Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain The Boeing Company Model 787-8 and 787-9 airplanes. This proposed AD was prompted by reports that the cabin air compressor (CAC) outlet check valve failed due to fatigue of the aluminum flappers, and exposed the Y-duct to temperatures above its design limit. This proposed AD would require installing new inboard and outboard CAC outlet check valves on the left-side and right-side cabin air conditioning and temperature control system (CACTCS) packs. The FAA is proposing this AD to address the unsafe condition on these products.