On December 31, 2008, about 1040 Alaska Standard time, a Cessna 207A airplane, N39AK, sustained substantial damage when the aft cargo door opened in flight, about 7 miles north-northeast of Hoonah, Alaska. The airplane was being operated as a visual flight rules (VFR) commuter flight under Title 14, CFR Part 135, when the accident occurred. The airplane was operated as Flight 15, by Wings of Alaska, Juneau, Alaska. The commercial certificated pilot, and the sole passenger, were not injured. Visual meteorological conditions prevailed, and VFR company flight following procedures were in effect. The flight originated at the Juneau Airport about 1029, and was en route to Hoonah. During a telephone conversation with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC), on January 5, 2009, a Federal Aviation Administration (FAA) inspector, Juneau Flight Standards District Office (FSDO), reported that the airplane was in cruise flight at 3,000 feet msl, over the Sisters Island VOR, when the aft cargo door suddenly opened. The door, which is hinged to open in a rearward direction, struck the right side of the fuselage, producing structural damage to the fuselage and door. The flight continued to Hoonah, and landed without incident. No cargo or mail was lost during the event. According to the Cessna 207A information manual, Section 7 states, in part, that the forward cargo door is opened by pivoting the door handle outward from its recessed position near the aft edge of the forward door, and then pulling outward on the handle. After the forward door is opened, the aft door may be opened by grasping the red handle on the forward edge of the door, and pulling downward to release its locking pawls. The cargo doors are locked from the inside by rotating the inside handle counterclockwise to the "Locked" position, and when locked, the door cannot be opened from the outside. The outside cargo door handle can be used to lock the forward door by pivoting the handle out of its recess, and moving the vertical tab of the connecting link outward from behind the handle to engage a detent at its forward end. Pushing the handle back into its recess will rotate the inside handle toward the locked position. The handle can then be locked via key. The information manual notes that, "Both doors must be securely closed and the forward door locked prior to flight..." During a telephone conversation with the NTSB IIC, on January 5, the director of maintenance for the operator reported that he inspected the airplane in Hoonah on December 31. He said he did not detect any malfunction of the cargo door latch mechanism.