A missing lock ring. That was the finding. On September 4, 2022, a de Havilland Canada DHC-3 Turbine Otter floatplane carrying nine passengers and one pilot departed Friday Harbor in the San Juan Islands, bound for Renton Municipal Airport on the southern edge of Seattle. Twenty-one minutes later, the aircraft nosedived into Mutiny Bay off the southwest shore of Whidbey Island at high speed. Everyone on board died. The cause, investigators would eventually determine, was a small metal ring that was not where it was supposed to be.
The flight departed at 2:50 PM Pacific Daylight Time, a routine hop through the island-studded waters of Puget Sound. The DHC-3 Otter is a workhorse of Pacific Northwest float flying, a single-engine turboprop designed to haul passengers and cargo in and out of places that lack conventional runways. Pilot Jason Winters had decades of experience at the controls. The aircraft, registered N725TH, was operated by West Isle Air doing business as Friday Harbor Seaplanes, a service owned by Northwest Seaplanes. At 3:11 PM, witnesses on shore saw the plane plunge nose-first into the water at high speed. The impact, they reported, disintegrated the aircraft. The smell of aviation fuel spread across the bay.
Mutiny Bay, despite its name, is typically placid, a shallow indentation on Whidbey Island's southwestern coast where the water deepens quickly offshore. The wreckage sank to 190 feet. The National Transportation Safety Board opened an investigation and enlisted NOAA vessels, the University of Washington Applied Physics Laboratory's side-scan sonar, and eventually the U.S. Navy with remotely operated vehicles and a recovery barge. The aircraft carried no flight data recorder and no cockpit voice recorder, nor was it required to. Recovery efforts on September 26 brought up most of the wreckage and the remains of several victims, including pilot Winters and members of actress Megan Hilty's family: her pregnant sister, brother-in-law, and young nephew.
On October 24, 2022, the NTSB released a critical update. The horizontal stabilizer actuator, the mechanism that controls the aircraft's pitch trim, had separated into two pieces at a threaded assembly fitting. The actuator's lock ring, a small but essential component that prevents the assembly from unthreading during flight, was missing from the wreckage. Without it, vibration could gradually unscrew the clamp nut, allowing the horizontal stabilizer to move freely. Within a day, Viking Air, which manufactures the DHC-3, issued a service letter requiring all Otter operators to inspect their actuators. The NTSB went further, recommending the immediate grounding of all DHC-3 seaplanes pending inspection and urging both the FAA and Transport Canada to act.
The NTSB's final report, released September 29, 2023, confirmed the probable cause. The clamp nut had unthreaded from the horizontal stabilizer trim actuator barrel because the lock ring was missing. As the nut worked loose, the horizontal stabilizer shifted to an extreme trailing-edge-down position, pitching the nose violently downward. The aircraft became uncontrollable. The plane had passed a 100-hour inspection before the flight, but the inspection protocols had not caught the absent ring. The crash forced a reckoning across the floatplane industry, a community of operators and passengers who depend on aging but beloved aircraft types in some of the most scenic and remote corridors in North America. Mutiny Bay, once just a quiet stretch of Puget Sound water, now carries a heavier name.
Crash site located at approximately 47.99°N, 122.59°W in Mutiny Bay, off the southwest coast of Whidbey Island. The bay is visible between Whidbey Island and the Kitsap Peninsula. Exercise caution and respect in the area. Nearest airports: KORS (Orcas Island, 30 nm NW), KRNT (Renton Municipal, 35 nm SE), W10 (Whidbey Airpark, 8 nm N). The waters here are part of the busy Puget Sound floatplane corridor between the San Juan Islands and Seattle.