was "manuevering" ; but we
don't know if that was
gentle turns, acrobatics, or something in between. I'd feel a whole
lot better if I knew they
were exceeding the planes limits and my common sense.
Dan C
On Sep 21, 2009, at 4:50 AM, Hartmut Beil wrote:
Guys.
The Airworthiness Concern" is based of the Sebring inflight
breakup. This is a real issue and I don't want to talk this down.
I am rather interested in more data on what unauthorized holes
would incorporate. As we know, Alons have their seat mounts drilled
directly into the upper spar cap and at the same time even allow a
higher gross weight.
Univair should have the data on this , at least drawings and one
could conclude a certain structural strength from that.
If holes were drilled unauthorized, there should be a method to
determine whether these holes are similar to the alon spars or are
a danger to the aircraft.
At least I would expect a dye check of the affected areas to look
for cracks. Because I belive there must have been cracks first. The
main spar does not collapse like this.
If it would then I would not recommend flying any Alon anymore.
More data would allow a more constructive comment. I hope we will
get an answer from the FAA, especially Mr. Roger Caldwell.
Hartmut
http://www.ercoupe.info
To: [email protected]
From: [email protected]
Date: Mon, 21 Sep 2009 02:39:05 -0500
Subject: Re: [ercoupe-tech] Improper holes in spar cap
Hi Ed,
......
But we also must encourage responses to this "Airworthiness
Concern Sheet". I have been working on a very comprehensive one
for several days. I will send it both by email and U.S.P.S.
Certified Mail, Return Receipt requested; and then post it to
Tech. That makes it harder for the FAA to "lose" or ignore
comments (claim they did not get them). Everyone is welcome
reproduce any portion of it or incorporate any of my thoughts
expressed herein in their comments with the single exception of the
following:
Should any of us wish to engage in engineering evaluation, i will
share a letter dated 10/12/49 from ERCO's Thomas M. Mountjoy,
Assistant Chief Engineer, addressed to the British Joint Services
Mission in Washington, D.C. At that time a 415-CD was being
officially evaluated in England.
Airplane limit load factors
CAR 04 1260 lb. +4.58 (- not available)
CAR 03 1400 lb. +3.50 -1.40
Limit wing load factors
CAR 04 1260 lb. +4.64 -1.75
CAR 03 1400 lb. +3.59 -1.32
Ultimate load factor = 1.5 x limit load factor
And no, I'm not an engineer of any kind either ;<)
Regards,
William R. Bayne
.____|-(o)-|____.
(Copyright 2009)
--
On Sep 20, 2009, at 08:43, Ed Burkhead wrote:
One thought: It seems to me that holes in the upper spar cap would
most likely be a problem when pulling negative g’s, wouldn’t they?
Or, during extreme vibration (i.e. flutter)? I wouldn’t think
normal flying loads within the normal positive g limits would
strain the upper spar cap.
But, then, I’m not an engineer of any kind.
Are there appropriate non-destructive diagnostic means to inspect
for cracks in the spar cap? Dye penetrant? Portable x-ray?
Do we have any aeronautical engineers here?
Ed
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