400W Series Installation Manual Page 2-11190-00356-02 Rev. G2.6 Cabling and Wiring ConsiderationsWiring should be installed in accordance with AC 43.13-1B Chapter 11. For dual 400W Series unitinstallations, care should be taken to ensure separation between wires of redundant systems to reduce thepossibility of loss of navigation due to a single event. When wire separation cannot be achieved, thefollowing issues should be addressed:• It should not be possible for a cable harness to be exposed to wire chafing in a manner that bothGPS units fail simultaneously;• The cable harness should not be located near flight control cables and controls, high electricalcapacity lines or fuel lines;• The cable harness should be located in a protected area of the aircraft (e.g., isolated from enginerotor burst); and• Do not route cable near high-energy sources.NOTEWiring which is required to be shielded per Appendix H must be shielded. Pigtail lengths mustbe less than 3.0 inches.Refer to Section 3.7 and Section 3.8 for connector and tooling information.Refer to Section 3.10 for recommended coax cable.Refer to Appendix H for the appropriate wiring connections to assemble the wiring connector.Once the cable assemblies have been made, attach the cable connectors to the rear connector plate. Afterinstalling the mounting tube, attach the assembled connector plate. Route the wiring bundle asappropriate. Use 22 to 24 AWG wire for all connections except for power. Use 20 AWG for power andground. Avoid sharp bends.2.7 Air Circulation and CoolingThe 400W Series units meet all TSO requirements without external cooling. However, as with allelectronic equipment, lower operating temperatures extend equipment life. On the average, reducing theoperating temperature by 15° to 20°C (27° to 36°F) doubles the mean time between failure (MTBF).Recommended airflow rating is 1 CFM (cubic foot per minute) at a pressure equivalent to 0.1 inches ofwater.Potential damage to your 400W Series unit may occur by using outside forced air to cool the equipment.Therefore, it is recommended that an electric forced air fan be installed, of the indicated rating, to coolthis equipment.Units tightly packed in the avionics stack heat each other through radiation, convection, and sometimesby direct conduction. Even a single unit operates at a much higher temperature in still air than in movingair. Fans or some other means of moving the air around electronic equipment are usually a worthwhileinvestment. A 5/8 inch diameter air fitting is provided on the rear of the mounting rack for the purpose ofadmitting cooling air under such conditions. If a form of forced air cooling is installed, make certain thatrainwater cannot enter and be sprayed on the equipment.2.8 Compass Safe DistanceAfter reconfiguring the avionics in the cockpit panel, if the 400W Series unit is mounted less than 12inches from the compass, recalibrate the compass and make the necessary changes for noting correctiondata.
