Airworthiness Directives; The Boeing Company Airplanes

We are adopting a new airworthiness directive (AD) for all The Boeing Company Model 787-8 and 787-9 airplanes. This AD was prompted by a flight test report indicating that the crew oxygen masks in the flight deck did not deploy correctly. This AD requires an inspection at four locations in the flight deck to determine whether any crew oxygen mask having a certain part number is installed, and replacement of affected crew oxygen masks. We are issuing this AD to address the unsafe condition on these products.