In common with many others, I've read every post made on this venerable and informative thread and it’s good to see their quality and thought-provoking nature being maintained. (Until this one…….)
The issue of bypassing the FOHE has been covered in detail already. If memory serves, one contributor, presumably with tongue firmly in cheek, even claimed a pat pending on his particular solution.
But I'm with you sky9, how can we actually deal with the rollback problem is the key. As we don't know what the problem actually is, that makes things really tough.
Presumably the question is how much ice in the injectors can be handled before blockage and presumably flameout never mind rollback, occurs?
I have the greatest of respect for the quality of the engineers working for RR and I'm quite sure that this will already have been looked at exhaustively by RR. I'm also naïve enough to take on trust that if it was just a matter of putting in a simple bypass system, RR would've done it long ago.
CW