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 _________________________________________________________________ More than messages–check out the rest of the Windows Live™. http://www.microsoft.com/windows/windowslive/
