Quote:
Originally Posted by Ralph Inkster
Interesting joggle around the edges of those cover plates Dan. Advantages of doing this?
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The polysulfide sealant specification includes a basic minimum test elongation of 200%. The standard is as low as 75% when tested in adverse conditions.
Let's use 200%, and assume a no-joggle riveted overlap joint with a 0.001" sealant thickness. Apply a shear load. If the strain displaces the two components by more than 0.002", the sealant line is subject to adhesive or cohesive failure.
Increasing the thickness of the sealant line in the fay surface boosts the capacity for displacement...so just add an outboard joggle.
BTW, warm fuel is one of the adverse conditions. And most readers will be surprised to learn
there is no polysulfide standard for resistance to avgas. The test fluid is AMS2629:
https://www.sae.org/standards/content/ams2629/
The good news is that most sealant batches test at 300% or more. The joggle is easy insurance.