Airworthiness Directives; MHI RJ Aviation ULC (Type Certificate Previously Held by Bombardier, Inc.) Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain MHI RJ Aviation ULC Model CL-600-2D15 (Regional Jet Series 705) and CL-600-2D24 (Regional Jet Series 900) airplanes. This AD was prompted by a report that torque wrenches used during production installation of bulkhead fittings on the oxygen lines of the flightcrew oxygen mask stowage boxes and adapter fitting on the oxygen pressure gauge were out of calibration, which resulted in a higher torque level setting than required. This AD requires replacement of the affected oxygen line fittings, as specified in a Transport Canada AD, which is incorporated by reference. The FAA is issuing this AD to address the unsafe condition on these products.