APU FIRE EXTINGUISHING SYSTEM - DESCRIPTION AND OPERATION

Transcription

1 1.General APU FIRE EXTINGUISHING SYSTEM - DESCRIPTION AND OPERATION A.The APU fire extinguishing system has controls in two locations that release one application of fire extinguishing agent to a fire in the APU compartment. The system has test capability. B.The APU fire extinguishing system includes the APU fire extinguisher bottle located forward of the APU firewall, the APU/CARGO fire control panel on pilots' aft control stand P8, the P62 APU shutdown remote control panel on the nosegear, and the squib test panel located on the P61 right side panel. C.The APU shutdown remote control panel P62 is located on the nose landing gear. P62 contains a red APU FIRE LIGHT, APU SHT DN switch, and APU BTL DISCH switch. When a fire is detected in the APU compartment, the APU FIRE LIGHT comes on, and a warning horn sounds. Pressing APU SHT DN shuts down the APU and arms the remote APU bottle discharge. Pressing APU BTL DISCH switch discharges the APU fire bottle. If APU SHT DN switch is pressed, the APU remote fire indication power must be recycled OFF and ON to reset the system, otherwise fire horn is disabled. D. E. F. G. 2.Component Details ( Ref. Figure 1) A.APU Fire Extinguisher Bottle(s) (1)One APU fire extinguisher bottle is found forward of the APU fire wall on the lower right side. The extinguisher bottle includes a squib cartridge, pressure switch, and the combined safety relief and filler port. (2)One APU fire extinguisher bottle is found forward of the APU fire wall on the lower right side. The extinguisher Page 1 of 20

2 (3) bottle includes an active squib cartridge, pressure switch, and the combined safety relief and filler port. (4)The squib cartridge located on the discharge valve, when detonated, ruptures a retaining disc in the valve releasing the extinguishing agent. (5)The APU fire extinguisher bottle (p/n ) has two discharge ports. The system only utilizes one of the discharge ports. The bottle has both squibs fitted. The inactive, unconnected squib (p/n ) is fitted with a protective cap to prevent inadvertent firing. (6)The safety relief is a thermal expansion overpressure rupture disc. If bottle pressure is too high, the safety relief ruptures, allowing the bottle to discharge. The filler port is for introducing the extinguishing agent and pressurizing gas into the bottle. (7)The extinguishing agent is bromotrifluoromethane (halon), and the pressurizing gas dry nitrogen. The agent leaves no residue when discharged. B.APU Fire Switch (1)The APU fire switch is located on the APU fire control panel at pilot's aft control stand P8. When a fire is detected in the APU compartment, the APU fire switch handle red warning light comes on. A solenoid energizes releasing a mechanical interlock on the fire switch handle shaft. When the mechanical interlock is released, the fire switch handle can be operated by pulling the handle out and rotating it. Rotating the handle releases the extinguishing agent. After rotation, the fire handle automatically returns to an off-center position. To push the handle back in it must be in the center horizontal position. The fire switch handle can be manually unlocked by pressing the button behind the handle. (2) C.APU Shutdown Remote Control Panel (1)The APU shutdown remote control panel P62 is located on the nose landing gear. P62 contains a red APU FIRE LIGHT, APU Page 2 of 20

3 (2) D.Squib Test Panel SHT DN switch, and APU BTL DISCH switch. When a fire is detected in the APU compartment, the APU FIRE LIGHT comes on, and a warning horn sounds. Pressing APU SHT DN switch shuts down the APU and arms the remote APU bottle discharge. Pressing APU BTL DISCH switch, discharges the APU fire bottle. If APU SHT DN switch is pressed, the APU remote fire indication power must be recycled OFF and ON to reset the system, otherwise fire horn is disabled. (1)The squib test panel is located on the P61 right side panel. The switches on the panel are used to check extinguisher bottle squib cartridges. When pressed, the TEST switch on the panel checks continuity of the squib cartridges. A green test light comes on for a successful test. (2) (3)The squib test panel is located on the P61 right side panel. The switches on the panel are used to check extinguisher bottlesquib cartridges. When pressed, the TEST 1 switch on the panel check circuit continuity between the APU discharge switches and squib cartridges. A green test light comes on for a successful test. Page 3 of 20

4 Figure 1. APU Fire Extinguishing System - Component Location (Sheet 1) Page 4 of 20

5 FED ALL Page 5 of 20

6 Figure 1. APU Fire Extinguishing System - Component Location (Sheet 2) FED ALL Page 6 of 20

7 Figure 1. APU Fire Extinguishing System - Component Location (Sheet 3) FED , , 928, 930, , , , 989, Page 7 of 20

8 Figure 1. APU Fire Extinguishing System - Component Location (Sheet 4) FED 964, , Page 8 of 20

9 Figure 1. APU Fire Extinguishing System - Component Location (Sheet 5) FED , , 928, 930, , , , 989, Page 9 of 20

10 Figure 1. APU Fire Extinguishing System - Component Location (Sheet 6) FED 964, Page 10 of 20

11 Figure 1. APU Fire Extinguishing System - Component Location (Sheet 7) FED , , 928, 930, , , , 989, Page 11 of 20

12 Figure 1. APU Fire Extinguishing System - Component Location (Sheet 8) FED 964, Page 12 of 20

13 Figure 1. APU Fire Extinguishing System - Component Location (Sheet 9) FED ALL WITH HEX KEY PRESSURE SWITCH - KIDDE Page 13 of 20

