Boeing 737 Max 8 flow by South West Airlines rocked side to side while in air, a potentially dangerous movement known as a Dutch Roll.

US regulators are investigating Boeing planes after issues have emerged at a time when the safety record of is under intense scrutiny, that the Federal Aviation Administration (FAA) as part of their new two inquiries. The agency is also involved after Boeing reported learning of potentially falsified documents used to certify titanium in its planes. Boeing referred questions about the Southwest Flight to the airline, which said it was co-operating with the investigation. Boeing said it sourced titanium metal  separately from its supplier and it believed a small number of parts had been affected, and the titanium issue was “industry –wide” involving shipments from a limited set of suppliers. It said tests performed so far indicate that the correct alloy was used, despite the false documentation. The company also said “ To ensure compliance, we are removing any affected parts on airplanes prior to delivery. Our analysis shows the in-service fleet can continue to fly safely”. According to The New York Times, which first reported the issue, said a supplier to Spirit AeroSystems, which makes parts for Boeing and European plane-maker Airbus, started looking into the issue after noticing holes from corrosion.

Spirit has alerted two manufacturers said more than 1, 000 tests had been completed on the suspect parts which had been removed from production.