AD 2021-19-12 Prompted By Reports And A Design Review Indicating That There Could Be Possible Corrosion On The MLG

The FAA is adopting a new airworthiness directive (AD) for MHI RJ Aviation ULC Model CL-600-2C10 (Regional Jet Series 700, 701 & 702), CL-600-2C11 (Regional Jet Series 550), CL-600-2D15 (Regional Jet Series 705), CL-600-2D24 (Regional Jet Series 900), and CL-600-2E25 (Regional Jet Series 1000) airplanes.

This AD was prompted by reports and a design review indicating that there could be possible corrosion on the main landing gear (MLG) outer cylinder at the interface with the gland nut on the shock strut installation and on the forward and aft trunnion pins in the MLG dressed shock strut assembly. This AD requires detailed inspections for corrosion on the MLG outer cylinder assemblies, certain MLG dressed shock strut assemblies, and the MLG outer cylinder at the gland nut threads, thread relief groove, and chamfer; a detailed inspection for the presence of corrosion-inhibiting compound (CIC) on the MLG forward and aft trunnion pins and grease adapter assemblies; applicable corrective actions; application of primer, paint, and CIC as applicable; re-identification of certain part numbers; and marking of the MOD STATUS field of the nameplate of certain parts. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective November 10, 2021.

Supplementary Information: Transport Canada Civil Aviation (TCCA), which is the aviation authority for Canada, has issued TCCA AD CF-2019-17R1, dated June 18, 2020 (TCCA AD CF-2019-17R1, dated June 18, 2020) (also referred to as the Mandatory Continuing Airworthiness Information, or the MCAI), to correct an unsafe condition for MHI RJ Aviation ULC (type certificate previously held by Bombardier, Inc.) Model CL-600-2C10 (Regional Jet Series 700, 701 & 702) airplanes, Model CL-600-2C11 (Regional Jet Series 550) airplanes, Model CL-600-2D15 (Regional Jet Series 705) airplanes, CL-600-2D24 (Regional Jet Series 900) airplanes, and Model CL-600-2E25 (Regional Jet Series 1000) airplanes.

You may examine the MCAI in the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2021-0309. The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to MHI RJ Aviation ULC Model CL-600-2C10 (Regional Jet Series 700, 701 & 702), CL-600-2C11 (Regional Jet Series 550), CL-600-2D15 (Regional Jet Series 705), CL600-2D24 (Regional Jet Series 900), and CL-600-2E25 (Regional Jet Series 1000) airplanes. The NPRM published in the Federal Register on April 20, 2021 (86 FR 20461). The NPRM was prompted by reports and a design review indicating that there could be corrosion on the MLG outer cylinder assemblies and certain MLG dressed shock strut assemblies; primer was not correctly applied at the gland nut thread relief groove and chamfer areas on certain MLG outer cylinders during production; and CIC was inadvertently removed from certain MLG forward and aft trunnion pins and grease adapter assemblies during maintenance. The NPRM proposed to require detailed inspections for corrosion on the MLG outer cylinder assemblies, certain MLG dressed shock strut assemblies, and the MLG outer cylinder at the gland nut threads, thread relief groove, and chamfer; a detailed inspection for the presence of CIC on the MLG forward and aft trunnion pins and grease adapter assemblies; applicable corrective actions; application of primer, paint, and CIC as applicable; re-identification of certain part numbers; and marking of the MOD STATUS field of the nameplate of certain parts. The FAA is issuing this AD to address undetected corrosion on the MLG forward and aft trunnion pins, and the gland nut interface on certain MLG outer cylinders, which could result in an MLG collapse. See the MCAI for additional background information.

FMI: www.regulations.gov