Federal Aviation Administration November 3, 2010 – Federal Register Recent Federal Regulation Documents

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.

We are superseding an existing airworthiness directive (AD) for the products listed above. That AD currently requires removing certain propeller hubs from service at new, reduced life limits and eddy current inspections (ECIs) of the propeller hub. This new AD requires removing certain propeller hubs from service before they exceed 6,000 hours time-since-new (TSN). This AD was prompted by a report of a crack in a propeller hub. We are issuing this AD to prevent cracked propeller hubs, which could cause failure of the propeller hub, blade separation, and loss of control of the airplane.