With reference to the two 13 Sqdn. PR9s that crashed in Malta. I was on 39 Sqdn. in 1970 and we were well aware that something 'odd' had happened and had been checking flying controls and autopilot systems on the whole fleet. The finger was pointed at the hydraulic powered flying control system on the ailerons and the tailplane trim actuator. The powered ailerons were only fitted to the PR9 to my knowledge and although nothing could be found, it was thought that a fault in this system could have caused the accidents as the aircraft were reported to have rolled and crashed inverted. The autopilot system was ruled out as it was unlikely to have been selected when the accidents occured. The aircrew were warned to be cautious if the aircraft 'twitched' in the roll axis and I can remember at least one aircraft returning, having declared an emergency, with the navigators escape hatch missing! In the PR9, the navigator was in a closed compartment in the nose and although he could eject through a frangible hatch it was considered preferable to jettison it first. That crew reported that they had experienced an aileron twitch and gave serious thought to ejecting. We never found anything conclusive and eventually everything went quiet and flying returned to normal, but it took about a year for the aircrew to settle down. Quite understandably they would, like the rest of us,like to have known what the cause of the accidents was. If the cause was ever identified, I never got to hear about it.
CC