Airworthiness Directive · Amendment 39-12257 · Learjet Model 55 Series Airplanes and Model 60 Airplanes
Learjet Model 55 Series Airplanes and Model 60 Airplanes
Model 55 series airplanes, serial numbers 55-003 through 55-147 inclusive, and Model 60 airplanes, serial numbers 60- 002 through 60-189 inclusive; certificated in any category.
This amendment adopts a new airworthiness directive (AD), applicable to certain Learjet Model 55 series airplanes and Model 60 airplanes, that requires replacement of the brake valve adjustment screw with a new improved screw, and for certain airplanes, it would also require installation of a new brake valve lever stop. The actions specified by this AD are intended to prevent bottoming of the valve components before contact of the brake valve lever with the stop, which could result in loss of all hydraulic fluid and consequent loss of normal braking. This action is intended to address the identified unsafe condition.
The aircraft, engines and makers this AD names, by the model designations in its text. A model listed here may still be outside the AD's serial ranges.
Aircraft
