Development & Implementation of an Electric Boring Process for the Frame Lug for Main Landing Gear Swing Link on the 777 Airplane

This paper discusses the process development and implementation of an Electric Boring process for boring the Frame Lug for the Main Landing Gear (MLG) Swing Link bushing on the 777 Airplane. Due to the process reliability issues associated with the equipment traditionally used for this process, primarily air driven right angle motors, a boring process using electric motors was developed and implemented for this application.

The process development focused on equipment selection based on horsepower/torque requirements, laboratory testing for cutting parameters and bore quality generation, equipment reliability testing under operational loads and process efficiency validation. The implementation programme involved the detail design and fabrication of protective enclosure (explosion proof) hardware to prevent the electric motor and its connections from being contaminated by various fluids used in processes in the vicinity of this application. This was mandated per the Fire & Safety regulations of the Boeing Company in its manufacturing operations. Production testing was carried out successfully with finish bore size meeting both the dimensional tolerance as well as the surface finish requirements for this application. An additional honing operation needed with the use of the traditional air driven motor process for meeting the finish size dimensional tolerances was eliminated with the switch to the electric motor boring process. Improved process efficiencies were realized due to the elimination of both the honing operation as well as the high downtime associated with constant breakdown of the air driven motors.

This effort is considered a breakthrough in bringing the electric motor technology to industrial line boring operations where Fire & Safety risks are high but can be eliminated with the detailed technical development of protective enclosures to prevent contamination of the electrical components and their connections. Additional applications for the use of this process both with the aircraft manufacturing processes as well as within the aircraft fleet support programmes are being targeted for development and implementation of this process.