Airworthiness Directives; Puritan-Bennett Aero Systems Co., Cone and Seal Assemblies, Part Numbers 210543 and 210543-01

This amendment adopts a new airworthiness directive (AD) that applies to Puritan-Bennett Aero Systems Co. (Puritan-Bennett) cone and seal assemblies, part numbers 210543 and 210543-01, that were manufactured or repaired from August 1996 through July 1997. This AD applies to cone and seal assemblies regardless of whether or not they are attached to certain Puritan-Bennett sweep-on crew masks. The AD requires replacing any cone and seal assembly manufactured or repaired during the above time frame. This AD results from quality control tests that show that these cone and seal assemblies could have faulty ultrasonic welds. The actions specified by this AD are intended to prevent failure of the ultrasonic weld on the cone and seal assembly of the oxygen mask with consequent reduced oxygen flow through the mask, which could result in the crew not being able to obtain oxygen in an emergency situation.