[tappaseater]

It reminds of the story of the de Havilland Comet, which had a bad habit of breaking up in mid-air. Engineers submerged the fuselage of the plane in and out of deep water to simulate pressure changes and it finally failed. leading to the diagnosis of metal fatigue. I mean that was 70 years ago. You'd think it might have crossed his mind.

[pengaru]

I think aluminum is much better understood as having effectively no endurance fatigue limit [0] in that its threshold keeps dropping as the cycles progress.

It's expected for cracks to form in aluminum parts of such planes, IIRC they're X-Ray'd on a schedule to discover cracks and replace the relevant parts.

I don't know if CF is expected to behave similarly. You certainly don't see it as an obvious quality of CF bicycle frames, as is visible with aluminum frames. The aluminum bikes have such thick beefy tubes and harsh/rigid ride quality to eliminate crack-forming cyclic stresses. CF bikes are considered more comfortable since they don't have to prevent all the flex, as well as being lighter.

[0] https://en.wikipedia.org/wiki/File:S-N_curves.PNG