Airworthiness Directive · Amendment 39-17497 · Landing gear
Learjet Inc. Airplanes
This AD applies to Learjet Inc. Model 60 airplanes, certificated in any category, serial numbers 60-001 through 60-413 inclusive.
We are adopting a new airworthiness directive (AD) for certain Learjet Inc. Model 60 airplanes. This 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 AD requires 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 issuing 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.
Within 600 flight hours or 12 months after the effective date of this AD, whichever occurs first: Do the actions required by paragraphs (g)(1), (g)(2), and (g)(3) of this AD, as applicable.
(1) For all airplanes: Install new rigid hydraulic tube assemblies to the MLG struts, install a new MLG squat switch bracket and modify the MLG squat switch wire harness, modify the MLG anti-skid wheel transducer electrical wire harnesses, and route and secure the anti-skid wheel and squat switch electrical wire harnesses to the MLG strut assembly, in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 60-32-33, dated July 23, 2012.
(2) For all airplanes: Install 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; modify the aft stiffener for the new electrical wire harness support; install the aft electrical cover and strap on the aft stiffener; and install a new flat landing light lamp, as applicable; in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 60-57-7, dated July 23, 2012.
(3) For airplanes having serial numbers 60-002 through 60-276 inclusive: Install a new wheel speed detect box assembly, nutplates, brackets, and interface box; and modify the wiring for the new thrust reverser interface box; in accordance with the Accomplishment Instructions of Bombardier Service Bulletin 60-78-7, Revision 2, dated May 1, 2006.
After accomplishing the actions required by paragraph (g) of this AD, the requirement in paragraph (h) of AD 2010-11-11, Amendment 39-16316 (75 FR 32255, June 8, 2010), to check the nose and main tire pressures before 96 hours prior to takeoff, is terminated. All provisions of paragraphs (g) and (h) of AD 2010-11-11 that are not specifically referenced by this paragraph remain fully applicable and must be complied with.
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
