Airworthiness Directives; De Havilland Aircraft of Canada Limited (Type Certificate Previously Held by Bombardier, Inc.) Airplanes

摘要

The FAA proposes to supersede Airworthiness Directive (AD) 2020-04-20, which applies to certain De Havilland Aircraft of Canada Limited Model DHC-8-400 series airplanes. AD 2020-04-20 requires 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 requires revising the existing maintenance or inspection program, as applicable, to incorporate new or more restrictive airworthiness limitations. For certain airplanes, AD 2020-04-20 allows a modification that would terminate the repetitive inspections. Since the FAA issued AD 2020-04-20, the FAA has determined that a more robust lightning ignition protection design is necessary and that additional airplanes are affected by the unsafe condition. This proposed AD would 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. Doing the rework and retrofit would terminate the