AD FAA-2013-0542

We are superseding Airworthiness Directive (AD) 2010-15-08 for all The Boeing Company Model 737-100, -200, -200C, -300, -400, and -500 series airplanes. AD 2010-15-08 required repetitive inspections for discrepancies of each carriage spindle of the outboard mid-flaps; repetitive gap checks of the inboard and outboard carriages of the outboard mid-flaps to detect fractured carriage spindles; measuring to ensure that any new or serviceable carriage spindle meets minimum allowable diameter measurements taken at three locations; repetitive inspections, measurements, and overhaul of the carriage spindles; replacement of any carriage spindle when it has reached its maximum life limit; and corrective actions if necessary. This new AD requires reducing the life limit of the carriages, reducing the repetitive interval for certain inspections and gap checks for certain carriages. This new AD also adds an option, for certain replacements, of doing an inspection, and related investigative and corrective actions if necessary. This AD was prompted by a report of failure of both flap carriages. We are issuing this AD to detect and correct cracked, corroded, or fractured carriage spindles, which could lead to severe flap asymmetry, and could result in reduced control or loss of controllability of the airplane.