The pilot was departing on a post-maintenance flight check in a float-equipped deHavilland DHC-2 from a short water lane at a remote, unimproved seaplane base in Dilllingham, Alaska.
While taxiing for departure, he left the wing flaps in the “up” position to aid in turning the airplane on the water.
After aligning the airplane for the takeoff run, he applied full power, and the airplane accelerated onto the step. While attempting to rotate, he realized that he had forgotten to reset the wing flaps to the “takeoff” position.
He attempted to reset the manually operated, hydraulically actuated wing flaps, but the incorrect flap setting led to a longer-than-normal takeoff run, and the airplane hit the water lane’s far bank, which resulted in substantial damage to the left wing and left-wing strut.
The pilot reported that there were no preaccident mechanical anomalies with the airplane that would have precluded normal operation.
Probable cause: The pilot’s failure to set the wing flaps to the “takeoff” position, which resulted in a longer-than-normal takeoff run and collision with terrain.
NTSB Identification: ANC17CA038
This July 2017 accident report is provided by the National Transportation Safety Board. Published as an educational tool, it is intended to help pilots learn from the misfortunes of others.