Originally Posted by
Tangoer
Just like a Boeing 787?
No - these are sandwich panels with a honeycomb core, much like a ski. They are very stiff, but not very resistant to sharp local loads as the skins can perforate easily. Also, because of the thin skins on the panels, they are susceptible to fluid ingression into the core which can then lead to delamination and core degradation etc.,...
B787 (and A350) are in the largest part made of monolithic (solid) carbon fibre/epoxy laminate structures, which can take local loads/failures much better, and certainly in fatigue (cf Southwest 737 skin failure this week). On the external structure there will be some sandwich panel structures (e.g. main landing gear doors, rudder, etc.,) but none are primary structure (cf rudder coming off Air Transat Airbus a few years ago).
I would guess that the floor panel failing is not a flight critical issue, but kudos to AC for taking the plane out of service when discovered on the ground.