causing deep damage to aft bh and rudder/elevator system
I don't think this will be covered by the tech log. Even a really big heater blanket just won't do. Heaven forbid trying to get a vacuum bag to seal!
I am aware that the FAA and EASA are struggling to establish size limits for composite repairs, but I suggest that by the above description, this damage would exceed even their wildest ideas.
So it looks as if carbon composites will not be used for the repair.
Not quite true, but the material type may be of less concern than the manner of joining the repair to the structure. Fasteners in composites in areas where they were not designed into the structure can be quite tricky because of the low bearing strength of composites in the structure. Adhesive bonding is far more efficient but the size of the bond may be prohibitive to achieve. I am sure there are a number of customers who are watching eagerly to see how/if Boeing undertake a repair of this size in composite structure.
I am also concerned about any evidence of release of carbon fibres due to combustion. Hopefully only resin was consumed and no fibres were released. If not, then the smallest particles of carbon will cause havoc with not only the aircraft electronics but those of any surrounding electrical or electronic equipment in adjacent aircraft or GSE. This would be an ideal time to determine just what the risk of fire in a composite aircraft really is.