Table 1-13. Accessory Functions

TM 55-4920-401-13&P Table 1-13. Accessory Functions. Index Number (Figure 4- Accessory Function — — 1 Switch Box During trim, permits thermocouple signal to be mon- itored on cockpit indicator or on tester. Used only with D’Arsonval indicators. 2 Junction Box Connects to heater cable and probes. Power distribution box for probes. Also combines signals from probe thermo- couples to obtain average thermocouple signal. 3 Heater Cable Connects to junction box. Supplies power from tester to heat probes. Also carries probe thermocouple signal to tester. 4 Check Cable Connects engine thermocouple signal to tester. 5 Instrument Cable Connects tester to a variety of adapters including re- sistance check adapter, insulation check adapter, indi- cator check adapter, RPM adapter, and RPM indicator adapter. 6 Extension Handle Where thermocouples are relatively inaccessible, exten- sion handle holds probes and allows them to be properly positioned. 7 Power Cable Supplies power to tester. 8 RPM Check Adapter During trim, supplies tach generator output to tester through instrument cable and to cockpit RPM indicator, simultaneously. Connects at tach indicator. 9 Insulation Check Adapter Connects through instrument cable to tester. Checks in- sulation resistance of complete aircraft thermocouple system. 10 EGT Indicator Check Connects through instrument cable to tester. Provides Adapter calibrated signal to check cockpit indicator. 11 Resistance Check Connects through instrument cable to tester. Checks re- Adapter sistance of complete aircraft thermocouple system. 12 Heater Probes Heat aircraft thermocouples. Probes include their own thermocouples which permit their temperatures to be in- dicated on the tester. Probes must be matched to engine thermocouples. Connect to junction box. 13, 14 Check Cable Adapter Adapts check cable to engine harness junction connector. 1-44