NEW DEVELOPMENTS IN ORGANIZED WIRE SYSTEMS

Currently at Sikorsky Aircraft, the method for wire interconnects is via bundled wire harnesses. Using this method, each wire has to be individually cut, coded, routed, and terminated. This assembly process is both labor intensive and provides ample opportunity for quality issues to arise such as: mislocated pins in the connectors, defective crimps, incorrect selection of coded wires, and damage caused during insulation stripping. In addition, this type of electrical interconnection is bulky, heavy, difficult to shield, and costly. Due to many constraint requirements (such as space and ease of maintenance) placed upon Sikorsky Aircraft for the next generation aircraft, (RAH-66 Comanche), the development of alternatives to existing wire harnesses was needed. The needs of minimizing cost and weight, as well as improving space utilization, are also primary contributing factors for this change. Organized wire systems (OWS) were introduced to address these weight and limited space problems. OWS uses the concept of arranging the wires in a planar array. During the design phase, particular attention is paid to reducing crosstalk (Electro-magnetic Interference) or EMI. Flat harnesses allow the designer flexibility by strategically placing the signals within the array. This provides separation needed to meet crosstalk EMI requirements. When more stringent EMI characteristics are necessary, a layer of copper foil shielding surrounds the cable. OWS wiring uses either a woven cable, a film bonded cable, or an extruded cable where a plastic substrate coats the wires to keep them arranged in a flat pattern. This flat pattern allows for the harness to be placed in smaller and tighter routing paths. In addition, analysis of rectangular connectors, specifically mass terminable was considered for further space reduction and manufacturing efficiencies. While reviewing OWS for its design advantages a number of related manufacturing benefits developed. This paper and presentation addresses these manufacturing gains as well as looking at how Sikorsky has refined film bonded cable to maximize the gains flat ribbon cable can provide. It will briefly discuss the existing interconnect manufacturing process as a baseline, then highlight advancements such as: mass insulation stripping, computer programmed and controlled connector termination, and the routing of up to 20 wires at a time. Also addressed are enhancements such as improved maintenance and supportability, elimination of wire coding, and improving EMI shielding by wrapping the cable bundles with foil instead of costly braided shields and braided protective coverings.