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Graphic toont hoe piloten de software van de Boeing 737 MAX MCAS kunnen omzeilen.


Aanpassing software Boeing 737 MAX

March 13, 2019 - Boeing voegt redundantie en andere limieten toe aan de fly-by-wire-software van de 737 MAX, zodat hij minder snel een duik zal initiëren om
overtrekken te voorkomen, wanneer het gevaar daarop niet bestaat.

The crashes of two Boeing 737 Max jetliners over the past five months in Ethiopia and Indonesia, killing almost 350 people in all, have resulted in the grounding of more than 300 Boeing 737 MAX 8 and MAX 9 passenger jets around the world.

Following the Lion Air flight 610 crash in October, Boeing issued a bulletin warning MAX operators that the plane’s angle of attack (AOA) sensor can produce erroneous indications causing the jet to enter an aggressive dive.

False data would trigger the anti-stall system -- known as the Maneuvering Characteristics Augmentation System, or MCAS. The pilot’s first warning would be a “stick shaker” vibrating the yoke and loud aural commands: “Airspeed low! Airspeed low!”

Bulletin TBC-19 advises that in the event of erroneous AOA data the pilot should use the stabiliser trim switches on the outside of the yoke to temporary reverse the MCAS nose down movement.

The next step, according to the Boeing bulletin, would be to reach across to the central console and flip a pair of stabiliser trim cutout switches to off. These switches would disable electric control of the jackscrew motor that moves the stabilisers up and down.

The final step is to spin two trim wheels, found on either side of the central console, to manually control the stabilisers for the remainder of the flight.

PUBLISHED: 18/03/2019; STORY: Graphic News; PICTURES: The Boeing Company