TM 55-1520-240-T 15-1.5  APU OPERATIONAL CHECK (Continued) 15-1.5 TASK RESULT If BITE indicators do not remain black, go to task 15-2.8. If fuel boost pump cannot be heard operating, go to task 15-2.9. CAUTION If a roar is heard and a flame is seen at APU exhaust during APU start, shut down APU to prevent AP U damage. CAUTION If there is no hydraulic pressure in 30 seconds after APU switch is released to RUN, shut down APU. CAUTION If APU is to be restarted or another start attempt tried, wait at least 30 sec- onds after APU has stopped before set- ting APU switch to START.  This allows residual fuel to drain from APU, thereby preventing overspeed or overtemp con- dition. 7. Set APU switch (8) to START for a minimum of APU shall begin to motor and accelerate to running speed 2 seconds then release it to RUN. within 30 seconds.  ESU (7) BITE indicators shall se- NOTE quence from all black to all white, then all black.  APU ON capsule (9) shall come on.  UTIL HYD SYS capsule (10) Observe ESU bite indicators sequencing shall go out.  If roar is heard and flame is seen at APU during start.  Note last two sequences when exhaust (hot start), shut down APU to prevent damage automatic shutdown occurs.  Do not move and go to task 15-6.17. APU switch until bite indications are recorded unless hot start occurs.   If APU does not motor, go to task 15-2.10. If APU motors but does not start or starts and automati- cally shuts down, check ESU bite indicators and refer to table 15-2.2 for maintenance action. If APU runs and ESU bite is black but APU ON capsule is not on, go to task 15-2.13. If APU runs and UTIL HYD SYS capsule (10) does not go out, shut down APU and go to task 7-2.4. TASK RESULT 8. Set APU GEN switch (11) to ON.   NO.  1 RECT OFF and NO.  2 RECT OFF (Without 74) and RECT 2 (With  74)capsules (12 and 13) shall go out. APU ON capsule (9) shall stay on.  If capsules do not go out, go to task 9-1.4.  If APU capsule goes out, check ESU bite indicators and refer to table 15-2.2 and/or task 15-2.14. 9. Set POWER XFR NO.  1 and POWER XFR NO.  2 NO.  1 HYD FLT CONTR and NO.  2 HYD FLT CONTR switches (5 and 6) to ON. (Without 74) or RECT 1 and RECT 2 (With  74) cap- sules (14 and 15) shall go out.  If not, go to task 7-2.15. APU ON capsule (9) shall stay on.  If it goes out, check ESU bite indicators and refer to table 15-2.2. 10.    Open then close APU CONT NORM circuit breaker APU ON capsule (9) shall stay on.  If it goes out, go to task (3).   15-2.11. 11.    Open then close APU CONT EMERG circuit breaker (4). APU ON capsule (9) shall stay on.  If it goes out, go to task 15-2.11. 12.    Set POWER XFR NO.  1 and POWER XFR NO.  2 NO.  1 HYD FLT CONTR and NO.  2 FLT CONTR (Without switches (5 and 6) to OFF. 74) or RECT 1 and RECT 2 (With 74) capsules (14 and 15) shall come on. 13.    Set APU GEN switch (11) to OFF.   NO.  1 RECT OFF and NO.  2 RECT OFF (Without 74) or RECT 1 and RECT 2 (With  74) capsules (12 and 13) shall come on.  APU shall remain running.  If APU shuts down, go to task 15-2.15. 14.    Set APU switch (8) to OFF.   APU shall shut down.  APU ON capsule (9) shall go out.  If APU does not shut down, go to task 15-2.12. CAUTION Cycling of the APU switch during APU coastdown may cause the APU to re- start with a possible overtemperature. FOLLOW-ON MAINTENANCE: TM 55-1520-240-23: Battery disconnected. Electrical power off. END OF TASK Change 23  15-17/(15-18 blank)