| Date: | Sunday 4 September 2022 |
| Time: | 15:09 |
| Type: |  de Havilland Canada DHC-3T Turbine Otter |
| Owner/operator: | Friday Harbor Seaplane Tours |
| Registration: | N725TH |
| MSN: | 466 |
| Year of manufacture: | 1967 |
| Total airframe hrs: | 24430 hours |
| Engine model: | General Electric H80-200 |
| Fatalities: | Fatalities: 10 / Occupants: 10 |
| Aircraft damage: | Destroyed, written off |
| Category: | Accident |
| Location: | 3 km SW off Freeland, WA -
 United States of America
|
| Phase: | En route |
| Nature: | Passenger - Non-Scheduled/charter/Air Taxi |
| Departure airport: | Friday Harbor SPB, WA (FBS) |
| Renton Airport, WA (RNT/KRNT) | |
| Investigating agency: | NTSB |
| Confidence Rating: |  Accident investigation report completed and information captured |
A float-equipped de Havilland Canada DHC-3T Turbine Otter, N725TH, was destroyed when it impacted the water in Mutiny Bay, Washington. All ten occupants were killed in the accident.
The accident flight departed from Friday Harbor Seaplane Base, Washington, about 14:50 with a destination of Renton-Will Rogers Wiley Post Memorial Seaplane Base, Washington. Track data indicated the airplane flew at an en route altitude of 650 to 975 ft above mean sea level (msl), and the groundspeed was between 115 and 125 knots.
At 15:08:43, the airplane pitched up about 8° and then abruptly pitched down about 58°. The data ended at 15:08:51, when the airplane’s altitude was 600 ft msl and the estimated descent rate was more than 9,500 ft per minute.
Witnesses near the accident site reported that the airplane was in level flight before it entered a slight climb, then pitched down in a near-vertical descent. The airplane continued in a nose low, spiraling, near-vertical descent until it impacted water in Mutiny Bay.
The wreckage was located a week later, at a depth of 190 feet.
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.
Accident investigation:
 |
|
Sources:
AP
Photo
NTSB
Location
Revision history:
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