Engine — Variable Stator Vane Actuating System — Check
- Published
- Effective
- Deadline
- Replaces
- 2017-0149
AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Operators must perform VSV travel checks within 12 months after 30 August 2017 and subsequently at intervals determined by measured load values, with a maximum interval of 12 months or as short as 3 months if higher loads are detected. If the load to move any actuation ring exceeds 445 Newtons, the engine must be removed from service and repaired or have the compressor front stator case replaced. Repair or replacement with marking 'RP031' terminates the need for repetitive checks. Installation of affected engines or compressor front stator cases requires compliance with these inspection requirements.
Summary
EASA Airworthiness Directive 2017-0149R1 is a regulatory document addressing the CFM International CFM56-3 series engines installed on Boeing 737-300, -400, and -500 aircraft. It mandates repetitive checks of the variable stator vane (VSV) actuating system to detect corrosion-related issues that could cause loss of engine thrust control. The directive provides instructions for inspection, corrective actions, and optional terminating actions to ensure continued airworthiness.
What changed
This revision of EASA AD 2017-0149 corrects the scope of Engine Shop Manual subtasks referenced for the VSV travel check, removing unrelated tasks and fixing a typographical error in a subtask number. It maintains the original requirements but clarifies and refines the inspection procedures and references to improve compliance accuracy.
Why it matters
This directive is critical for aviation professionals because it addresses a potential unsafe condition that could lead to engine thrust control loss due to corrosion in the high pressure compressor case. Operators and maintenance organizations must perform regular inspections and corrective actions to prevent engine failures and ensure flight safety. Compliance with this AD is mandatory to maintain aircraft airworthiness and regulatory approval.
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