American aircraft manufacturer Boeing defended its criticized safety methods on its production lines on Monday. The company said it was “confident in the safety and durability of the 787 and 777” during a briefing with two senior engineers.

They disputed accusations that some 1,400 Boeing planes had significant security flaws. A defense which comes two days before a delicate hearing in Congress on the assertions of a launch engineer alert concerning in particular the Dreamliner 787. The hearing comes as regulators and politicians step up scrutiny of the plane maker following a near-disastrous Jan. 5 flight on Alaska Airlines. A 737 MAX then lost a poorly sealed door in mid-flight, causing an emergency landing. These are now three of the four commercial aircraft models currently manufactured by the American group which are officially targeted by an investigation. The American civil aviation regulator, which has closely monitored Boeing's favorite 737 since January, is also investigating the787 Dreamliner and the 777, the structural integrity of which has been called into question by this whistleblower.