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

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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 in the horizontal stabilizer of the DHC-3 Otter.
The actuator separated due to an unthreaded clamp nut, which a lock ring is designed to prevent, potentially leading to a loss of pitch control.
Three of the five holes for the lock ring were damaged, potentially hindering proper engagement, and the NTSB has not determined if the lock ring was installed before the crash.
The NTSB is collaborating with Canadian authorities to issue a Service Letter advising DHC-3 operators worldwide to inspect the actuator for proper lock ring engagement.

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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.