These GE guys really are a bunch of weasels. The situation is clear - if you stall an unmodified engine at 41,000 feet you have a pretty good chance of locking it irretrievably. If you make the modification you don't. But then they were as bad when the CF34 fan blades started disintegrating a couple of years ago. That time, despite usual GE lobbying, the safety board hit them with:
"...the National Transportation Safety Board recommends that the Federal
Aviation Administration:
Require GE Aviation to define a reasonable maximum cycle limit below
4,717 cycles since new for Teleflex-manufactured CF34-1/-3 fan blades,
considering the two failures and available data, and require that the blades be
removed from service before that limit is exceeded. (A-08-04)
Require GE Aviation to include dwell time fatigue testing in the CF34-1/-3 fan
blade manufacturing process requirements to verify that any modified
manufacturing process adequately reduces the possibility of the presence of
aligned alpha colonies in the finished part. (A-08-05)
Require GE Aviation to make modifications to the CF34-1/-3 engine design and
ensure that an engine unbalance event will not cause the engine to catch fire.
(A-08-06)"
i.e. - Take out the dodgy blades, test new ones properly and make sure the fire extinguishers work. Should they really need safety directives to tell them that?
Which makes you wonder whether the GE lobbying that got them exempted from the full blade off test for the GEnX will come back to haunt them when they get their first uncontained fan failure...