Airworthiness Directives; Boeing Model 737-100, -200, -200C, -300, -400, and -500 Series Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to all Boeing Model 737-100, -200, -200C, -300, -400, and -500 series airplanes, that currently requires repetitive inspections to find cracks, fractures, or corrosion of each carriage spindle of the left and right outboard mid-flaps; and corrective action, if necessary. That AD also provides for an optional action of overhaul or replacement of the carriage spindles. This amendment requires repetitive gap checks of the inboard and outboard carriage of the outboard mid-flaps to detect fractured carriage spindles; and corrective actions, if necessary. This amendment also reduces the interval for the existing inspections and revises the overhaul procedures. The actions specified in this AD are intended to detect and correct cracked, corroded, or fractured carriage spindles and to prevent severe flap asymmetry, which could result in reduced control or loss of controllability of the airplane. This action is intended to address the identified unsafe condition.