EASA AD CF-2021-42
Engine Controls — Binding of Fuel Control Unit Push Rod End Bearings
Summary
Canadian Airworthiness Directive CF-2021-42 addresses the issue of binding in the fuel control unit (FCU) push rod end bearings on Viking Air Ltd. DHC-6 series 1 through series 400 aircraft, specifically those with lower FCU push rod assemblies part numbers C6CE1398-7, C6CE1398-3 with P/N VSC30-3A rod end bearings, or FAA PMA equivalents. The directive mandates inspections, functional checks, lubrication, and replacement with redesigned parts to prevent engine power control issues. This AD aims to ensure continued safe operation of affected aircraft by mitigating the risk of engine power reduction failure.
What Changed
This new Airworthiness Directive introduces mandatory initial and repetitive functional checks, special detailed inspections, lubrication, and replacement of affected FCU push rod assemblies with redesigned parts. It also prohibits installation of the affected FCU push rod assemblies as replacement parts. The directive incorporates compliance with Viking Service Bulletin V6/0063 and its revisions.
Why It Matters
The directive is critical for aviation professionals because binding of the FCU push rod bearings can lead to an inability to reduce engine power, potentially causing in-flight engine shutdowns and increased pilot workload during critical flight phases. Operators and maintenance organizations must comply to maintain aircraft airworthiness and prevent safety risks associated with engine control failures.
What To Do
Operators must perform initial functional checks, inspections, and lubrication of affected FCU push rod assemblies within 125 flight hours or 30 days from the effective date of 2021-12-10. Repetitive checks and lubrication must continue at specified intervals, and any detected deficiencies require immediate replacement with approved serviceable parts. Installation of affected assemblies as replacements is prohibited from the effective date onward.
AI-generated summary from official EASA source document. Always verify against the original.