Pneumatic System — Wing Check Valve Bleed Air Leak - Replacement
- Published
- Effective
- Deadline
AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Operators must remove and replace the affected V-band clamps and check valve seals within 48 months or 8000 flight hours from April 12, 2021, whichever occurs first. Additionally, from the directive's effective date, the old parts referenced as DSC361-250 and MS35769-71 are prohibited from installation as spares. Maintenance teams should follow the procedures outlined in the latest revision of De Havilland Service Bulletin 84-36-06.
Summary
The Canadian Airworthiness Directive CF-2021-11 addresses a pneumatic system issue involving bleed air leaks at the wing check valve on De Havilland DHC-8-401 and DHC-8-402 aircraft, serial numbers 4001 and 4003 through 4624. This directive mandates replacement of specific V-band clamps and check valve seals to prevent air leaks that could damage aircraft structure and critical components. It applies to affected aircraft operated under Canadian aviation regulations.
What changed
CF-2021-11 introduces a mandatory replacement of V-band clamps and check valve seals on the wing bleed air system with newly designed parts to prevent leaks. It also prohibits installation of the previously used parts as spares from the effective date. This is a new directive responding to multiple in-service reports of air leaks and detection system failures.
Why it matters
This directive is critical for operators and maintenance organizations to prevent potentially hazardous bleed air leaks that could damage the aircraft wing structure, emergency landing gear cables, and static air temperature sensors. Compliance ensures continued airworthiness and safety of the affected DHC-8-400 series aircraft. It also helps avoid costly repairs and operational disruptions caused by undetected leaks.
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