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There have been flight accidents which involved structural failure after fast decompression of the cabin, like BOAC Flight 781.

I'm thinking about how decompression can destabilize or destroy the structure of a fuselage;

I would think that a hole pinched into the cabin wall of 1 cm diameter will just cause slow decompression over minutes.

I got the impression that creating a larger hole, like removing a door, can potentially cause severe failure of the fuselage in other places than the hole.

If that is the case: what makes a hole large enough to be dangerous?
And what is the mechanism making a large hole dangerous?

Or is it that the structural failure comes first, and decompression is just a salient symptom of it?

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    $\begingroup$ In the case of the Comets, the decompression was a result of the failure. Many aircraft have lost doors and survived. The problem normally stems from the door contacting something on the way out, e.g. hitting the tail surfaces. I don't recall ever hearing about decompression itself leading to the loss of an aircraft. The Hollywood myth of someone shooting a hole in the fuselage causing an immediate explosion is just that - a myth! $\endgroup$
    – Simon
    Jul 2, 2015 at 10:29
  • $\begingroup$ I thought in the cases of the Comets it was a small failure in the structure, causing decompression, which causes widespread structural damage in turn. $\endgroup$
    – Volker Siegel
    Jul 2, 2015 at 10:32
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    $\begingroup$ No, but the failure started with a small crack. Decompression and further damage went in parallel, and once decompression was complete, the load which tore the fuselage apart was gone. However, by this time, you had parts of the fuselage sticking out into the free stream, and this tore it apart completely. So dynamic pressure finished the job, not internal pressure. That just got it started. $\endgroup$
    – Peter Kämpf
    Jul 2, 2015 at 13:43

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Often it's the structural failure that results in decompression.

The comet (the aircraft in your example) was vulnerable to fatigue cracking that would propagate throughout the fuselage and compromise the structural integrity. Nowadays the fuselage is designed to stop such cracks from reaching further than the next spar and planes are retired when the number of cycles has reached the design limit.

There are factors to take into account when the vessel decompresses. If portions of the vessel are closed off from each other, then the pressure difference between those sections can exceed the tolerance of the divider and cause damage. This caused the floor to collapse when the cargo door blew off in Turkish Airlines Flight 981.

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    $\begingroup$ The Comets also had square windows which led to pressure hotspots in the corners which in turn led to the fatigue cracks. $\endgroup$
    – Simon
    Jul 2, 2015 at 15:04

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