SECTION III. GENERAL PROCEDURES

TM 1-1520-238-T-4 1–7 SECTION III. GENERAL PROCEDURES – SUMMARY 1–11. STARTING TROUBLESHOOTING 1–11 a. Determine the equipment to troubleshoot from the failure symptoms listed in TM 1-1520-238-T-2. NOTE If faulty equipment is not known and a failure symptom exists, use failure symptom list in TM 1-1520-238-T-2 to determine system. b. Select the chapter, section, and paragraph to use. (Refer to information on using this volume in HOW TO USE THIS VOLUME). c. For use of external power and the ground service utility connectors, refer to TM 1-1520-238-23. If external power is not available, refer to TM 1-1520-238-23 for the application of the auxiliary power unit (APU). Refer to TM 1-1520-238-23 and TM 55-1730-229-12 for application of external electrical and hydraulic power and pressurized air. External power is preferred however, for onboard power the APU may be used. d. During power up procedures, if circuit breakers do not stay closed refer to TM 1-1520-238-T-2 to identify the location of corrective procedures. e. During power up procedures, if power is not available to the equipment, refer to TM 1-1520-238-T-6 to troubleshoot the electrical system. f. Troubleshoot using specific procedures in the selected paragraph. 1–12. DURING TROUBLESHOOTING 1–12 WARNING · Turn off power before detaching or attaching wires and connectors. High current 28 VDC or 115 VAC is present. Failure to do so could result in death or serious injury. · To prevent injury, disable the aft avionics bay door fan before performing maintenance or troubleshooting in the aft avionics bay. CAUTION When making resistance, open, short, or other ohmmeter checks on circuits, always de–energize the circuit to avoid damage to the meter. a. Correct faults and repair any equipment where damage is obvious.