EASA AD US-2021-05-11
Flight Controls - Spoiler Control Module - Operational Test
Summary
Federal Aviation Administration Airworthiness Directive 2021-05-11 is a final rule addressing certain Boeing Company Model 757 airplanes. It mandates repetitive operational tests of the spoiler inhibit function and, for some airplanes, installation of new relay bracket assemblies, wiring changes to spoiler control modules (SCMs), installation of new SCMs, and clearance measurements. This directive aims to improve lateral handling qualities during approach and landing by mitigating unwanted lateral oscillations.
What Changed
This AD supersedes AD 2017-26-10 and introduces repetitive operational tests of the spoiler inhibit function. It requires new hardware installations, wiring modifications, and clearance measurements for certain Boeing 757 airplanes. Additionally, it clarifies service bulletin instructions and includes on-condition actions to address potential unsafe conditions.
Why It Matters
This AD is critical for operators and maintenance teams to prevent unwanted lateral oscillations during landing, which could lead to over-control and compromise safe flight and landing. Compliance ensures improved lateral handling qualities and reduces the risk of pilot-induced oscillations. It also updates maintenance procedures to align with the latest safety standards.
What To Do
Affected operators must perform the required repetitive operational tests and, where applicable, install new relay bracket assemblies, modify wire bundles, install new SCMs, and measure clearances as specified. On-condition actions must be completed if issues are found. Compliance with this AD is mandatory by April 19, 2021.
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