Date: 201208
Local time of day: 1201-1800
Location: ZZZ.Airport, US
Flight conditions: VMC
Light: Daylight
Aircraft: Cessna Stationair/Turbo Stationair 6
Operator: Government
Operating under: Part 91
Flight plan: IFR
Mission: Passenger
Flight phase: Takeoff / Launch
ATC / advisory: Tower ZZZ
Aircraft component: Exterior Pax/Crew Door
Component problem: Improperly Operated
Reporter organization: Government
Reporter function: Pilot Flying; Instructor
Reporter qualification: Flight Crew Multiengine; Flight Crew Flight Instructor; Flight Crew Instrument; Flight Crew Air Transport Pilot (ATP)
Human factors: Workload; Distraction; Confusion; Training / Qualification
Anomaly: Aircraft Equipment Problem Critical; Deviation / Discrepancy - Procedural Published Material / Policy
Detector: Person Flight Crew
When detected: Other Takeoff Roll
Result: Flight Crew Rejected Takeoff; General Maintenance Action
Contributing factors: Environment - Non Weather Related; Human Factors; Procedure
Primary problem: Human Factors

Narrative: I; along with 3 of my pilot co-workers; was returning from dropping another aircraft off at maintenance. We were all qualified in the aircraft category and class we were flying. I was the flight instructor and PIC and sat in the front right seat. The Mechanic/pilot was in the front left seat. He was qualified and current to fly the aircraft. The other two pilots were in the two seats in the next row. I did part of the preflight; confirming the other pilot did the rest. I got in the front right seat first. The two pilots in the back got in next and the pilot/Mechanic got in last. In this aircraft; the door for the front row is on the left side and door for the back rows is on the right side. The pilot/Mechanic in the front left seat shut the front door. The pilot in the back right seat shut the back door from the inside. The back door is operated by closing and latching the aft door; and closing the forward door after that (like a French door). He started the aircraft; did the run-ups and; using the checklist; did the cockpit preflight items; confirming the door was shut. He called for clearance and taxi and we taxied to the runway. After receiving clearance for takeoff; he began his takeoff roll. As we were about to rotate I heard a loud BOOM and called for the takeoff to be aborted. As I looked back; I noticed the rear right door had blown open. We announced that we were aborting and taxied back to the ramp. Upon inspection on the ramp; a small metal piece of the door was missing. We called the Tower and informed them. They did a FOD check on the runway; found the piece and returned it to us. Upon discussion and inspection of the door we concluded the pilot in the back right seat had not secured it. Upon rotation the plane flexed slightly; part of the door caught the relative wind and it blew open. Several things led to this occurrence and can be done to prevent it in the future. First; the door should have been secured from the outside by the pilot in command. Secondly; one pilot; the pilot in command should do the entire preflight; and not split the duties with the other pilots. Regardless of the qualifications of the other pilots; the PIC is ultimately responsible for ensuring the aircraft is fit for flight. By splitting the duties; or assuming the other pilot/passengers know what to do; things are overlooked. This situation has been de-briefed and company procedures.




Synopsis: Two C-206 pilots; the Instructor and the pilot flying; split the preflight duties because both were current and qualified. Two additional qualified pilots were in the rear seats but somehow the right aft door was not closed completely and came open during takeoff damaging the door.