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One possible problem with bonding vs. fasteners is crack propagation. If you have a small crack in a bondline it can grow under stress. One advantage to fasteners is that a small localized failure tends to remain localized if the fasteners are properly sized and spaced.

In commercial aircraft you will often see metal bonding in primary load carrying structures. The bond is often backed up with a few fasteners "just in case". These fasteners are affectionately known as "chicken rivets".

I've never looked closely at the structure of the aft pressure bulkhead on a -4P but I would imagine that a failure of this bulkhead might interfere with rudder and elevator controls? I wouldn't want to risk it if that is the case.

Paul Klusman

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Please send your photos and drawings to marvkaye@olsusa.com.