Interestingly the FAA has stated that if any of these three conditions occur it will NOT require an investigation as proposed by #SpaceX. Cutting a lot of red tape it seems which is great to see.
"The three approved exceptions include:
failure of the thermal shield during high-heating;
the flap system is unable to provide sufficient control under high dynamic pressure;
and the failure of the Raptor engine system during the landing burn.
If one of these scenarios occurs, an investigation will not be required provided there was no serious injury or fatality, no damage to unrelated property and no debris outside designated hazard areas."