4 Sep 2022: DEHAVILLAND DHC-3 — Friday Harbor Seaplanes

4 Sep 2022: DEHAVILLAND DHC-3 (N725TH) — Friday Harbor Seaplanes

10 fatalities • Freeland, WA, United States

Probable cause

The in-flight unthreading of the clamp nut from the horizontal stabilizer trim actuator barrel due to a missing lock ring, which resulted in the horizontal stabilizer moving to an extreme trailing-edge-down position rendering the airplane’s pitch uncontrollable.

— NTSB Determination

Accident narrative

HISTORY OF FLIGHTOn September 4, 2022, about 1509 Pacific daylight time, a float-equipped de Havilland DHC-3 (Otter), N725TH, was destroyed when it impacted the water in Mutiny Bay, near Freeland, Washington, and sank. The pilot and nine passengers were fatally injured. The airplane was owned by Northwest Seaplanes, Inc., and operated as a Title 14 Code of Federal Regulations (CFR) Part 135 scheduled passenger flight by West Isle Air dba Friday Harbor Seaplanes. The flight originated at Friday Harbor Seaplane Base (W33), Friday Harbor, Washington, with an intended destination of Will Rogers Wiley Post Memorial Seaplane Base (W36), Renton, Washington. Visual meteorological conditions prevailed at the time of the accident.

Contributing factors

  • Maintenance personnel
  • Manufacturer
  • Malfunction
  • Maintenance personnel
  • Maintenance provider
  • Maintenance provider

Conditions

Weather
VMC, wind 310/10kt, vis 10sm

Related events

Same aircraft

  • 11 Apr 2026 — DEHAVILLAND DHC-3 NO SERIES (Key West Seaplane Adventures)
  • 28 Jul 2022 — DEHAVILLAND DHC-3 (Rust's Flying Service, INC)
  • 24 May 2022 — DEHAVILLAND DHC-3 (Yakutat Coastal Airlines)
  • 21 Feb 2022 — DEHAVILLAND DHC-3 (BALD MOUNTAIN AIR SERVICE INC)
  • 21 Aug 2021 — DEHAVILLAND DHC-3 (Brooks Range Aviation)

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