Airworthiness Directives; Raytheon Model Hawker 800 and 1000 Airplanes and Model DH.125, HS.125, BH.125, and BAe.125 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Raytheon Model Hawker 800 and 1000 airplanes and Model DH.125, HS.125, BH.125, and BAe.125 series airplanes, that requires replacement of cadmium plated fittings and cone caps in the oxygen system plumbing with improved fittings and cone caps, a detailed visual inspection of the oxygen system plumbing in the area of the replaced parts, and corrective actions, if necessary. This amendment is prompted by reports indicating that a field survey of the affected parts revealed that a reaction process was occurring, which resulted in cadmium flaking. The actions specified by this AD are intended to prevent flaking of cadmium from certain oxygen system plumbing fittings and cone caps from blocking the valves and impairing the function of the oxygen system, which could deprive the crew and passengers of necessary oxygen during an emergency that requires oxygen.