“We’re concerned that another plane could crash as a result of something similar,” NTSB Chair Jennifer Homendy said at the time.
In an investigative update, the NTSB identified a lock missing from the actuator of the horizontal tail — also known as a stabilizer — which controls the pitch of the plane.
After crews recovered about 85% of the plane wreckage in September, investigators found the upper portion of the actuator was attached to the horizontal stabilizer, while the lower part was “attached to its mount in the fuselage” but disconnected.
While the NTSB has not officially said the actuator separation caused the crash, Homendy said the failure of the actuator could have caused the plane to plummet. Additional crashes could happen if the lock pin is missing or improperly installed.
An FAA spokesperson told The Seattle Times on Wednesday that the directive was issued after the manufacturer, Viking Air Limited, issued a service bulletin.
A problem with pitch control would be consistent with the “nose dive” reported by people who saw the plane hit Puget Sound.
Witnesses helped officials identify the crash site, search for survivors and locate the remains of one passenger.
It took the NTSB and U.S. Navy crews more than a week and several types of sonar to find what remained of the plane because of the depth and current of the channel where the aircraft hit. Remains of seven of the 10 people aboard have been located.