Airworthiness Directives; Boeing Model 757-200, -200CB, and -200PF Series Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to certain Boeing Model 757 series airplanes, that currently requires repetitive inspections for excessive wear of the internal and external splines of the torque tube couplings of the trailing edge flaps, and replacement of the couplings, if necessary. That AD also provides an optional modification that, if installed, constitutes terminating action for the inspection requirements. This amendment expands the applicability of the existing AD and requires new inspections of the torque tube assemblies and certain gearbox assemblies and universal joints in the drive system for the inboard trailing edge flaps, and follow-on actions if necessary. For certain airplanes, this amendment also adds a new optional modification, which, if installed, terminates certain inspections. The actions specified by this AD are intended to prevent separations in the drive system for the inboard trailing edge flaps, which could cause a flap skew condition that could result in damage to the flaps or fuselage, and consequent reduced controllability of the airplane.