EASA AD CF-2023-33
Ice and Rain Protection — Air Data Probes and Sensors — Heater Current Monitor Unit Failure Detection
Summary
Canadian Airworthiness Directive CF-2023-33 addresses ice and rain protection issues related to air data probes and sensors on Bombardier Inc. BD-100-1A10 aircraft, serial numbers 20003 through 20936. This directive mandates modifications to the heater current monitor units to detect failures and update flight manual procedures accordingly. The directive aims to enhance safety by ensuring reliable ice protection and accurate air data indications.
What Changed
CF-2023-33 introduces a requirement to install an external monitoring circuit with relays to detect heater current monitor unit failures that could cause unannunciated loss of ice protection on air data probes. It also requires revising the Airplane Flight Manual to include new normal and non-normal procedures related to air data heat failures. These changes address a single point failure in the programmable logic device controlling heater functions.
Why It Matters
This directive is critical for operators and maintenance teams as it prevents potential misleading airspeed and other flight data caused by undetected heater failures on air data probes. Compliance ensures improved crew awareness through alerting systems and updated procedures, reducing risks associated with ice accumulation. It supports regulatory compliance and enhances overall flight safety for affected Bombardier Challenger 300 and 350 aircraft.
What To Do
Operators must complete the required modifications and relay installations as specified in the applicable Bombardier Service Bulletins within 60 months from the effective date of May 24, 2023. After modification, the Airplane Flight Manual must be revised according to Transport Canada-approved procedures, and flight crews must be informed of these changes. Operational testing must also be performed to verify proper function of the new monitoring system.
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