A single failure in a critical flight control component can lead to devastating consequences, as was tragically witnessed in the Mutiny Bay accident of September 4, 2022.
This incident, involving a float-equipped de Havilland DHC-3 airplane, claimed the lives of ten people and prompted urgent action from the National Transportation Safety Board (NTSB).
The Mutiny Bay Tragedy
On September 4 2022, a scheduled passenger flight between two seaplane bases in Washington took a horrifying turn when the DHC-3 airplane crashed into Mutiny Bay, near Freeland.
The aircraft sank in 200 feet of water, with no survivors. The flight was operated by West Isle Air, trading as Friday Harbor Seaplanes.
Eyewitness accounts and surveillance footage revealed a chilling sequence of events. The aircraft was in level flight before it inexplicably climbed slightly and then abruptly pitched down, plummeting at a rate of over 9,500 feet per minute into the water.
A Single Point of Failure
The NTSB, in collaboration with the Navy Supervisor of Salvage and Diving, managed to recover approximately 85 percent of the airplane from the ocean floor within 26 days of the crash.
Shockingly, investigators discovered that the actuator responsible for controlling the airplane’s pitch had disconnected from a critical control linkage.
This disconnection occurred before the crash and rendered the pilot unable to control the aircraft’s pitch.
In response to this key finding, the NTSB issued an urgent recommendation to the Federal Aviation Administration (FAA) and Transport Canada on October 26, 2022.
This recommendation called for an immediate inspection of the affected section of the flight control system in all DHC-3 airplanes.
The roots of this tragedy can be traced back to the aircraft’s design certification by the FAA in 1952. At that time, there was no requirement for a secondary locking device to secure flight control linkages.
It was only in 1996 that regulations were amended to mandate the inclusion of a secondary locking device in newly designed aircraft, but only if the loss of the primary device would compromise the aircraft’s safety.
Existing aircraft like the one involved in the Mutiny Bay accident were not retrofitted with this safety feature, relying solely on a single locking device.
The Need for Redundancy
NTSB Chair Jennifer Homendy stated, “The Mutiny Bay accident is an incredibly painful reminder that a single point of failure can lead to catastrophe in our skies.”
To ensure aviation safety, it is crucial to introduce redundancies throughout the aviation system. In light of the investigation’s findings, the NTSB made several recommendations.
The FAA and Transport Canada were urged to require operators of DHC-3 airplanes to install a secondary retention feature in the flight control system. Additionally, recommendations were made to Viking Air, the current type certificate holder.
Homendy emphasized, “We’re calling on the Federal Aviation Administration and their Canadian counterparts to eliminate the safety vulnerability identified by NTSB investigators, so this kind of tragedy never happens again.”