Destructive test on long

[LargePrime]

I took this from the COZY builders mailing list. I thought it interesting enough to post.

 

Posted by Marc J. Zeitlin

 

Terry L Schubert forwarded this message - although the main part of it does NOT apply to COZY's, some does, and the rest is still interesting:

 

I just got a call from Mike Melvill with an update on the Vari-Eze spar situation. He has completed the destructive testing of Ernie Joiner's Vari-Eze. Ernie kindly donated his 21 year old Vari-Eze to determine real life G limits of a typical Vari-Eze. It was based at Santa Maria, CA near the Pacific Ocean. We all owe that man a debt of gratitude for his generosity. We also owe Burt and Mike for setting up such a destructive test and taking the time to assure our safety many years after plan sales has ceased.

 

The good news is that the winglet to wing attachments held up way beyond ultimate failure loads. The test wing spar caps had no joggle, which suggests the joggle on the East Coast failure aircraft was caused by poor workmanship and not design error. The aluminum spar cap plates had slight corrosion, but nothing to cause great concern. The canard failed at 8.3 Gs and the wings failed at only 7.0 Gs. Those numbers are less than expected. Burt was out today so no comment was available as to contributing causes. Mike said he'd not exceed 3.5 Gs in any Vari-Eze he might fly.

 

An unexpected development was discovery of extremely corroded attach bolts that hold the canopy and the rudder cable bellcrank brackets to the firewall. The canopy hinge attach bolts were necked by corrosion down to 1/16" diameter with no clue on the visible parts of the bolts. It is recommended you remove one bolt at a time and replace with new. Be sure to take appropriate corrosion proofing steps for the bolts that penetrate the wood longerons and the firewall. The wood holds moisture and will cause corrosion to through bolts.

 

The bolt corrosion issue effects Vari-Eze, Long-EZ, Cozy, Cosy Classic, AeroCanard, Cozy MK-IV, E-Racer, Defiant and any other similar design. More information will be in the next Central States Association Newsletter.

 

Please notify builders who may not be CSA members or may not be connected to the net so they may take corrosion proofing action during construction.

 

Terry Schubert

Editor

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