AD 2020-25-02 Requires Replacing Certain NLG Door Attachment Bolts With Serviceable Bolts

The FAA is adopting a new airworthiness directive (AD) for all Saab AB, Support and Services Model 340A (SAAB/SF340A) and SAAB 340B airplanes; and Model SAAB 2000 airplanes.

This AD was prompted by reports that certain nose landing gear (NLG) door attachment bolts are susceptible to hydrogen embrittlement. This AD requires replacing certain NLG door attachment bolts with serviceable bolts, as specified in a European Union Aviation Safety Agency (EASA) AD, which is incorporated by reference. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective January 21, 2021.

Supplementary Information: The EASA, which is the Technical Agent for the Member States of the European Union, has issued EASA AD 2020-0149, dated July 7, 2020 (EASA AD 2020-0149) (also referred to as the Mandatory Continuing Airworthiness Information, or the MCAI), to correct an unsafe condition for all Saab AB, Support and Services Model 340A (SAAB/SF340A) and SAAB 340B airplanes; and Model SAAB 2000 airplanes.

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to all Saab AB, Support and Services Model 340A (SAAB/SF340A) and SAAB 340B airplanes; and Model SAAB 2000 airplanes. The NPRM published in the Federal Register on September 15, 2020 (85 FR 57168). The NPRM was prompted by reports that certain NLG door attachment bolts are susceptible to hydrogen embrittlement. The NPRM proposed to require replacing certain NLG door attachment bolts with serviceable bolts, as specified in an EASA AD.

The FAA is issuing this AD to address NLG door attachment bolts that were incorrectly manufactured and are susceptible to hydrogen embrittlement, decreasing the mechanical characteristics. This condition could lead to failure of the affected parts, which would impair the link between the NLG and NLG door and could prevent the extension or retraction of the NLG, and cause consequent damage to the airplane and possible loss of control during landing. See the MCAI for additional background information.

FMI: www.regulations.gov