Airworthiness Directives; Boeing Model 747-200B, 747-300, and 747-400 Series Airplanes

The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 747-200B, 747-300, and 747-400 series airplanes. This AD requires an inspection to determine the manufacturer and manufacture date of the oxygen masks in the passenger service units of the outboard and center main deck, the flight attendant service units, flightcrew rest, upper and lower module of the door 5 overhead crew rest, lavatory modules, and miscellaneous ceiling panels, as applicable, and related investigative/corrective actions if necessary. This AD results from a report that several passenger masks with broken in-line flow indicators were found following a mask deployment. We are issuing 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.