The effects of mixed wire types in aircraft electrical wiring interconnection systems

Original publisher: Washington, D.C. : U.S. Dept. of Transportation, Federal Aviation Administration, Office of Aviation Research, [2005] OCLC Number: (OCoLC)62076582 Subject: Airplanes -- Electric wiring. Excerpt: ... It is generally accepted that the use of fewer parts on an aircraft will help to keep the overall costs down. The logistical costs of maintaining aircraft with multiple wire types and tooling are often cost prohibitive. OAMs prefer to use one wire type for all major wiring on the aircraft; however, special applications or environments may require that a different type of wire be used that can meet these special requirements. These various wire types will usually lay together in the same wiring runs and harnesses, or cross other wires. Since one wire length may pass through multiple areas of an aircraft with vastly different environmental conditions, the wire must be able to meet the most stringent of those application requirements. 3.2.2 Commercial Maintenance and Operator Wiring Practices. Maintenance facilities and operators usually follow the instructions and recommendations of the OAM for a specific airframe. Some facilities attempt to decrease parts inventories through standard process initiatives and may substitute parts through that process. In areas where modifications are made to the EWIS, mixing of wire types will occur if substitute wire types are used. Many of the older aircraft have airframe wire that is no longer allowed in the new 14 CFR Part 25 aircraft and is discouraged from use in aerospace applications. When repairs are made to the EWIS, these wires or portions of these wires could be replaced with alternative wire types. 3.2.3 Modification Facilities. Facilities that hold a Supplemental Type Certificate may perform modifications to the aircraft with different wire types than were originally used on the aircraft when approved by FAA authorities. 3.2.4 Military Maintenance and Operation Wiring Practices. As with many military ...