The FAA issued an airworthiness directive (AD) for all The Boeing Company Model 787-8, 787-9, and 787-10 airplanes, that requires repetitive operational checks of the leading edge (LE) outboard (OB) slats and applicable on-condition actions.
This AD also requires revising the airplane flight manual (AFM) to prohibit flap retraction under icing conditions and revising the existing maintenance or inspection program, as applicable, to incorporate a new operation check.
The AD was raised after FAA received a report indicating that five LE OB slat geared rotary actuators (GRA) failed during taxi, causing the associated slats to be out of the commanded position with flight deck annunciation.
However, a subsequent review of the Boeing Model 787 high lift system identified a potential condition in which the LE OB slat system could be out of position without flight deck annunciation.
This condition, if not addressed, could result in insufficient lift, resulting in inability to maintain continued safe flight and landing.
The FAA issued this AD to address the unsafe condition on these products.
This AD is effective October 11, 2019.