Quote:
Originally posted by Ernie Martin
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I don't know what caused these rivets to slowly disintegrate (you could see the shaft of some, without the head, so it's not that someone forgot to replace them), but it merits a good look on your aircraft. And I wouldn't wait for the next annual -- I'd do it before the next flight.
Ernie
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Those rivets originally installed by Cessna are "A" suffix rivets, which mean that the alloy is 1100 aluminum. This means that the rivets are dead soft aluminum, not alloyed with copper, so they have no structural shear strength at all. This is common to join aluminum sheet with fiberglass in order to not damage the fiberglass when the rivet is set. It doesn't take nearly the same effort to set the bucktail on an 1100 as it does a 2117 (structural) rivet.
This is a common occurance on an aging aircraft and deserves special attention on routine shop visits.
As the Skymasters age, the inspection techniques used 30 years ago need to be augmented to account for this aging.