Federal Aviation Administration June 22, 2011 – Federal Register Recent Federal Regulation Documents

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD would require either replacement of the stabilator horn assembly or repetitive inspection of the stabilator horn assembly for corrosion or cracks with replacement of the stabilator horn assembly if any corrosion or cracks are found. This proposed AD was prompted by reports of cracks developing in the stabilator horn assembly. We are proposing this AD to detect and correct corrosion or cracks in the stabilator horn assembly. Corrosion or cracks could lead to failure of the stabilator horn. Consequently, failure of the stabilator horn could lead to a loss of pitch control in flight.

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD would require inspecting to determine whether a third Halon fire extinguisher bottle is installed in the auxiliary power unit (APU) fragment impact zone, revising the limitations section of the airplane flight manual to add restrictions for APU usage for certain airplanes having a third fire extinguisher bottle, and removing the third fire extinguisher bottle from certain airplanes. This proposed AD was prompted by notification from the airplane manufacturer that the third fire extinguisher bottle is mounted in a small-fragment impact zone. We are proposing this AD to prevent penetration of the bottle by fragments released due to a failure of the APU rotor system. The bottle could rupture and cause substantial damage to primary airframe structure and primary flight controls.

We propose to adopt a new airworthiness directive (AD) for the products listed above. This proposed AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as: * * * * * A recent analysis conducted by the manufacturer showed a particular risk for explosive failure of the * * * hydraulic accumulator. This condition, if not detected and corrected, might, for some aeroplane installations, lead to damage to all three hydraulic circuits, possibly resulting in loss of control of the aeroplane or could, for certain other aeroplane installations, lead to an undetected fire in the wheel bay. * * * * * The proposed AD would require actions that are intended to address the unsafe condition described in the MCAI.

We are superseding an existing airworthiness directive (AD) that applies to the products listed above. This AD results from mandatory continuing airworthiness information (MCAI) originated by an aviation authority of another country to identify and correct an unsafe condition on an aviation product. The MCAI describes the unsafe condition as: