TM 1-1520-238-T-5 7–121 7–40. TAIL WHEEL LOCK ACTUATOR – DOES NOT UNLOCK TAIL WHEEL 7–40 Tools: Nomenclature Part Number Tool Kit, Electrical SC518099CLA06 Repairer’s Multimeter, Digital AN/PSM-45 Personnel Required: 68X Armament/Electrical Systems Repairer (2) References: TM 1-1520-238-23 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. 1. On pilot center circuit breaker panel, check TWHL LOCK circuit breaker. Does circuit breaker stay closed? YES Go to step 2. NO Go to paragraph 7–41. 2. With TAIL WHEEL switch in UNLOCK position, check for 28 VDC at P754–A. Is voltage present? YES Go to step 3. NO Go to step 6. 3. Check for open between P754–B and GS682–F. Does open exist? YES Repair open wire between P754–B and GS682–F. Go to paragraph 7–21. NO Go to step 4. 4. On pilot caution/warning panel, check OIL LOW UTIL HYD indicator. Is OIL LOW UTIL HYD indicator illuminated? YES Go to step 5. NO Replace tail wheel lock control valve (TM 1-1520-238-23). 5. Shut down AGPU (TM 1-1520-238-23). Check utility hydraulic system for leaks. Do leaks exists? YES Repair leaking components (TM 1-1520-238-23). NO Service utility manifold reservoir (TM 1-1520-238-23). Go to paragraph 7–21. 6. Check for open between J527–A14 and J527–A15. Does open exist? YES Replace TAIL WHEEL switch (TM 1-1520-238-23). NO Go to step 7. 7. Check for 28 VDC at P527–A14. Is voltage present? YES Repair open wire between P527–A15 and P754–A. Go to paragraph 7–21. NO Repair open wire between P527–A14 and CB59–2. Go to paragraph 7–21. END OF TASK