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Sensor damaged by a foreign object on Ethiopian Airlines 737 MAX triggered fatal crash
The Ethiopian Airlines Boeing 737 MAX, which crashed in March and killed 157 people, suffered a damaged angle-of-attack sensor upon takeoff from a bird or foreign object, triggering erroneous data and the activation an anti-stall system -- called MCAS -- sending the pitch of the plane downward and ultimately crashing into the ground, two aviation sources familiar with the investigation told ABC News. As the jet was nose diving, the Boeing 737 MAX pilots did not try to electronically pull the… (www.yahoo.com) Más...Sort type: [Top] [Newest]
You people have to understand that the trim activates the horizontal stabilizer which is twice the size of the elevator controlled by the pilot so the pilot cannot overpower the trim when it is active. Now if the aircraft is in a high speed dive after the MCAS has run the trim to full nose down or close to it and is selected off by the pilot, the aerodynamic forces on the stabilizer (trim) are so strong that the pilot cannot override them in manual mode, this probably why they attempted to restart the electric trim in desperation to regain control in this short time event.
If this airplane cannot fly without the MCAS, it should not fly
Not just the aerodynamic forces, but the forces on that jackscrew..this is what former Boeing flight control engineer Peter Lemme speculated "“The forces on the tail could have been too great,” Lemme said. “They couldn’t turn the manual trim wheel.”
Good write up includes 2 European 737 pilots using a simulator to demonstrate Lemme's hypothesis https://www.seattletimes.com/business/boeing-aerospace/boeings-emergency-procedure-for-737-max-may-have-failed-on-ethiopian-flight/
Good write up includes 2 European 737 pilots using a simulator to demonstrate Lemme's hypothesis https://www.seattletimes.com/business/boeing-aerospace/boeings-emergency-procedure-for-737-max-may-have-failed-on-ethiopian-flight/
Exactly, which is why early recognition and immediate deactivation of the MCAS/runaway trim using the Trim CutOut Switches is imperative.
Easy enough to say, Highflyer, but we don't know how fast or long that MCAS system takes to turn the stab trim jackscrew...is it fast or slow retention?
Pilot_obet on instagram explains this in full detail in live action with the 747-8i on his page. Might I add what a fine work of engineering the 747-8i is, and what a shame no US passenger carrier uses this aircraft.