AD 2022-23-01 Prompted By Reports Of Wear On Fuel Couplings, Bonding Springs, And Sleeves...

The FAA is superseding Airworthiness Directive (AD) 2020-04-20, which applied to certain De Havilland Aircraft of Canada Limited Model DHC-8-400 series airplanes.

AD 2020-04-20 required repetitive inspections of certain parts for discrepancies that meet specified criteria, and replacement as necessary; repetitive inspections of certain parts for damage and wear, and rework of parts; and electrical bonding checks of certain couplings. AD 2020-04-20 also required revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations. For certain airplanes, AD 2020-04-20 allowed a modification that terminates the repetitive inspections. This AD continues to require the actions in AD 2020-04-20, revises the applicability by adding airplanes, and requires, for certain airplanes, the previously optional rework and retrofit of certain parts of the fuel system. Doing the rework and retrofit terminates the retained initial and repetitive inspections in this AD. This AD was prompted by reports of wear on fuel couplings, bonding springs, and sleeves as well as fuel tube end ferrules and fuel component end ferrules, and by a determination that a more robust lightning ignition protection design is necessary. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective December 13, 2022.

Supplementary Information: The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 to supersede AD 2020-04-20, Amendment 39-19857 (85 FR 17473, March 30, 2020) (AD 2020-04-20). AD 2020-04-20 applied to certain De Havilland Aircraft of Canada Limited Model DHC-8-400 series airplanes. AD 2020-04-20 required repetitive inspections of certain parts for discrepancies that meet specified criteria, and replacement as necessary; repetitive inspections of certain parts for damage and wear, and rework of parts; and electrical bonding checks of certain couplings. AD 2020-04-20 also required revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations. For certain airplanes, AD 2020-04-20 allowed a modification that terminated the repetitive inspections. The FAA issued AD 2020-04-20 to address wear on fuel couplings, bonding springs, and sleeves as well as fuel tube end ferrules and fuel component end ferrules, which could reduce the integrity of the electrical bonding paths through the fuel line and components, and ultimately lead to fuel tank ignition in the event of a lightning strike.

The NPRM published in the Federal Register on June 9, 2022 (87 FR 35128). The NPRM was prompted by AD CF-2017-04R3, dated April 1, 2020, issued by Transport Canada Civil Aviation (TCCA), which is the aviation authority for Canada (referred to after this as the MCAI). The MCAI states that wear has been detected on fuel couplings, bonding springs, and sleeves as well as fuel tube end ferrules and fuel component end ferrules. The MCAI also states that a more robust lightning ignition protection design is necessary. The MCAI states that such wear could reduce the integrity of the electrical bonding paths through the fuel line and components, and ultimately lead to fuel tank ignition in the event of a lightning strike.

You may examine the MCAI in the AD docket at regulations.gov under Docket No. FAA-2022-0672.

In the NPRM, the FAA proposed to continue to require the actions in AD 2020-04-20, revise the applicability by adding airplanes, and require, for certain airplanes, the previously optional rework and retrofit of certain parts of the fuel system.

The FAA issued a supplemental notice of proposed rulemaking (SNPRM) to amend 14 CFR part 39 to supersede AD 2020-04-20. The SNPRM published in the Federal Register on August 31, 2022 (87 FR 53424) (the SNPRM). The SNPRM was prompted by the FAA's determination that the NPRM inadvertently limited the proposed new terminating rework and retrofit to airplanes that had accomplished certain service information. In addition, the FAA determined that the optional terminating action specified in AD 2020-04-20, and corresponding credit, should be carried over to this AD. In the SNPRM, the FAA proposed to continue to require the actions in AD 2020-04-20, revise the applicability by adding airplanes, and require, for certain airplanes, the previously optional rework and retrofit of certain parts of the fuel system. The FAA is issuing this AD to address the unsafe condition on these products.

FMI: www.regulations.gov