Washington: The day after Ethiopia released a preliminary crash report on Ethiopian Airlines flight 302, four Boeing employees called a Federal Aviation Administration (FAA) whistleblower hotline that allows employees and the public to report aviation safety issues, the media reported on Saturday.
An informed source said on Friday that the hotline submissions involved current and former Boeing employees describing issues related to the angle of attack sensor -- a vane that measures the plane's angle in the air -- and the anti-stall system called MCAS, which is unique to the Boeing 737 MAX plane, CNN reported.
All of the 737 Max planes worldwide have been grounded after the two crashes that occurred within a span of five months that killed a total of 346 people.
The FAA told CNN on Friday that it received the four hotline submissions on April 5, and it may be opening up an entirely new investigative angle into what went wrong in the crashes of two Boeing 737 Max commercial airliners -- Lion Air flight 620 in October 2018 and Ethiopian Air flight 302 on March 10.
Among the complaints is a previously unreported issue involving damage to the wiring of the angle of attack sensor by a foreign object, according to the source.
Other reports by the whistleblowers involved concerns about the MCAS control cut-out switches, which disengage the MCAS software, according to the source.
A preliminary report by Ethiopian investigators found that a malfunctioning angle of attack sensor on Ethiopian Airlines flight 302 was sending incorrect data to the MCAS system. The MCAS, behaving as if it were in a stall, repeatedly forced the nose of the plane down as the pilots struggled for control, and ultimately the aircraft crashed.
The problems on board the Ethiopian Airlines jet have appeared to be similar to those encountered on the Lion Air flight.
Boeing is yet to respond on the whistleblower reports.
The airline's CEO will hold a news conference on April 29 following a shareholder meeting in Chicago.
A meeting of international civil aviation authorities is also taking place the same day in the Dallas area to discuss the issues surrounding the 737 MAX.