The British Army has always known about this with our Gazelles. When carrying out any hard right turn, I would always reduce collective a little bit to reduce the load on the servos, and never had a problem.
Is it a design fault? Possibly, but the aircraft concerned are fairly light aircraft with generally light control forces. Therefore the pressure within the hydraulic system only needs to be fairly low in order to control the aircraft. Hence the ease with which this pressure can be overcome.
Larger, heavier aircraft have heavier control forces therefore require higher hydaulic pressures. The Lynx hydraulic system is at around 3000psi and doesn't have a jackstall problem, but you can't really put a 300psi system on a 350/355.
Of course, all of the above could be b****ks.
