Summary
This document revises an earlier proposed airworthiness directive (AD), applicable to certain McDonnell Douglas Model MD-90-30 airplanes, that would have required repetitive inspections and functional tests of the static port heater assemblies, an inspection of the static port heaters and insulators, and corrective actions if necessary. This new action revises the proposed AD by adding repetitive inspections of the static port heaters and insulators and revising the functional test of the static port heater assemblies. The actions specified by this new proposed AD are intended to prevent an electrical short of the static port heater from sparking and igniting the insulation blanket adjacent to the static port heater, which could result in smoke and/or fire in the cabin area. This action is intended to address the identified unsafe condition.