I think it is sensible to understand why the advice regarding the removal of dual controls is given. It is there so that the "lowest common denominator" category of passenger doesn't cause a control restriction or inadvertently cause control inputs.
Anyone of some intelligence, of sound mind and properly briefed would not do that. I would certainly leave the duals in for someone with ten hours rotary experience. We were sent solo after ten hours and were required to fly a full solo engine off landings sortie after 40 hours.
I once had the opposite problem. I turned up at a Gazelle on a rotors running crew change to teach EOLs. There were no dual controls fitted. I declined to take the aircraft, although there was no advice in the Flight Manual about that situation.
I would stress the briefing before flight! I did once have a scare after climbing out of a Whirlwind 10 after my sortie during a rotors running crew change. A fairly ancient Group Captain (he flew Mosquitos) was being taken for a familiarisation ride with my instructor. I remained at the aircraft "downstairs" ready to remove the wheel chock and was listening in on the intercom as the Groupie was being talked through his strapping in. I was leaning against the door sill on the right, with my back to the door and looking out of the disc.
My instructor said: "Now, just make sure you can reach all the controls..."
With that, the old Whirly gave a huge lurch to the right, tyres squealing and lifting me off my feet! I was propelled out and away from the aircraft. I kept running, I felt a jolt as my intercom pigtail jerked free but I went at least fifty yards or so before stopping to look behind!
"Groupie", being a fixed wing pilot, had done a "full and free movement" check, hadn't he!
