Airworthiness Directives; Learjet Model 45 Airplanes

This amendment adopts a new airworthiness directive (AD) that is applicable to certain Learjet Model 45 airplanes. This action incorporates a reduced life-limit replacement interval for certain shear pins in the trunnion assemblies of the main landing gears (MLG) into the airworthiness limitations section of the Instructions for Continued Airworthiness, and requires replacement of those certain shear pins with new, improved shear pins. This action is necessary to prevent failure of the shear pins in the trunnion assemblies of the MLGs, which could result in the collapse of a MLG, and consequent reduced controllability of the airplane during takeoff or landing. This action is intended to address the identified unsafe condition.