Spar Butt cracks

P

pitts2b

New member
I ran across this wing this past weekend and was wondering how to go about the repair on this spar. Cracks in the butt of the spar. If anyone has any experience i would appreciate hearing from you. Having trouble posting pictures on here so please use the link below. Thanks.
Blue skies
Nelson
http://viewmorepics.myspace.com/index.cfm?fuseaction=viewImage&friendID=170657919&albumID=478278&imageID=32316526



index.cfm
 
I think the fix is to cover it with a thick tarlike paint (Out of sight-out of mind). It looks like "checking" and isn't as ominous as cracking. Insert paper to see how deep the checks go. I'm sure someone more knowledgeable than I will give advice. Listen to experts, but don't get too upset yet.
 
So far, I don't see much wrong with the wood. I'd use very thin lockwire....020 or less to gauge the depth. Don't be surprised to measure 2-3 inches. I'd clean the surface and coat with 3-4 coats of epoxy varnish. Also, check the spar straps and bolts for corrosion. Dan
 
I agree with Dan, thoes are not "cracks" but "checks" in the wood. This type club sells a booklet called B10-011 "Low Wing Wood Inspection" . It tells ya what a crack is. The limit on a crack is if it extends beyond the second bolt hole. Your spar looks like new.
 
Thanks for the information. The cracks, I mean Checks were easy to spot, but before I decide to buy or not, what are some of the less obvious things too look at? Thanks again for everyones input.
Blue Skies,
Nelson
 
According to Bellanca Engineering Report BER 838 the aft spar can have checking cracks out to the second bolthole in the areas of the wing hinge straps and up to five inches in depth between the hinge straps. The forward spar is more critical with checking cracks allowed only to the first bolt hole in the areas of the upper hinge straps and and no checking cracks allowed in the areas of the lower hinge straps. I can't remember how deep the cracking can be between the straps on the forward spar. I checked mine with a very thin blade of dry grass that would slide deep into the cracks. All my spars passed the inspection. BER 838 goes on to advise packing the cracks with waterproof aircraft glue (that would be Resorcinol) and sealing the ends of the spars with 3M fuel tank sealant. This sealant is no longer manufactured but is of the same mil spec as Pro-Seal 890B. That's what Alexandria uses these days. I packed the cracks with Resorcinol but I elected not to use the fuel tank sealer because it is opaque and will make future inspections of the spar butts impossible. I chose instead to coat the spar butts with three coats of epoxy varnish. A copy of BER 838 can be obtained from Alexandria Aircraft.
 
I was in the wing shop of Alexandria Aviation yesterday and Randy was working on a wing that had a huge crack in it. They were able to run a cable tie into it 18 inches so he was cutting out part of the spar and replacing it. The puprose of covering the end of the spar with whatever you choose to use is to prevent it from drying out. When I bought my bird they checked the wings which looked great and they had me seal the spars right away.
Gary
 
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