Time Limits / Maintenance Checks — Airworthiness Limitation Section — Tension Torsion Straps — Storage Life Limit
- Published
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- Deadline
AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Operators must replace affected Bendix and Lord TT-Straps within specified compliance times based on storage and total life limits, with deadlines ranging from immediate replacement to within two months or during the next inspection period. Installation of Bendix TT-Straps is prohibited from the effective date, and Lord TT-Straps may only be installed if their storage life does not exceed five years. All replacements must follow Airbus Helicopters Alert Service Bulletin instructions.
Summary
EASA Airworthiness Directive 2021-0122 addresses the storage life limits of Tension Torsion (TT) Straps installed on Airbus Helicopters Deutschland GmbH MBB-BK117 helicopter models including A-1, A-3, A-4, B-1, B-2, C-1, C-2, and D-2. The directive focuses on the ageing of elastomeric materials in Bendix and Lord TT-Straps, which may compromise structural integrity and helicopter control. It mandates compliance with storage life limits and removal of certain Bendix TT-Straps to ensure continued airworthiness.
What changed
EASA Airworthiness Directive 2021-0122 introduces storage life limits for Bendix and Lord TT-Straps used on MBB-BK117 helicopters, requiring replacement of straps exceeding specified storage and total life thresholds. It prohibits installation of Bendix TT-Straps and restricts installation of Lord TT-Straps to those with storage life not exceeding five years. This is a new regulation establishing mandatory storage life limits and replacement schedules.
Why it matters
This directive is critical for operators and maintenance organizations to prevent premature failure of TT-Straps, which could lead to loss of helicopter control. Compliance ensures structural integrity of rotor components and adherence to continuing airworthiness requirements. It impacts maintenance planning, parts inventory management, and installation practices for affected helicopter models.
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