Digital electronic engine control (DEEC)/engine diagnostic unit (EDU) functional tester (DEFT) for the F100-PW-220/-229 engines

Automated test equipment does not need to be expensive to produce or occupy multiple equipment racks. By using commercial-off-the-shelf (COTS) circuit cards and customizing special functions in printed wiring assemblies, the costs of functionally testing Unit Under Test (UUT), such as the Digital Electronic Engine Control (DEEC) or the Engine Diagnostic Unit (EDU), can be reduced by 90 percent compared to conventional rack-and-stack methods. This paper describes the development and functionality of the DEEC/EDU Functional Tester (DEFT) as a low-cost test set. Unique DEFT features include: diagnostics test for UUTS, automated self test and calibration. The diagnostics software isolates failures to a Shop Replaceable Unit (SRU) providing the operator with recommendations to repair unit failures. The DEFT self-test consists of an external card that plugs into the computer interface, along with software to run the self test exercises on the computer. This provides a 100 percent level of confidence in the DEFT. The DEFT calibration system uses the self test card and specialized software, which prompts the operator for readings from a multimeter. These readings are used to calibrate a single channel which is then used to calibrate the remaining channels. All signals are generated internally using a single multimeter to calibrate all simulated DEEC/EDU interfaces.