INITIAL LIFTOFF AND HOVER WERE NORMAL, HOWEVER, AS THE PILOT, WHO WAS FLYING FROM THE LEFT SEAT, WAS PREPARING TO TAKEOFF, HIS CYCLIC DISCONNECTED AND CAME OUT OF THE FLOOR MOUNT. THE PILOT YELLED TO THE RATED PASSENGER TO TAKE THE CYCLIC AND HE LOWERED COLLECTIVE WHILE ATTEMPTING TO MAINTAIN DIRECTIONAL CONTROL WITH THE PEDALS. THE AIRCRAFT SUBSEQUENTLY LANDED HARD IN A TAIL LOW ATTITUDE, SEVERING THE TAILBOOM. INVESTIGATION REVEALED THAT THE 'PIP' PIN WHICH NORMALLY SECURED THE CYCLIC TO THE CONTROL MOUNT WAS MISSING AND NOT FOUND. EXAMINATION OF THE COMPONENTS DID NOT REVEAL ANY EVIDENCE OF WORKING, ELONGATION, OR DAMAGE IN THE HOLES WHERE THE PIN WOULD HAVE NORMALLY BEEN INSTALLED. AUDIT OF THE MAINTENANCE RECORDS OF THE AIRCRAFT, WHICH HAD BEEN DELIVERED FROM THE MANUFACTURER 2 DAYS PRIOR TO THE ACCIDENT, REVEALED THAT THE DUAL CONTROLS HAD RECENTLY BEEN INSTALLED AND INSPECTED AT THE FACTORY.