Federal Aviation Administration November 23, 2005 – Federal Register Recent Federal Regulation Documents

The FAA is adopting a new airworthiness directive (AD) for all Airbus Model A318-100, A319-100, A320-200, A321-100, and A321-200 series airplanes, and Model A320-111 airplanes. This AD requires an inspection to determine whether certain braking and steering control units (BSCUs) are installed or have ever been installed. For airplanes on which certain BSCUs are installed or have ever been installed, this AD requires an inspection of the nose landing gear (NLG) upper support and corrective action if necessary, and a check of the NLG strut inflation pressure and an adjustment if necessary. For some of these airplanes, this AD also requires a revision to the aircraft flight manual to incorporate an operating procedure to recover normal steering in the event of a steering failure. This AD results from a report of an incident where an airplane landed with the NLG turned 90 degrees from centerline. We are issuing this AD to prevent landings with the NLG turned 90 degrees from centerline, which could result in reduced controllability of the airplane.

This NPRM proposes new rules that will require operators and manufacturers of transport-category airplanes to take steps that, in combination with other required actions, should greatly reduce the chances of a catastrophic fuel-tank explosion. The proposal follows seven years of intensive research by the FAA in collaboration with industry into promising technologies designed to make fuel tanks effectively inert, thus preventing electrical and other systems from igniting flammable vapors in the fuel tank ullage (vapor space). The result of that research is that fuel tank inerting, originally thought to be prohibitively expensive, can now be accomplished in a reasonably cost-effective fashion and protect the public from future calamities which, we have concluded, are otherwise virtually certain to occur. The new rules, if adopted, would not actually direct the adoption of specific inerting technology either by manufacturers or operators but would establish a performance-based set of requirements that do not specifically direct the use of fuel-inerting but rather set acceptable levels of flammability exposure in tanks most prone to explosion or require the installation of an ignition mitigation means in an affected fuel tank. Technology now provides a variety of commercially feasible methods to accomplish these vital safety objectives.

The FAA is adopting a new airworthiness directive (AD) for certain Boeing Model 767-300 series airplanes. This AD requires replacing the frequency converters used to supply power for medical and galley utility outlets with modified frequency converters, and related actions. This AD results from a report indicating that a hard short circuit condition between the output of certain frequency converters and their downstream circuit breakers will produce a continuous output current that could cause the undersized output wiring to overheat when the frequency converters fail to shut off. We are issuing this AD to prevent overheating of the output wiring of the frequency converters, which could result in the failure of a wire bundle and consequent adverse effects on other systems sharing the affected wire bundle.