My understanding is that in the 1990's, RR patented it's Fan Blade design. Subsequently PW tried and failed to have the patent disallowed. Earlier this year, RR commenced legal proceedings against PW for violation of patent because of the Fan Blade shapes on their PW1000G and GP7200 engines. Using the old adage that the best defence is attack, PW lodged a counter-suit against RR because their patent is "invalid and unenforceable" (ie even though they lost their attempt to have the RR patent disallowed, they refuse to accept the court's decision). The latest action by PW to try to make it illegal for Boeing to import Trent 1000's is really raising the stakes because of the critical nature of the B787 production. I suspect that there is a lot of politics going on behind the scenes.
Apologies for the thread drift.
ILS27Left, thanks for posting the details of the AD.