TM 1-1520-238-10 8-10 Change 10 8.14 BEFORE STARTING APU – CPG. *1. MASTER CAUTION panel – Check that the fol- lowing are illuminated. a. LOW RPM ROTOR. b. ENG 1 OUT. c. ENG 2 OUT. 2. MASTER CAUTION panel: PRESS TO TEST – Check that all caution/warning lights illuminate. 3. Caution/warning panel – Check that the follow- ing segments are illuminated. a. PRI HYD. b. UTIL HYD. c. MAN STAB (BATT). d. MAIN XMSN 1. e. MAIN XMSN 2. f. ENG 1. g. ENG 2. h. ELEC SYS FAIL (BATT). i. ENG ANTI ICE. j. ADS (EXT PWR). k. TADS (EXT PWR). 4. Engine instrument test panel switch – TST. Check engine/rotor instrument segment lights and digital display (888) illuminates. 8.15 STARTING ENGINES – EXTERNAL PRESSURIZED AIR SOURCE – PILOT. NOTE Control sweeps and BUCS self-test are not mandatory prior to external air start. If checks are desired, connect a 3000 psi ex- ternal hydraulic source to the primary hy- draulic system to accomplish the checks. 1. External air source – Connected to helicopter. 2. Pressurized air – Verify available at helicopter. 3. Control locks – Remove. L4. Engines – Start same as normal (refer to para- graph 8.20). 5. GEN 1 and GEN 2 switches – GEN 1 and 2. 6. EXT PWR/BATT switch – To BATT if external power used for start. 7. External power – Disconnect. 8. External air source – Disconnect. 9. Continue with AFTER STARTING APU – Pilot and CPG (refer to paragraphs 8.17 and 8.18). *8.16. STARTING APU – PILOT. NOTE During cold weather starts at temperatures below 0 F (–18 C), the 95% switch is used to manually prevent PTO clutch engage- ment until the APU has reached 95% N_G. Prior to normal clutch engagement, place and hold the spring loaded 95% switch to the 95% position. When the APU ON advi- sory light illuminates, release the switch to allow clutch engagement. This procedure prevents shut down of the APU at low speeds under extreme cold conditions. 1. Fire guard – Posted, if available. 2. APU – Start as follows: a. APU switch – Set to RUN, pause, set to START, then release. b. APU FAIL caution light – Within 5 seconds of start, check extinguished. c. APU ON caution light – Check that light illu- minates. 3. GEN 1 and GEN 2 switches – GEN 1 and 2. NOTE ENGINES ONLY When the generators are placed ON, an er- roneous TGT indication or a mismatch be- tween pilot and CPG TGT gauges may oc- cur. The indicated TGT will be accurate when the actual TGT, minus the 71 C bias equals a positive number. 4. Control locks – Remove. 5. EXT PWR/BATT switch – Set to BATT if exter- nal power was used for start. 6. External power – Disconnect. EXT PWR caution light should be off.