The FAA says the cause of the dive was apparently related to the movement of the captain’s seat, which caused the auto-pilot to disconnect.
The Federal Aviation Administration will require inspections of hundreds of Boeing 787 Dreamliners after a LATAM Airlines plane in March took a sudden midair plunge that injured at least 50 people.
The FAA said in a statement that the plane dived after a seat in the cockpit jolted forward and disconnected the autopilot system, causing a rapid descent. Since the incident, the FAA has received four additional reports of similar issues, the latest in June.
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The agency identified loose rocker switch caps on the backs of cockpit seats as the cause in three of the incidents. The two other cases remain under investigation.
As a result, the FAA issued an airworthiness directive, citing the "unsafe condition" of the seats, and required inspections of 158 U.S.-registered airplanes and 737 airplanes worldwide. The inspections must be completed within 30 days.
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A Boeing spokesperson said in response that company officials "fully support" the directive.
The announcement adds to the continuing regulatory and public scrutiny of Boeing, particularly concerning its 787 Dreamliner.
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In June, it discovered hundreds of incorrectly installed fasteners on some undelivered jets. In May, the FAA investigated whether Boeing had completed required inspections or falsified aircraft records. And the month before that, a whistleblower told NBC News that Boeing should halt Dreamliner production because of unresolved assembly flaws.
In response to the whistleblower's claims, Boeing said it was "fully confident" in the Dreamliner.
NBC News' Jay Blackman contributed.
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