Summary
We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as:
During flight-testing of a wing anti-ice piccolo tube containing a deliberate small breach, it was determined that the wing leading edge thermal switches Part Number (P/N) 601R59320-1 were not detecting the consequent bleed leak at the design threshold. As a result, Airworthiness Limitation (AWL) tasks, consisting of a functional check of the wing leading edge thermal switches (P/N 601R59320-1) and an inspection of the wing anti-ice duct piccolo tubes on aeroplanes with these switches installed, have been introduced. These tasks will limit exposure to dormant failure of the wing leading edge thermal switches in the event of piccolo tube failure, which could potentially compromise the structural integrity of the wing leading edge and the effectiveness of the wing anti-ice system.
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The unsafe condition is loss of control of the airplane. The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.