I had the infamous Hyd Block where the shuttle valve only partially moved across to the secondary system. In the new hyd pack this was thought to be impossible due to the return line that had been incorporated. The Hyd Block was caused by a faulty micro switch and neither servo was stalled. Without going into too much detail, this resulted in all the pitch being thrown off the blades in a very short period of time and the subsequent extreme nose down attitude. Pulling on the cyclic in this situation makes little difference apart from the feeling of being part of a one man team. Fortunately for me, at just the right moment, the shuttle valve moved back to the primary side and control was restored at about 140kts. Cue some aeros that Red Bull would have been proud of and I ended up making contact with the ground in what wasn’t one of my finest moments. The full comedy saga then played out over the next two days. Suffice to say, the 105 wasn’t flown off the extremely remote place that it had ended up on....not under its own steam I should say.
The hyd pack was sent to Germany and put on a test rig and the same result was produced. As far as I am aware, 5x 105s have had a similar experience, 3 were German Army at low level (not a happy result) and the other ended up inverted at about 2000’.