EASA AD 26-085
Navigation – GLU-2100 Global Navigation Satellite System Clock Oscillator – Operational Limitation
Summary
EASA Airworthiness Directive PAD No. 26-085 is a proposed directive addressing an operational limitation for the GLU-2100 Global Navigation Satellite System Clock Oscillator installed on Airbus A350-941 and A350-1041 aeroplanes. It identifies certain affected GLU-2100 units with specific part and serial numbers that may cause erroneous aircraft position information without warning. The directive applies to all manufacturer serial numbers of these aircraft models.
What Changed
This new proposed Airworthiness Directive introduces a prohibition on operating any Airbus A350 aeroplane equipped with an affected GLU-2100 unit and forbids installation or reinstallation of these parts. It requires identification and modification of affected parts as per Collins Aerospace Vendor Service Bulletin GLU-2100-34-B. No affected parts are currently installed on any aircraft, so no compliance time is required beyond the effective date.
Why It Matters
This directive is critical for aviation professionals because the affected GLU-2100 units can cause inaccurate GNSS outputs, potentially leading to incorrect aircraft position data being presented to flight crews without alert. Operators and maintenance organizations must ensure affected parts are not installed or operated to maintain flight safety and regulatory compliance. Early identification and replacement prevent integration issues with the aircraft's Air Data Inertial Reference Unit (ADIRU).
What To Do
From the effective date of the directive, operators must not operate any Airbus A350-941 or A350-1041 aeroplane with an affected GLU-2100 part installed and must not install such parts. Maintenance teams should replace any affected parts with compliant units following the aircraft maintenance manual and Collins Aerospace service bulletin instructions. Comments on the proposed directive must be submitted by 29 July 2026.
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