I have to agree with Arm Out The Window (and others) on this one. With more than 3000 hours in the AS 350 series I have never experienced jack stall except when demonstrating it to students. Even then it usually took a couple of attempts at extreme manoeuvring to achieve incipient jack stall. As I recall the aircraft basically recovers immediately by itself as the pilot "automatically" (you have to be there) relaxes pressure on the cyclic. Any aircraft will experience problems if pushed far enough, as others have pointed out. This is not a design flaw. By the way Lu, the 350 hydraulic system does have accumulators.