TM 55-1520-240-T 13-1.4  HEATING AND VENTILATING SYSTEM OPERATIONAL CHECK 13-1.4 INITIAL SETUP Equipment Condition: Applicable Configurations: TM 55-1520-240-23: All Battery Connected Tools: Electrical Power On Stopwatch Hydraulic Power Off Materials Heater Air Inlet Protective Shield Removed None Heater Exhaust Outlet Protective Shield Removed Visual Check of Heating and Ventilating System Personnel Required: Performed Medium Helicopter Repairer References: TM 55-1520-240-23 TASK RESULT 1. Check that CABIN HEATER CONT circuit breaker (1) is If circuit breaker (1) is open, close it.  If it opens again, go closed. to Task 13-1.5. 2. Check that CABIN HEATER BLOWER circuit breaker If circuit breaker (2) is open, close it.  If it opens again, go (2) is closed. to Task 13-1.6. WARNING Cockpit   vents   must   be   closed   before   vent blower  or  heater  is  started.    After  blower  or heater    is    started    open    vents    slowly    to prevent dirt and debris being blasted into air and eyes of personnel. 3. Check that DEFOG or DEFROST AIR CONTROL If handle (3) is up, push it down. handle (3) is all way down. 4. Check that PULL FOR COCKPIT AIR knob (4) on pilot If either knob (4) is out, push it in. and copilot instrument panel is against panel. 5. Set RIGHT SIDE FWD and AFT MAIN FUEL PUMPS R FUEL PRESS capsule (7) shall go out.  If it stays on, go switches (5 and 6) to ON. to Task 10-2.4. 6. Set heater fan switch (8) to VENT.  Blower only. Heater fan shall run.  If it can not be heard, go to Task 13-1.7. 7. Slowly pull out DEFOG or DEFROST AIR CONTROL Air shall be felt flowing from pilot and copilot jettisonable handle (3). door defroster ducts (9) and nose bubble vents (10).  If air flow is not felt at ducts or vents, go to Task 13-1.8. 8. Slowly pull out PULL FOR COCKPIT AIR knob (4)  on Air shall be felt flowing from pilot's outlet (11).  If air flow is pilot's instrument panel. not felt, go to Task 13-1.9. 9. Slowly pull out PULL FOR COCKPIT AIR knob (4) on Air shall be felt flowing from copilot's outlet (11).  If air flow copilot's instrument panel. is not felt, go to Task 13-1.9. 10.    Slowly pull out CABIN AIR AIR CONTROL handle Air shall be felt flowing out cabin vents (13).  If air flow is (12). not felt, go to Task 13-1.10. 11.    Set heater fan switch (8) to HEATER ON. Heater fan shall stop. 12.    Turn CABIN TEMP SELECTOR knob (14) to WARMER. TASK RESULT 13.    Press and release HEATER START switch (15). Heater fan shall be heard.  After about 10 seconds, NOTE combustion shall occur and warm air shall flow from all vents Heater will not operate if cabin thermostat and ducts.  If heater fan can not be heard, go to Task 13-1.11. senses a temperature of 34° C (93° F) or greater. If heater fan is running but warm air is not flowing from ducts or vents, go to Task 13-1.12.  If HEATER HOT (Without 74)  HTR HOT (With 74) capsule (16) comes on, go to Task 13-1.13. 14.    Turn CABIN TEMP SELECTOR (14) to COLDER posi- Cooler air shall be felt flowing from ducts and vents.  If air tion. doesn't get cooler or air gets hotter, go to Task 13-1.14. 15.    Set heater fan switch (8) to off (center). Heater fan shall run until heater cools down.  If fan is not running after heater is turned off, go to Task 13-1.15. 16.    Set RIGHT SIDE FWD and AFT MAIN FUEL PUMP switches (5 and 6) to OFF. FOLLOW-ON MAINTENANCE: TM 55-1520-240-23: Electrical power off. Battery disconnected. GO TO NEXT PAGE 13-6  Change 23