Modif Urgente Autopilot Boeing 777

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AVION
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Modif Urgente Autopilot Boeing 777

Message par AVION »

FAA release AD requiring new autopilot software for Boeing 777s


The FAA have released Airworthiness Directive AD_2010_06_09 requiring operators of Boeing 777-200, -200LR,-300,-300ER and Boeing 777F to install new software into all three flight director computers (left, center, right) within 90 days following April 1st in order to prevent inadvertent engagement of the autopilot on the ground during the takeoff run and in order to fix too low a climb gradient during takeoffs with one engine inoperative.

The FAA reported, that there had been 9 occurrences of rejected takeoffs above decision speed (V1) following inadvertent activation of the autopilot during the ground roll since 1995 (for example see: Incident: ANZ B772 at Tokyo on Jan 31st 2010, rejected takeoff and Incident: Air France B773 at Lagos on Jan 12th 2010, rejected takeoff). This activation of the autopilot results in higher than usual control forces necessary to rotate the aircraft (editorial note: leading crews to believe the airplane won't fly and reject takeoff during rotation of the aircraft). This scenario increases the risk of runway overruns.

At the same time Boeing company discovered during simulator tests, that the autoflight software maintains a climb gradient that is "less than optimal for obstacle clearance during a one-engine takeoff (performance-limited) situation". This scenario could lead to failure of clearing obstacles during a performance limited takeoff.

Both scenarios could lead to potentially catastrophic results, the FAA reasons to justify the immediate release of the Airworthiness Directive and require compliance within 90 days.
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