NEW YORK, March 27 — Boeing has flown test flights of its 737 MAX to evaluate a fix for the system targeted as a potential cause of two deadly plane crashes, two sources familiar with the matter said yesterday.
The aviation giant, which has been under fire and has seen its flagship narrow-body planes grounded since March 13, tested the system upgrade on Monday, two days after pilots from American and Southwest Airlines did simulation flights in Renton, Washington, the sources said.
Boeing needs authorisation from the Federal Aviation Administration before the MAX can return to service. But the company still has not submitted its proposed software patch to the FAA, a government source told AFP.
The aircraft was grounded following two deadly accidents involving Ethiopian Airlines earlier this month and Lion Air in October which together killed 346 people.
Engineers have been focusing on problems with the MCAS, a stall prevention system designed to point the nose of the 737 MAX 8 downward if it is in danger of stalling, or losing lift.
The system has been criticised since it can malfunction and make it difficult for pilots to control the aircraft. Both of the recent crashes occurred moments after takeoff.
The MCAS, or Manoeuvring Characteristics Augmentation System, was installed in the MAX because the engines are heavier than in the previous version of the 737.
Boeing remains under intense pressure following the two crashes, which will be the subject of a Senate hearing today. A company spokesperson declined to comment, but said the company is in regular contact with regulators.
Preliminary results in the investigation into October's Lion Air crash in Indonesia indicate a single “angle of attack” sensor, which feeds data to the MCAS, malfunctioned but continued transmitting data to the plane's flight systems, including the MCAS.
Among the changes to the system, the MCAS would automatically be disabled in cases where there is disagreement between two sensors, the sources told AFP.
Boeing also intends to make standard on planes a “disagree light,” to signal when the MCAS malfunctions. The feature currently is only available to airlines for an additional charge. — AFP