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Corrosion discovered in brackets
From CP86, Page4 (October, 1996)
A Long-EZ pilot has reported finding
moderate to severe corrosion in the elevator hinge brackets on his GU canard. He did
not build this airplane, and the history of this airplane is not known, but it currently
is based on the East Coast in a salt water environment and the corrosion was significant
enough to cause this pilot to dig out all of the hinge brackets and replace them.
We have not found anything like this on any of our aircraft, but keep in mind all of the EZ types here in Mojave live in hangars and in a dry desert environment. We will continue to investigate this problem, and will report in future CPs. Every EZ and Defiant owner should make frequent careful inspections of these hinge brackets. Keep in mind that there was little or no evidence visible outside the canard. The corrosion took place inside the canard, where the bracket was floxed into place in the high density foam insert. Probably moisture was "wicked" up into the flox/high density foam and was trapped in close proximity to the 2024-T3 aluminum brackets.
What can be done to prevent such an Occurrence? The best thing to do for these brackets, and all other aluminum parts, is to treat the bare aluminum with Alodine 1201, after Pre-Cleaning with Alumiprep 33, prior to installation. They should then be sealed in pure epoxy prior to bonding them into the canard. We plan to do surgery on Burt's Defiant canard, which was built in 1978, and we will report on the findings in CP 87.
We would appreciate hearing from anyone who may find corrosion in this or any other area. Feedback from builder/flyers is extremely important and is our main source of information relating to safety.