Just spit-balling here, but I wonder if this couldn't be a pneumatic over-pressure event.
The blown open service doors indicative of such an event.
It's clearly an inlet cowl separation, but what if it was from an internal event (over-pressure of the inlet TAI system) vs. an external event, that caused the cowl to fail in a localized area and then aerodynamic forces took over and tore the inlet apart and off the airframe. Separation in stages can easily cause the widespread damage we see.
Now, in my almost 30 years in the industry, I've never quite seen an inlet fail quite so bad.
Have to agree on most points with you, especially never seeing anything like this. But would the anti-ice nose cowl system be able to do that ? After entering the nose cowl the hot engine bleed air comes out of the piccolo tubes heating the LE of the nose cowl and then blows overboard through that vent at the bottom of the cowl. Did the vent become clogged ? How ? What is intriguing to me, is in the photo taken inflight, this one,
the big long patch of shiny metal on top of whats left of the nose cowl with the red sealant around it's perimeter. Do not remember seeing that in nose cowls. Looks to be a repair possibly, and the tear goes right along the edge of that area. and the tear along that area is pretty linear. The rest of the nose cowl that is left, the edge is jagged. A bad crack not caught ? Or was there a failure of the TAI system on #1 engine. The regulator on the TAI is supposed to keep pressure below 50psi. Did the TAI pressure switch illuminata before this event showing that TAI duct pressure was above 65psi ?
Pieces of that nose cowl as it came apart interrupting the airflow at that flight level could have stalled the compressor overpressurizing the bleeds, catching the VBVs and VSVs off guard, and bleed lines causing all those access panels to blow open. Will be interesting to see what the NTSB will find out in the investigation.