EASA AD 2024-0024
THOMMEN AIRCRAFT EQUIPMENT AG: Navigation — Digital Air Data Computer — Replacement
Summary
EASA Airworthiness Directive 2024-0024 is issued for Thommen Aircraft Equipment AG AC32 Digital Air Data Computers installed on aircraft including the AW 189, Pilatus PC-21, and Cessna 550, among others with Supplemental Type Certificates. The directive addresses a known issue with certain AC32.() digital air data computers that may stop functioning at temperatures below -20°C. It mandates the replacement of affected units to ensure continued safe navigation data provision.
What Changed
This new airworthiness directive requires the removal from service and replacement of affected AC32.() digital air data computers identified by specific part and serial numbers. It also restricts installation to only serviceable parts, which include units that have had their power modules replaced according to Thommen Service Bulletin AC32/07. The directive introduces compliance requirements within 12 months of its effective date.
Why It Matters
The directive is critical for aviation professionals because the affected digital air data computers can fail in cold conditions, potentially leading to insufficient navigational data and reduced aircraft control. Operators and maintenance organizations must ensure compliance to maintain airworthiness and flight safety. Compliance teams need to track affected serial numbers and manage part replacements to avoid operational disruptions.
What To Do
Operators of Group 1 aircraft must remove and replace affected AC32.() digital air data computers within 12 months from 7 February 2024, following Thommen's Service Bulletin AC32/07 instructions. Installation of affected parts is prohibited from the effective date unless the power module has been replaced as specified. Stakeholders should coordinate with Thommen Aircraft Equipment AG for rectification and maintain records of compliance.
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