Summary
We propose to supersede an existing airworthiness directive (AD) that applies to all The Boeing Company Model 737-300, -400, and - 500 series airplanes. The existing AD currently requires repetitive inspections of the downstop assemblies on the main tracks of the No. 2, 3, 4, and No. 5 slats and the inboard track of the No. 1 and 6 slats to verify if any parts are missing, damaged, or in the wrong order; other specified actions; and related investigative and corrective actions if necessary. Since we issued that AD, the manufacturer has developed a modification, which, when installed, would terminate the repetitive inspections. This proposed AD would add an inspection of the slat can interior for foreign object debris (FOD), and removal of any FOD found; modification of the slat track hardware; an inspection for FOD and for damage to the interior surface of the slat cans; and related investigative and corrective actions, if necessary. We are proposing this AD to prevent loose or missing parts in the main slat track downstop assemblies, which could puncture the slat track housing and result in a fuel leak and consequent fire.