EASA AD 2016-0004R1
Engine Fuel & Control — Hydro-Mechanical Metering Unit — Inspection
Summary
EASA Airworthiness Directive 2016-0004R1 is an updated regulation addressing inspection requirements for the Hydro-Mechanical Metering Unit (HMU) on SAFRAN Helicopter Engines ARRIEL 2D engines, commonly installed on Airbus Helicopters AS 350 B3 and EC 130 T2 models. The directive mandates repetitive inspections and, if necessary, replacement of HMU components to prevent low fuel pressure warnings and potential engine shutdowns. It excludes engines with the post-mod TU 231 HMU from inspection requirements.
What Changed
This revision updates the previous AD 2016-0004 by incorporating the latest SAFRAN modifications, specifically excluding engines with the post-mod TU 231 HMU from inspection applicability. It also introduces editorial improvements to align with current AD writing standards without altering the core requirements. The directive continues to require inspections and replacements based on engine group classification and HMU operating hours.
Why It Matters
This AD is critical for aviation professionals to ensure the continued airworthiness and safe operation of ARRIEL 2D powered helicopters by preventing in-flight engine shutdowns caused by HMU component deterioration. Operators and maintenance organizations must adhere to the inspection intervals and corrective actions to mitigate risks associated with fuel pressure loss. Compliance ensures regulatory adherence and reduces the likelihood of emergency landings due to engine failure.
What To Do
Operators of ARRIEL 2D engines without the post-mod TU 231 HMU must perform inspections of the HMU inter-pump sleeve and pump splines before reaching specified operating hour thresholds and at regular intervals thereafter. Any detected discrepancies require immediate replacement of affected HMUs with serviceable units. Installation of post-mod TU 231 HMUs terminates the need for repetitive inspections. No HMU installations are allowed unless compliant with this AD from 20 January 2016 onward.
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