AD 2021-11-23 Also Requires, For Certain Airplanes, An Update Of The Hydraulic Monitoring System To Include Additional Redundancy

The FAA is adopting a new airworthiness directive (AD) for certain Airbus SAS Model A350-941 and -1041 airplanes.

This AD was prompted by a determination that new or more restrictive airworthiness limitations are necessary. This AD requires revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations, as specified in a European Union Aviation Safety Agency (EASA) AD, which is incorporated by reference. This AD also requires, for certain airplanes, an update of the hydraulic monitoring system to include additional redundancy. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective September 3, 2021.

Supplementary Information: The EASA, which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2020-0268, dated December 4, 2020 (EASA AD 2020-0268) (also referred to as the Mandatory Continuing Airworthiness Information, or the MCAI), to correct an unsafe condition for all Airbus SAS Model A350-941 and -1041 airplanes. EASA AD 2020-0268 refers to Airbus A350 Airworthiness Limitations Section (ALS), Part 5, “Fuel Airworthiness Limitations (FAL), ”Revision 04, dated May 29, 2020; and Airbus A350 ALS Part 5, “Fuel Airworthiness Limitations (FAL),” Variation 4.1, dated September 15, 2020. Airplanes with an original airworthiness certificate or original export certificate of airworthiness issued after September 15, 2020, must comply with the airworthiness limitations specified as part of the approved type design and referenced on the type certificate data sheet; this AD therefore does not include those airplanes in the applicability.

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain Airbus SAS Model A350-941 and -1041 airplanes. The NPRM published in the Federal Register on March 26, 2021 (86 FR 16117). The NPRM was prompted by a determination that new or more restrictive airworthiness limitations are necessary. The NPRM proposed to require revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations, as specified in EASA AD 2020-0268.

The NPRM also proposed to require, for certain airplanes, an update of the hydraulic monitoring system to include additional redundancy.

The FAA is issuing this AD to address the overheat failure mode of the hydraulic engine-driven pump (EDP), which may cause a fast temperature rise of the hydraulic fluid, and, if combined with an inoperative fuel tank inerting system, could lead to an uncontrolled overheat of the hydraulic fluid, possibly resulting in ignition of the fuel-air mixture of the affected fuel tank. See the MCAI for additional background information.

FMI: www.regulations.gov