AD 2021-20-13 Requires Repetitive Lubrication And Repetitive Detailed Visual Inspections

The FAA is adopting a new airworthiness directive (AD) for certain Bombardier, Inc., Model CL-600-2B16 (604 Variant) airplanes.

This AD was prompted by multiple reports of cracking of the main landing gear (MLG) shock strut lower pin. This AD requires repetitive lubrication and repetitive detailed visual inspections (DVI) and non-destructive test (NDT) inspections of the MLG shock strut lower pins, and replacement if necessary. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective November 18, 2021.

Supplementary Information: Transport Canada Civil Aviation (TCCA), which is the aviation authority for Canada, has issued TCCA AD CF-2020-54R1, dated December 23, 2020 (TCCA AD CF-2020-54R1) (also referred to after this as the Mandatory Continuing Airworthiness Information, or the MCAI), to correct an unsafe condition for certain Bombardier, Inc., Model CL-600-2B16 (604 Variant) airplanes. You may examine the MCAI in the AD docket at www.regulations.gov by searching for and locating Docket No. FAA-2021-0462.

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain Bombardier, Inc., Model CL-600-2B16 (604 Variant) airplanes. The NPRM published in the Federal Register on June 14, 2021 (86 FR 31453). The NPRM was prompted by multiple reports of cracking of the MLG shock strut lower pin part number (P/N) 19146-3. The subsequent investigation concluded that the friction torque when the shock strut is under compression loading, causes the pin anti-rotation tangs to become loaded beyond their load carrying capability. This overload condition can result in pin fracture originating at the base of the pin anti-rotation tang. Inadequate lubrication aggravates the condition. The NPRM proposed to require repetitive lubrication and repetitive DVI and NDT inspections of the MLG shock strut lower pins, and replacement if necessary. The FAA is issuing this AD to address cracking of the MLG shock strut lower pin. If not addressed, this condition could result in structural failure of one or both MLG. See the MCAI for additional background information.

FMI: www.regulations.gov