Universal FMS Common Battery Failures

January 2010

The Universal Flight Management System (FMS) has two batteries. One, located on the CPU board, supports Flight Plans while the other, located on the GPS board, supports the Almanac. During the initial start up, it is not uncommon to get a CPU Fail, Data Bus Fail or Ram Fail on the Universal FMS. Many times these are caused by one of the two FMS batteries being low and nearing the end of its useful life.

You begin to see these batteries fail after about three years of service. It is alway good practice to have them replaced within three years to avoid failures while on the road. A low battery will allow the system to continue working while displaying messages. However, if a battery is allowed to go completely dead before being changed, it will cause the system to stop during its self-test and display a red CPU Data Bus Fail. It will not allow the system to proceed until a new battery is installed.

On a FMS with only the Control Display Unit (CDU), the batteries are located in the CDU. On a FMS with both a CDU and Navigation Computer Unit (NCU), the batteries are located in the NCU.

For further information on Universal component maintenance battery replacement or to schedule maintenance, contact one of Duncan Aviation’s Avionics Technical Reps at 800.562.6377.

Components Tech Reps

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. Direct: 402.479.8112 Mobile: 402.432.0154

Campbell, Curt - Avionics Tech Rep - Lincoln, NE (LNK). Aviation professional since 1975. Airframes: Challenger, Hawker, Learjet, King Air, Global Air Data Computer, Auto Pilot Systems, EFIS, Roll Modules, Mode Couplers and Selectors, Static Inverters, Servos, Spoiler System, Tool Calibration Lab, Flight Guidance Computer, Cabin Displays, and EFD Components and Systems Specialist. Direct: 402.479.4220 Mobile: 402.416.8832

Magnus, Dan - Avionics Tech Rep - Lincoln, NE (LNK). Aviation professional since 1976. Airframes: Citation, Embraer, Gulfstream, Hawker, King Air ADF, Comms, Control Heads, CVR, DME Gables Control Heads, Receivers, Nav-Comm/Receivers, Radar Systems, GPS, GNS, Transponders and UNS Components and Systems Specialist. Direct: 402.479.4217 Mobile: 402.416.1870

Schultz, Gerry - Avionics Tech Rep - Lincoln, NE (LNK). Aviation professional since 1965. Airframes: Hawker, King Air Instrumentation, Vertical and Directional Gyros, Airspeed Indicators, HSI, ADI, Encoders, Course Indicator, Rate Gyro, Directisyn, Vertisyn, RMI and Pitot Static Components and Systems Specialist. Direct: 402.479.4212 Mobile: 402.416.4742

Troyer, Larry - Avionics Tech Rep - Lincoln, NE (LNK). Aviation professional since 1982. Airframes: Astra, Falcon, Hawker, King Air, Westwind Air Data Computer, Auto Pilot Systems, EFIS, Roll Modules, Mode Couplers and Selectors, Static Inverters, Servos, Spoiler System, Cabin Displays, and EFD Components and Systems Specialist. Direct: 402.479.4219 Mobile: 402.416.8835

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