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:
Several operators have reported difficulties in opening the airstair door. Investigation revealed that the airstair door gearbox drain paths were blocked by sealant, causing water to accumulate and freeze in the gearbox assembly. An airstair door that is unable to be opened could hinder evacuation in the event of an emergency.
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The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.