DEHAVILLAND DHC-3
Freeland, WA — September 4, 2022
Event Information
| Date | September 4, 2022 |
| Event Type | ACC |
| NTSB Number | DCA22MA193 |
| Event ID | 20220905105855 |
| Location | Freeland, WA |
| Country | USA |
| Coordinates | 47.99032, -122.58502 |
| Highest Injury | FATL |
Aircraft
| Make | DEHAVILLAND |
| Model | DHC-3 |
| Category | AIR |
| FAR Part | 135 |
| Aircraft Damage | DEST |
Conditions
| Light Condition | DAYL |
| Weather | VMC |
Injuries
| Fatal | 10 |
| Serious | 0 |
| Minor | 0 |
| None | 0 |
| Total Injured | 10 |
Event Location
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.
Full 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.
About This NTSB Record
This aviation event was investigated by the National Transportation Safety Board (NTSB). NTSB investigates all U.S. civil aviation accidents to determine probable cause and issue safety recommendations to prevent future accidents.