Airworthiness Directives; Short Brothers Model SD3-30 and SD3-60 Series Airplanes Equipped With Fire Fighting Enterprises (U.K.) Ltd. Fire Extinguishers

This amendment adopts a new airworthiness directive (AD), applicable to all Shorts Model SD3-30 and SD3-60 series airplanes equipped with certain fire extinguishers, that requires replacement of the covers for fire extinguisher adapter assemblies that are installed on certain bulkheads with new covers that swivel to lock the extinguishers in place; and replacement of nozzles and triggers on these fire extinguishers with better fitting nozzles and stronger triggers. It also requires the installation of new fire extinguisher point placards and a revision of the Airplane Flight Manual to instruct the flight crew in the use of the new covers for these adapter assemblies. This amendment is prompted by reports that these fire extinguishers are not discharging properly because they do not fit correctly with the adapter, and that triggers on these extinguishers are failing. The actions specified by this AD are intended to ensure that, in the event of fire in the baggage bay, extinguishing agent is properly distributed within this area, and portable extinguishers operate properly; and to prevent injury to crew and passengers when a portable extinguisher is discharged.