Airworthiness Directives; Airbus Canada Limited Partnership (Type Certificate Previously Held by C Series Aircraft Limited Partnership (CSALP); Bombardier, Inc.) Airplanes

The FAA proposes to adopt a new airworthiness directive (AD) for certain Airbus Canada Limited Partnership Model BD-500-1A11 airplanes. This proposed AD was prompted by an investigation of an in- service hydraulic fluid leakage event that indicated the potential use of an uncalibrated torque wrench when tightening the union fittings at the pressure and return interfaces of all three rudder hydraulic power control units (PCUs). This proposed AD would require properly torquing the rudder PCU hydraulic fittings and applying the torque seal on the rudder PCU hydraulic fittings, as specified in a Transport Canada AD, which is proposed for incorporation by reference (IBR). The FAA is proposing this AD to address the unsafe condition on these products.