Action
Notice of proposed rulemaking (NPRM).
Summary
We propose to adopt a new airworthiness directive (AD) for certain Learjet Inc. Model 60 airplanes. This proposed AD was prompted by a report of a high-speed rejected takeoff caused by all four main landing gear (MLG) tires blowing out during the takeoff roll. This proposed AD would require installing new rigid hydraulic tube assemblies to the MLG struts, installing a new MLG squat switch bracket, modifying the MLG squat switch wire harness, modifying the MLG anti-skid wheel transducer electrical wire harnesses, routing and securing the anti-skid wheel and squat switch electrical wire harnesses to the MLG strut assembly; installing outboard bracket assemblies, anti-skid shield, forward electrical cover on the forward stiffener, upper and lower inboard bracket assemblies, and clamps that support the electrical wire harness; modifying the aft stiffener for the new electrical wire harness support; installing the aft electrical cover and strap on the aft stiffener; installing a new flat landing light lamp if necessary; and, for certain airplanes; installing a new wheel speed detect box assembly, nutplates, and brackets and a new thrust reverser interface box, and modifying the wiring for the new thrust reverser interface box. We are proposing this AD to prevent failure of the braking system or adverse operation of the spoiler and thrust reverser system due to external damage, particularly from tire failure, which could result in loss of control of the airplane.