Summary
This document proposes the supersedure of an existing airworthiness directive (AD), applicable to certain Learjet Model 45 airplanes, that currently requires repetitive application of grease to the rotating disk assembly of the nose landing gear (NLG) squat switch mechanism. This action would require replacement of the squat switch camrod of the NLG, which would terminate the repetitive application; and would also reduce the applicability of the exiting AD. This proposed AD is prompted by results of tests conducted by the airplane manufacturer. The actions specified by this proposed AD are intended to prevent moisture contamination and subsequent formation of ice which could cause bending and damage of the squat switch assembly, driving the nose wheel to an uncommanded angle against the force of the steering system. This condition, if not corrected, could result in the airplane departing the runway at high speeds during landing.