NTSB Probe Into Downed DHC-3 Seaplane Focuses on Tail

In a new report, the National Transportation Safety Board said it is focusing on a broken part as a potential cause of the September Otter accident that killed 10 people.

Meg Godlewski

Monday, October 24, 2022 at 06:22 PM ET

Verified

The National Transportation Safety Board (NTSB) released a report Monday that says a broken actuator on the horizontal stabilizer could potentially be the cause of the aircraft's fatal plunge into the Puget Sound. [Image courtesy: NTSB]

Key Takeaways:

The NTSB investigation into the fatal seaplane crash north of Seattle is focusing on a broken actuator on the horizontal stabilizer, a critical component for the aircraft's pitch control.
The actuator separated due to an unthreading clamp nut, a failure mechanism typically prevented by a lock ring that was either missing or improperly engaged/damaged.
This likely led to a free-floating horizontal stabilizer and loss of aircraft control, prompting the NTSB to work with manufacturers on new inspection instructions for DHC-3 operators globally.

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The investigation into the crash of a seaplane north of Seattle last month that killed 10 people is focusing on the tail of the de Havilland Canada DHC-3 Otter turboprop. The National Transportation Safety Board (NTSB) released a report Monday that says a broken actuator on the horizontal stabilizer could potentially be the cause of the aircraft’s fatal plunge into the Puget Sound.

The actuator is part of the aircraft’s pitch control. If the actuator is compromised, the aircraft can enter an uncommanded climb or descent from which the pilot cannot recover.