20120523011149A

N207JB departed from opf at 15:45 for a planned 10 minute repositioning flight to its base at pmp. The flight was filed on an IFR flight plan. Two required crew members were on board. About five minutes after takeoff, while in cruise flight at an altitude of 3,000 feet MSL, and a cruise speed of about 230 KIAS the crew reported the main cabin door of the aircraft opened and departed the aircraft. The first officer (fo) was flying the aircraft in VMC conditions at the time. The captain, looking outside and seeing the ft. Lauderdale-Hollywood international airport (fll) beneath them, made the decision to divert there and assumed control of the aircraft. An uneventful landing followed, and the aircraft was directed to the Bombardier service center there. The door, and some of its components, landed on the westin diplomat hotel golf course, in a position of 25 59' 18" n, 080 07' 52" w, about 4 miles south of fll. The course was closed at the time, and there were no injuries or damage from the door reported. The door and some components which had landed nearby, were secured and delivered the following morning to the Bombardier facility at fll, where the aircraft had been secured pending an investigation. The manufacturer, upon learning of the event, contacted the NTSB and requested to be a party to the investigation. The iic was informed that NTSB involvement would be limited in nature. With the concurrence of the NTSB, the iic accepted the request and invited the manufacturer to serve as a technical advisor and party to the investigation. The following findings were significant:1. The hinge for the main passenger door was relatively intact, remained attached to the airframe, and operated smoothly. The door separated from the hinge along the rivet line which secured the door to the hinge. 2. The main passenger door upper half was found crushed from what is believed to be ground impact. 3. The lower forward and aft door roll latches were found in the unlocked position with no damage, and operated smoothly. 4. The upper forwarded and aft door roll latches were found in the unlocked position with no damage and operated smoothly. 5. No damage was observed to any of the fuselage mounted door locking structure, nor was any damage found on the forward and aft fuselage mounted door proximity sensors. 7. The control rod connecting the upper and lower roll latches was found crushed inside the air stair structure. Dents on the upper and lower surfaces of the control rod corresponded with internal door structure, and the location of the dents corresponded with the position the rod would be at if the door locking mechanism was in the unlocked position at the time the door impacted the ground.8. The fuselage beneath the door hinge was found to have a penetration aligned with the external door assist handle. 9. The external door "t" handle was found deployed, and in the unlocked position. 10. The fuselage immediately beneath the door had an impression similar to the "t" handle, and was at an angle aligned to the position that the "t" handle would be in when the door is unlocked. 11. The circuit breakers for the door warning system, located on the copilot's b outboard (#160) and d (#17) circuit breaker panels were open.