Airworthiness Directives; The Boeing Company Model 737-700, -700C, -800, and -900ER Series Airplanes, Model 747-400F Series Airplanes, and Model 767-200 and -300 Series Airplanes

Résumé

We propose to adopt a new airworthiness directive (AD) for certain Model 737-700, -700C, -800, and -900ER series airplanes, Model 747-400F series airplanes, and Model 767-200 and -300 series airplanes. This proposed AD would require an inspection for affected serial numbers of the crew oxygen mask stowage box units; and replacement of the crew oxygen mask stowage box unit with a new crew oxygen mask stowage unit, if necessary. This proposed AD results from reports indicating that certain crew oxygen mask stowage box units were possibly delivered with a burr in the inlet fitting. The burr may break loose during test or operation and may pose an ignition source or cause an inlet valve to jam. We are proposing this AD to prevent an ignition source, which could result in an oxygen-fed fire; or could cause an inlet valve to jam in a crew oxygen mask stowage box unit, which could result in restricted flow of oxygen.