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:
[T]he occurrence of drill marks [has been found] at the lower ring region of the rear pressure bulkhead between [the] circumferential splice joint and rear skin located between stringers 12 and 13. These marks may result in formation of fatigue cracks accelerated by corrosion reducing the structural strength of the rear pressure bulkhead, which may cause a sudden decompression of the passenger cabin.
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The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.