TM 1-1520-238-10 2-19 Section II. EMERGENCY EQUIPMENT 2.14 GENERAL. Emergency equipment on the helicopter consists of fire extinguishing equipment and two first aid kits (fig 9-1). WARNING Exposure to high concentrations of fire extinguishing agent or decomposition products should be avoided. The gas should not be allowed to contact the skin; it could cause frostbite or low tem- perature burns. If agent comes in contact with skin, seek medical help immediate- ly. 2.15 PORTABLE FIRE EXTINGUISHER. A pressurized fire extinguisher is mounted on a quick re- lease support located in the FAB fairing aft of the right FAB door and above the main landing gear wheel (fig 2-2). It is accessible through a hinged access panel and the panel is marked FIRE EXTINGUISHER INSIDE. The fire extin- guisher compound is released by a hand-operated lever on top of the extinguisher. Inadvertent discharge of the bottle is prevented by a breakaway safety wire across the actuating lever. Operating instructions are printed on the extinguisher. 2.16 ENGINE AND AUXILIARY POWER UNIT (APU) FIRE DETECTION. Two optical sensors, which react to visible flames, are lo- cated in each engine compartment and in the APU compartment. Three pneumatic fire/overheat detectors are located in the aft deck area. One detector is mounted on the main transmission support, and one on each of the two firewall louver doors. Amplified electrical signals from the sensors located in the engine compartment will illumi- nate the respective ENG FIRE PULL handle (fig 2-15) in both crew stations. The APU compartment sensors, or the aft deck fire/overheat detectors, will illuminate the FIRE APU PULL handle (fig 2-15) in the pilot station and the FIRE APU segment on the MASTER CAUTION panel in both crew stations. The engine fire pull handles (ENG FIRE 1 PULL and ENG FIRE 2 PULL) are located in simi- lar positions in both crew stations; they are at the upper left corner of the instrument panel. The FIRE APU PULL handle is located on the APU panel on the pilot right con- sole. 2.16.1 Engine and APU Fire Detector Testing. FIRE PULL handle lamps are tested by pressing the PRESS TO TEST pushbutton on the MASTER CAUTION panel in either crew station. The fire detector circuits receive 28 vdc from the emergency dc bus through the FIRE DETR circuit breakers (ENG 1, ENG 2 and APU) on the pilot overhead circuit breaker panel (fig 2-39). The fire detector circuits are tested by turning the FIRE TEST DET rotary switch located on the pilots aft right console (fig 2-15). The switch is spring-loaded to OFF. When set at 1, the first sensor circuit for No. 1 engine, No. 2 engine, APU, and left and right firewall louver door fire detectors are tested, which causes all FIRE PULL handles to illuminate. The FIRE APU segments on both MASTER CAUTION panels also illuminate. When the FIRE TEST DET switch is set at 2, the second sensor circuit for No. 1 engine, No. 2 en- gine, APU, and main transmission support fire detector are tested; and all FIRE PULL handles and both FIRE APU MASTER CAUTION panel segments will illuminate. In either test, failure of a handle to light up indicates a fault in that particular sensor circuit. 2.17 ENGINE AND APU FIRE EXTINGUISHING SYSTEM The fire extinguishing agent is stored in two spherical bottles, each containing a nitrogen precharge. The bottles, designated as primary (PRI) and reserve (RES) are mounted on the fuselage side of the No. 1 engine fire- wall. Tubing is installed to distribute the extinguishing agent to either of the engine nacelles or to the APU compartment. Bottle integrity may be checked by inspect- ing the thermal relief discharge indicator which is viewed from below the left engine nacelle. A pressure gage on each bottle provides an indication of the nitrogen prechar- ge pressure. Each bottle has three discharge valves that can be individually actuated by an electrically ignited pyro- technic squib. There is one valve for each of the engine nacelles and one for the APU compartment. When a FIRE PULL handle is pulled, four events occur: fuel is shut off to the affected engine, engine cooling louvers to the affected engine close (not applicable to the APU), the appropriate squib firing circuit is armed, and the ENCU is shut off (not applicable to the APU). The extinguishing agent is not re- leased to the fire area, however, until the FIRE BTL switch, located near each fire pull handle, is activated. The FIRE BTL switch is first set at PRI (primary bottle). When the fire is extinguished, the light in the