Airworthiness Directives; de Havilland Model DHC-8-100 and -300 Series Airplanes

This amendment supersedes an existing airworthiness directive (AD), applicable to all de Havilland Model DHC-8-100 and -300 series airplanes, that currently requires an inspection to detect discrepancies and damage of the low fuel pressure switch adapter/ snubber (located on each engine fuel heater), and replacement, if necessary. That AD also requires an inspection to detect gaps or openings in each nacelle and engine-mounted firewall area, and in certain weather seals in the nacelles; and correction of discrepancies. This amendment requires certain new modifications to the nacelles that will minimize the passage of flammable fluid through the zones of the nacelle of each engine. The actions specified by this AD are intended to prevent the spread of fire through these zones in the event of an explosion during flight, and consequent structural damage to the airplane.