Engine Fuel & Control — Hydro-mechanical Metering Unit / Drive Link Splines — Inspection
- Published
- Effective
- Deadline
- Replaces
- 2013-0082
- Replaces
- 2020-0033
AI-generated summary of the official EASA document. Verify against the PDF before acting.
What to do
Operators must inspect and clean the drive gear shaft splines and sleeve assembly of Group 1 and Group 2 HMUs within specified compliance times, then at intervals not exceeding 500 HMU operating hours. Any discrepancies found require immediate corrective action before flight. Installing a Group 3 HMU with SAFRAN mod TU139 is an optional terminating action to repetitive inspections. Compliance began with the original issue effective 10 March 2020, and the revision effective 17 December 2021.
Summary
EASA Airworthiness Directive 2020-0033R1 is an updated safety directive addressing the inspection of hydro-mechanical metering units (HMU) and drive link splines on SAFRAN Helicopter Engines ARRIUS 2 series engines. These engines are commonly installed on helicopters such as the Airbus Helicopters Deutschland EC135, Leonardo A109, and KAMOV 226T. The directive mandates inspections to prevent engine in-flight shutdowns caused by spline deterioration on the HMU drive shaft.
What changed
This revision removes inspection and cleaning requirements for HMUs with the improved design incorporating SAFRAN modification TU139. It introduces the option to install improved HMUs as a terminating action to repetitive inspections. The directive also updates compliance instructions referencing the latest SAFRAN Mandatory Service Bulletin version K.
Why it matters
This directive is critical for aviation professionals to prevent engine failures due to HMU spline wear, which can lead to forced landings and potential injuries. Operators and maintenance organizations must ensure compliance to maintain aircraft airworthiness and safety. The updated AD provides clearer guidance and an option to reduce inspection frequency by installing improved parts.
More for Safran ARRIUS 2
All 18- EASA AD 2026-0131Engine Fuel & Control – Electronic Engine Control Unit – Software Update; Engine Fuel & Control – Preference Injector – Non-extinguishing Test / ReplacementJul 6, 2026
- EASA AD 2026-0027Time Limits / Maintenance Checks — Airworthiness Limitations Section — AmendmentFeb 11, 2026
- EASA AD 2024-0202R1Engine Fuel & Control — Fuel Control Unit — ReplacementSep 8, 2025
- EASA PAD 25-138WITHDRAWN - EXPLANATORY STATEMENT ATTACHEDSep 5, 2025
- EASA AD 2024-0218R1-CN
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New ADs and bulletins for Safran ARRIUS 2, Airbus Helicopters EC135, Leonardo A109 and Kamov 226T, summarized like this page, every Monday.