Powerplant - Engine Fan Cowl Spring Door Opening System Actuator - Replacement
- Published
- Effective
- Deadline
AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Affected operators must replace each SDOS actuator with the redesigned part and verify the installation of updated safety markers by September 3, 2021. They must also prohibit installation of affected actuator part numbers on these aircraft. Compliance requires following Boeing Service Bulletin 737-71-1911 RB, Revision 1, dated September 10, 2020, and maintaining records of compliance.
Summary
Federal Aviation Administration Airworthiness Directive 2021-13-18 is a final rule addressing all Boeing Company Model 737 airplanes powered by LEAP-1B engines, including the 737-8, 737-9, and 737-8200 models. It targets the replacement of the engine fan cowl spring door opening system (SDOS) actuator due to safety concerns involving inadvertent spring energy release causing injury to maintenance personnel. The directive mandates installation of redesigned SDOS actuators with improved joints and clearer safety markers.
What changed
This new airworthiness directive requires replacing affected SDOS actuators with redesigned units that use blind rivets instead of pins and include enhanced safety markers. It expands applicability to all Boeing 737 models powered by LEAP-1B engines, not just the 737-8 and 737-9. The AD also mandates verification of proper installation of new safety markers on the actuators.
Why it matters
This AD is critical for aviation professionals because it addresses a hazardous condition that can cause injury during maintenance due to sudden actuator extension or part separation. Operators and maintenance teams must ensure compliance to prevent accidents and maintain aircraft safety. The directive also prevents reintroduction of unsafe actuators during future replacements, supporting ongoing airworthiness.
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