On January 24, 2018, about 1220 Alaska standard time, a tailwheel equipped DeHavilland DHC-2 airplane, N1544, sustained substantial damage following a loss of directional control while landing on an unimproved airstrip, near Kazakof Bay on Afognak Island, Alaska. The airplane was registered to and operated by Andrew Airways Incorporated as a 14 Code of Federal Regulations (CFR) Part 135 on-demand visual flight rules flight when the accident occurred. The commercial pilot sustained no injuries. Visual meteorological conditions prevailed and company flight following procedures were in effect. The flight departed Kodiak Airport (PADQ), Kodiak, Alaska about 1200 for the approximately 23 nautical mile flight to Kazakof Bay. According to the pilot, after overflying the unimproved airstrip, he landed to the west into an estimated 7 knot wind. The touchdown was normal, however when he applied the brakes during the ground roll, the airplane "veered hard to the right." He then added power in an attempt to gain control of the airplane. Subsequently, the airplane exited the unimproved airstrip to the right, traveled through alder bushes and small spruce trees, and came to rest against a dirt embankment. The right wing came to rest against the terrain and the right main landing gear separated from the gear box, resulting in substantial damage. The pilot stated that prior to the accident flight, the brake system had been flushed and bled due to two brake failures earlier in the day. The owner stated that the pilot had reported a "soft brake" on the left side on the previous flight. When the airplane was inspected by maintenance personnel, the brake system was bled and water was observed within the purged fluid. The owner further stated that during the summer, the brake cylinders were left in place while the airplane was on floats and suspected this may have been how the water entered the brake system. Prior to the airplane being operated on wheels, the hydraulic fluid was flushed from the system to ensure any water was removed. During the removal of the landing gear components for recovery of the airplane, the brake system was compromised, and no fluid was retained for testing for possible contamination. The closest official weather observation station 22 miles away is PADQ. At 1153, a METAR was reporting, in part, wind 280° at 16 knots, gusting 32 knots; visibility 10 statute miles; clouds and ceiling clear; temperature 21° F; dew point 5° F; altimeter 29.76 inches of Mercury.