Air - Modulated Air System Control Valves - Lock-Out / Deactivation
- Published
- Effective
- Deadline
- Replaces
- 2021-0009
AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Operators must deactivate the MAS control valves on affected Trent 1000 engines within 50 flight cycles from first installation or within 30 days or 100 flight cycles after 15 January 2021, whichever is later, following Rolls-Royce Alert NMSB 75-AK642 instructions. Engines modified with SB 75-K778 are exempt from these requirements. Ferry flights of up to 3 flight cycles are permitted to position aircraft for maintenance.
Summary
EASA Airworthiness Directive 2021-0009R1 addresses the deactivation and lock-out of Modulated Air System (MAS) control valves on Rolls-Royce Trent 1000 series engines installed on Boeing 787 aircraft. The directive targets engines experiencing high wear on high pressure turbine triple seals, which could lead to turbine disc failure and potential damage to the aircraft. It mandates specific actions to deactivate the MAS control valves to mitigate this risk.
What changed
This revision of EASA AD 2021-0009 excludes Trent 1000 engines that have incorporated Rolls-Royce modification 75-K778 or Service Bulletin 75-K778 from the applicability of the directive. It also recognizes the embodiment of SB 75-K778 as an acceptable alternative method of compliance, which deactivates the MAS control valves without triggering spurious engine alert messages.
Why it matters
This directive is critical for aviation professionals to prevent potential engine failures caused by increased turbine cooling air leakage and seal fin wear. Operators and maintenance teams must ensure compliance to avoid unsafe conditions that could lead to in-flight engine damage and debris release. Understanding the updated applicability and alternative compliance methods helps streamline maintenance and operational decisions.
More for Rolls-Royce Deutschland Ltd & Co Kg TRENT 1000
All 59- EASA PAD 26-114Engine – High Pressure Turbine Blades – InspectionSep 24, 2026
- EASA AD 2026-0117R1Engine – Low Pressure Turbine Discs – InspectionAug 12, 2026
- EASA AD 2026-0143Engine – Intermediate Pressure Compressor Shaft Assembly / Front Air Seal – InspectionJul 20, 2026
- EASA AD 2026-0117Engine – Low Pressure Turbine Discs – InspectionJun 19, 2026
- EASA AD 2025-0206R1Engine — High Pressure Turbine Blades — InspectionDec 18, 2025
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New ADs and bulletins for Rolls-Royce Deutschland Ltd & Co Kg TRENT 1000 and Boeing 787, summarized like this page, every Monday.