Airworthiness Directives; The Boeing Company Airplanes

We are superseding two existing airworthiness directives (AD) that apply to certain The Boeing Company Model 737-100, -200, -200C, - 300, -400, and -500 series airplanes. Those ADs, for certain airplanes, currently require repetitive inspections of the flap track of the wing outboard flap, and corrective actions if necessary; and eventual rework of the flap track assembly and rear spar attachments. For certain airplanes, this new AD adds repetitive inspections, scheduled overhauls, correct alignment during installation, and repetitive maintenance of the flap track, and corrective actions if necessary. This new AD also adds airplanes to the applicability. This AD was prompted by reports that the work sequence and procedures used during installation of replacement tracks could cause loose or cracked tracks. We are issuing this AD to detect and correct cracking and damage in the flap track, which could cause loss of the outboard trailing edge flap and consequent reduced controllability of the airplane.