The general idea is to make the attachment of the plywood servo box more secure to the wing's structural foam.

Most of us put epoxy into all the interior joints of the servo box, and work some down the outside of the box between the plywood and the foam.

These boxes have come loose on a number of R70s, particularly those that are flown hard. Losing an aileron is not quite as bad as losing an elevator, but can certainly cause a crash.

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I just missed Mike's post above, which is more informative with pictures.