EASA AD 2025-0004: Flight Controls — Rudder Travel Limitation Unit Logic — Modification

What to do

Operators must modify affected ATR 42 and ATR 72 aeroplanes within 12 to 24 months depending on the group classification, following the instructions in the applicable ATR service bulletins. After modification, required tests must be completed before the next flight, and any discrepancies must be reported to ATR for corrective instructions. Additional work is required within 750 flight hours or 6 months for aircraft previously modified under original service bulletin issues.

Summary

EASA Airworthiness Directive 2025-0004 is an airworthiness directive affecting ATR 42-400, ATR 42-500, and various ATR 72 series aeroplanes. It addresses a modification to the rudder travel limitation unit logic to improve flight control safety. The directive applies to aircraft without certain ATR modifications embodied in production and requires specific service bulletin compliance.

What changed

This new directive introduces a modification involving the installation of one or two relays and associated wiring to enhance the rudder travel limitation unit's command and monitoring logic. It corrects an identified erroneous behavior in the Core Processing Module 2 affecting rudder deflection at high speeds. The directive also mandates additional work for aircraft previously modified under earlier service bulletin versions to ensure proper maintenance procedure compliance.

Why it matters

This directive is critical for aviation professionals because it addresses a potential unsafe condition where rudder deflection may not be properly limited at high speeds, risking loss of aircraft control. Operators and maintenance organizations must ensure compliance to maintain aircraft airworthiness and safety. The modification improves reliability of flight control systems, directly impacting operational safety and regulatory compliance.

What to do

Summary

What changed

Why it matters

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