Airworthiness Directives; Airbus Model A300 B4-600, B4-600R, and F4-600R (Collectively Called A300-600) Series Airplanes, and Airbus Model A310 Series Airplanes

This amendment adopts a new airworthiness directive (AD), applicable to certain Airbus Model A300 B4-600, B4-600R, and F4-600R (collectively called A300-600) series airplanes, and Airbus Model A310 series airplanes. This AD requires replacement of Honeywell inertial reference units (IRU) with new or modified Honeywell IRUs. For certain airplanes, this proposal also would require replacement of Litton IRUs, mode selector units (MSU), and an inertial sensor display unit (ISDU) with new Honeywell IRUs, MSUs, and a new ISDU. This action is necessary to prevent loss of positioning data and a display of incorrect attitude data, which could compromise the ability of the flightcrew to maintain the safe flight and landing of the airplane. This action is intended to address the identified unsafe condition.