EASA AD 2021-0123-E
Hydraulic Power — Tail Rotor Load Compensator — Functional Check / Modification
Summary
EASA Airworthiness Directive 2021-0123-E is an emergency directive affecting Airbus Helicopters AS 350 B, B2, B3, and BA models with specific serial numbers. It addresses a wiring non-conformity in the tail rotor load compensator hydraulic system that could lead to loss of hydraulic power and potential loss of helicopter control. The directive mandates a functional check and modification of the hydraulic system wiring to ensure safe operation.
What Changed
This new emergency AD introduces a prohibition on hydraulic off training and requires a one-time functional check of the main rotor and tail rotor servo actuator solenoids. If discrepancies are found, corrective wiring modifications using a retrofit kit must be performed. Additionally, all affected helicopters must be modified within 150 flight hours to correct the wiring issue.
Why It Matters
This directive is critical for aviation professionals because it addresses a safety risk that could cause loss of tail rotor hydraulic control during emergency procedures or training. Operators and maintenance teams must comply to prevent potential loss of helicopter control, ensuring continued airworthiness and regulatory compliance. The operational restriction on hydraulic off training impacts pilot training programs until compliance is achieved.
What To Do
Operators must immediately cease hydraulic off training as specified in the Flight Manual Supplement SUP.7 and place a cockpit placard to that effect. Within 15 flight hours or 7 days from 11 May 2021, a functional check of the hydraulic solenoids must be performed. If faults are found, corrective wiring modifications must be done before the next flight. All affected helicopters must be modified within 150 flight hours or by the effective date plus 150 flight hours, whichever is later, to fully comply with the AD.
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