Incident Overview
On December 31, 2008, at approximately 1040 Alaska Standard time, a Cessna 207A airplane, registration N39AK, sustained substantial damage when its aft cargo door opened in flight. The event occurred about 7 miles north-northeast of Hoonah, Alaska. The airplane was operating as a visual flight rules (VFR) commuter flight under 14 CFR Part 135, designated as Flight 15, by Wings of Alaska, based in 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 had originated at Juneau Airport at about 1029 and was en route to Hoonah.
Sequence of Events
According to a Federal Aviation Administration (FAA) inspector from the Juneau Flight Standards District Office (FSDO), who spoke with the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on January 5, 2009, the airplane was in cruise flight at 3,000 feet mean sea level over the Sisters Island VOR when the aft cargo door suddenly opened. The door, hinged to open rearward, struck the right side of the fuselage, producing structural damage to both the fuselage and the door. The flight continued to Hoonah and landed without incident. No cargo or mail was lost during the event.
Cargo Door Operation
The Cessna 207A information manual, Section 7, describes the cargo door operation. 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 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; 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 rotates the inside handle toward the locked position. The handle can then be locked via key. The manual notes that "Both doors must be securely closed and the forward door locked prior to flight..."
Post-Incident Inspection
During a telephone conversation with the NTSB IIC on January 5, 2009, the director of maintenance for the operator reported that he inspected the airplane in Hoonah on December 31. He stated that he did not detect any malfunction of the cargo door latch mechanism.