EASA AD 26-120
Electrical Power – Emergency Electrical Network Management Unit – Modification / Re-Identification
Summary
EASA Airworthiness Directive PAD No. 26-120 is a proposed directive addressing the Emergency Electrical Network Management Unit (EENMU) on Airbus A350-941 and A350-1041 aeroplanes. It targets specific EENMU part numbers that may have incorrect firmware logic affecting the electrical power distribution system. The directive applies to all manufacturer serial numbers except those with Airbus modification 120968 incorporated during production.
What Changed
This proposed AD introduces a mandatory modification and re-identification of affected EENMU parts to correct the firmware logic at the FPGA function level. It requires replacement of affected units with serviceable parts following Airbus Service Bulletins and prohibits installation of affected parts after modification. The AD also mandates concurrent or prior modification of the aeroplane configuration as specified in related Airbus service bulletins.
Why It Matters
The incorrect control logic in the EENMU can cause loss of all alternating current busbars on one emergency side under certain failure conditions, potentially compromising essential electrical power availability. This poses a safety risk by reducing electrical system redundancy critical for safe flight and landing. Compliance ensures continued airworthiness and operational safety of affected Airbus A350 aircraft.
What To Do
Operators must replace each affected EENMU with a serviceable part within 78 months from the AD's effective date, following Airbus-approved instructions. They must also perform any required aeroplane configuration modifications as per Airbus Service Bulletins A350-24-P028 or A350-24-P046 before or concurrently with the EENMU replacement. After modification, installation of affected parts is prohibited.
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