Airworthiness Directives; Learjet Model 45 Airplanes

We are adopting a new airworthiness directive (AD) for certain Learjet Model 45 airplanes. For certain airplanes, this AD requires repetitive inspections for chafing and other damage of the case drain tube from the hydraulic pump case installed on the left-hand engine, and corrective action if necessary. This AD also requires, for all airplanes, repetitive inspections for discrepancies of the left engine's nacelle tubing, repetitive inspections for evidence of fluid leakage within the left engine accessory compartment, and corrective actions if necessary. This AD was prompted by reports of chafed hydraulic tubes in the left-hand engine. We are issuing this AD to detect and correct chafed hydraulic tubes in the left-hand engine and consequent hydraulic tube failure and uncontrolled loss of flammable fluid within the engine cowling, which could result in a fire in the engine nacelle and loss of control of the airplane.