GE, me and the old lady next door all agree that a blade off test is not relevant in the containment issue. RR et al all end up with large lumps of metal lunging around the fan case several times trying desparately to get out after a failure. The clever bods at GE on the other hand have amply demonstrated that an impact causes the blade, in the bat of an eyelid, to revert to dust - hence kinetic energy gone in a flash ! . . That's what we reckon anyhow !