you mean this sub-thread, (which seems to live on even though it is insignificant in its contribution)
Relative to the engine Uncontained Hazard
The regulatory requirements treat this against a statistical threat, i.e. like weather, birs, ice, etal. its impossible to protect against all threats so it accepts a level of protection that history has demonstrated does not significantly contribute to risk of a catastrophic outcome compared to all other threats.in total
It basically looks at "lessons learned" (from history) and design protections that have worked in the past i.e. redundancy, separation and shielding.
Adding to the historical experience are some field tests of small fragment penetrations of actual aircraft structure to define residual energies and the liklihood of defeating the design protections.
The FAA typically take the most simplistic approach of determining compliance against their pocket lists of what is typically used in other designs, without any detailed analysis of energies, fragment sizes or shielding robustness. While the engine installer looks at a very complex analysis akin to what is used in the military to assess vulnerability against hazards in a hostile environment.
As I hinted in an earlier post, the B737max issue of larger overhanging engines threatening the aircraft from a vulnerability standpoint is burred in the minutiae and only dilutes the original thread subject