14 Figure 1. APU Fire Extinguishing System - Component Location (Sheet 10) FED ALL WITH PTT PRESSURE SWITCH - HTL Page 14 of 20

15 3.Operation ( Ref. Figure 2) A. Functional Description (1) When a fire is detected in the APU compartment, the APU fire switch handle red warning light comes on and the fire warning bell sounds through the aural warning speakers. The red APU FIRE light on the P62 APU shutdown remote control panel also comes on. (2) After a fire is detected in the APU compartment, a solenoid energizes releasing a mechanical interlock on the fire switch handle shaft. The handle is then operable. The mechanical interlock is manually released by pressing the button located behind the fire handle. (3) When the airplane is on the ground and a fire is detected, the APU will shut down and the fire extinguisher bottle will discharge automatically. When the airplane is in flight and a fire is detected, the APU will shut down automatically but the extinguisher bottle must be discharged manually. (4) When the APU fire switch handle is pulled out, the APU automatically shuts down and the extinguishing bottle is armed. The following also happens: the APU generator field relay and generator circuit breaker are tripped; the APU fuel shut-off valve closes; the APU air supply valve closes; the fire bell shuts off; the external fire warning horn and APU fire light on P62 shut off. (5) Decreasing bottle pressure, by discharge or leakage, activates the bottle pressure switch. The following occurs when a decrease in pressure is detected: the APU BTL DISCH light on APU/CARGO fire control panel P8 comes on, and a APU BTL DISCH message appears on the EICAS display. (6) Page 15 of 20

16 (7) (8) Extinguishing occurs when the APU fire handle is pulled out and rotated in either direction. After rotation of the handle, an electrical signal is applied to the squib cartridge of the extinguisher bottle. The electrical signal detonates the bottle squib producing a rupture in the retaining disc allowing the extinguishing agent to be released. The extinguishing agent runs to an outlet nozzle at the bottom of the APU fire wall and is discharged into the APU compartment. (9) (10) Decreasing bottle pressure, by discharge or leakage, activates the bottle pressure switch. The following occurs when a decrease in pressure is detected: the APU BTL DISCH light on APU/CARGO fire control panel P8 comes on, and a APU BTL DISCH light message appears on the EICAS display. (11) B. APU Extinguishing System Test (1) Squib Test (a) The squib test control panel checks the integrity of extinguisher bottle squibs. Pressing the TEST switch sends a signal to the squib discharge cartridge. If the squib and circuit continuity are good, the green APU light on the panel will come on. (b) The squib test control panel checks the integrity of extinguisher bottle squibs. Pressing the TEST 2 switch sends a signal to the squib discharge cartridge. If the squib and circuit continuity are good, the green APU light on the panel will come on. (c) Page 16 of 20

17 C. DELETED D. Control (2) Pressure Switch Test (a) (b) Manually activating the bottle pressure switch tests discharge light circuit continuity. When the ground test pushbutton is pressed and held, the appropriate amber APU BTL DISCH light comes on and an APU BTL message appears on the EICAS display indicating a successful test. (c) Manually activating the bottle pressure switch tests discharge light circuit continuity. When the manual override test hex key is turned 1/4 turn clockwise, the appropriate amber APU BTL DISCH light comes on and an APU BTL DISCH message appears on the EICAS display indicating a successful test. (d) (1) To place the system in operation; provide electrical power (PAGEBLOCK /201, Electrical Power Control) (2) Make sure that these circuit breakers are closed: Main Power Distribution Panel, P6 Row Col Number Name G 1 C00780 FIRE EXT APU H 1 C00778 BTL 1 ENG L FIRE EXTINGUISHING Overhead Circuit Breaker Panel, P11 Page 17 of 20

18 Row Col Number Name FED 916 B 23 C00776 FIRE DETECTION APU 1 FED , , , 928, 930, , , , 964, B 24 C00776 FIRE DETECTION APU 1 FED 916 B 24 C00785 FIRE DETECTION APU 2 FED , , , 928, 930, , , , 964, B 25 C00785 FIRE DETECTION APU 2 FED ALL B 33 C00796 APU REMOTE FIRE IND Page 18 of 20

19 Figure 2. APU Fire Extinguishing Schematic (Sheet 1) FED 964, Page 19 of 20

20 Figure 2. APU Fire Extinguishing Schematic (Sheet 2) FED , , 928, 930, , , , 989, Page 20 of 20