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Learjet 40/45 Model End Cap Replacement

November 2010

According to AW 32-053, Learjet is planning on releasing a Temporary Revision (TR) to Chapter 5 on November 29, 2010, that will reduce the life limit of the end cap (P/N 200-0303), per IRN 3220013. This is a straight replacement, not a different P/N or Service Bulletin. Since the same P/N is being installed, the reduced life limit will remain the same. The reduced life limit is 2,387 landings for FAA registered aircraft and 1,988 landings for EASA registered aircraft. There is a 25 landing grace period that commences upon the release of the TR.

Due to contractual issues between Learjet and Heroux, Duncan Aviation can no longer purchase parts to repair or reseal actuators and/or struts on the 40/45 model aircraft; and can no longer perform the 8-year inspections on the 40/45 MLG struts and actuators.

Actuator Internal Leakage Test

Duncan Aviation in Battle Creek, Michigan, and Lincoln, Nebraska, are only authorized to replace the P/N 200-0303 end caps and will perform an incoming internal leakage test to identify any actuators that will need repaired beyond the scope of our authorizations. If an internal leakage is discovered, the actuator will be shipped to Learjet in Wichita, Kansas, for full repair. Otherwise, Duncan Aviation will perform the end cap replacement.

Actuator End Cap Replacement

The end cap replacement takes approximately 20-man hours in at least 16 clock hours. This includes: staging the aircraft in the hangar, removing the MLG actuators and transporting them to the shop. The actuators are tested to determine if the end cap is to be replaced or shipped to Wichita. After the end cap replacement is performed, the actuators will be re-installed and functionally tested, which will include a gear swing. The aircraft will then be down jacked and the Return to Service paperwork complied with.

Learjet Warranty

The Learjet warranty will cover the 20 man hours of labor but not the cost of the materials. The cost to the operator will be $0.36 per landing that has been USED on each of the actuators. The actuators are tracked separately. For illustration purposes only, if the actuator has one landing, the end cap will cost $0.36. If the actuator has 10,000 landings, the end cap will cost $3,600.

Learjet Fielded Program Procedure

Please be aware that this is a Fielded Program that must be coordinated through the Fielding Specialists in Wichita at 316-285-6555. The number of landings on each actuator, not necessarily the aircraft, must be reported when contacting the Fielding Specialists. The Fielding Specialists are coordinating with all the shops that are authorized to perform the end cap replacement daily to maximize capacity and hopefully minimize the impact to the customer. If an operator elects to drop-in at any service provider, not just Duncan Aviation, there is a chance that the service provider will not be able to procure the required parts, resulting in a wasted trip for the operator.

In conclusion, Learjet and Heroux are working on a different part number/ dash number end cap that hopefully should restore the life limit of these actuators back to 17,000 landings. That in turn will be another Fielded Program at that time.


Jerry Cable
Cable, Jerry - Accessory Tech Rep - Lincoln, NE (LNK). Aviation professional since 1991.

Airframes: Astra, Challenger, Citation, Embraer, Falcon, Gulfstream, Hawker, Learjet, King Air, Global, Westwind

Hydraulic equipment and pumps, Pneumatic valves, Wheel and Brake, Emergency Power Supplies, Electric Motors, Mechanical Actuators, Landing Gear and Accessory Components and Systems Specialist.

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