Summary
The FAA proposes to adopt a new airworthiness directive (AD) for certain Boeing Model 777 airplanes. This proposed AD would require an inspection to determine the manufacturer and manufacture date of the oxygen masks in the center and outboard passenger service units (PSUs), crew rests, and lavatory and flight attendant oxygen boxes, as applicable. This proposed AD would also require related investigative/ corrective actions if necessary. This proposed AD results from a report that several passenger masks with broken in-line flow indicators were found following a mask deployment. We are proposing this AD to prevent the in-line flow indicators of the passenger oxygen masks from fracturing and separating, which could inhibit oxygen flow to the masks and consequently result in exposure of the passengers and cabin attendants to hypoxia following a depressurization event.