AD 2021-23-02 Prompted By Reports Of Loss Of Hydraulic Fluid And Annunciation Of The Check Fire Detect Light

The FAA is adopting a new airworthiness directive (AD) for certain De Havilland Aircraft of Canada Limited Model DHC-8-401 and -402 airplanes.

This AD was prompted by reports of loss of hydraulic fluid and annunciation of the check fire detect light. This AD requires doing a detailed visual inspection for chafing and proper clearance of the left-hand (LH) and right-hand (RH) main landing gear (MLG) primary zone advanced pneumatic detector (APD) sensing lines, the hydraulic tube assemblies, and the surrounding structure, and doing all applicable corrective action. The FAA is issuing this AD to address the unsafe condition on these products. This AD is effective January 5, 2022.

Supplementary Information: Transport Canada Civil Aviation (TCCA), which is the aviation authority for Canada, has issued TCCA AD CF-2021-12, dated April 14, 2021 (also referred to as the Mandatory Continuing Airworthiness Information, or the MCAI), to correct an unsafe condition for certain De Havilland Aircraft of Canada Limited Model DHC-8-401 and -402 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-2021-0656.

The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 CFR part 39 by adding an AD that would apply to certain De Havilland Aircraft of Canada Limited Model DHC-8-401 and -402 airplanes. The NPRM published in the Federal Register on August 12, 2021 (86 FR 44324). The NPRM was prompted by reports of loss of hydraulic fluid and annunciation of the check fire detect light. The NPRM proposed to require doing a detailed visual inspection for chafing and proper clearance of the LH and RH MLG primary zone APD sensing lines, the hydraulic tube assemblies,  and the surrounding structure, and doing all applicable corrective actions. The FAA is issuing this AD to address insufficient separation between the APD sensing line and surrounding components, which could lead to a hydraulic leak, loss of hydraulic systems, and loss of fire detection in the MLG primary zone shouldprolonged contact occur. See the MCAI for additional background information.

FMI: www.regulations.gov