Federal Aviation Administration February 2, 2007 – Federal Register Recent Federal Regulation Documents

This supplemental NPRM revises an earlier proposed airworthiness directive (AD) for PW JT9D-7R4G2 series turbofan engines. That proposed AD would have required replacing the old configuration 2nd stage high pressure turbine (HPT) air seal assembly with a new design 2nd stage HPT air seal assembly that increases cooling air flow. That proposed AD resulted from a report of an uncontained failure of the 2nd stage HPT air seal assembly, caused by the air seal assembly brace disengaging from the air seal, due to insufficient cooling air flow. This supplemental NPRM revises the proposed AD by proposing to include additional models of the PW JT9D-7R4 turbofan engines in the applicability, requiring a visual and a fluorescent penetrant inspection of the air seal assembly, replacing the 2nd stage HPT vane assemblies, and reopening the comment period. This NPRM results from comments to the proposed AD. We are proposing this AD to prevent uncontained failure of the 2nd stage HPT air seal assembly, leading to engine in-flight shutdown and damage to the airplane.

This amendment amends Standard Instrument Approach Procedures (SIAPs) for operations at certain airports. These regulatory actions are needed because of changes occurring in the National Airspace System, such as the commissioning of new navigational facilities, addition of new obstacles, or changes in air traffic requirements. These changes are designed to provide safe and efficient use of the navigable airspace and to promote safe flight operations under instrument flight rules at the affected airports.