Fire Detection

Question 1

Detectors

Answer 1

5 digital sensors (2 each eng, 1 APU)

• -3 on firewalls
• -2 (eng only) deck mounted

Trigger T-Handle when detect infrared radiation and no blue light (sunlight)

Sunlight filtered through smoke or haze or at sunrise/sunset may trigger detectors

Question 2

Extinguishers

Answer 2

Provide two-shot capability (main and reserve) to either engine compartment or APU compartment

2 bottles filled with halon, charged by nitrogen

Question 3

Engine T-Handle Operation

Answer 3

Engine handle pulled aft arms the system and mechanically places the fuel selector in the OFF position

Logic module determines which CADS to fire and into which compartment

When both #1 and APU handles pulled, extinguishes last compartment pulled

If #2 pulled, always aims that compartment

Question 4

APU T-Handle

Answer 4

Removes electrical power from the APU airframe fuel shutoff valve, allowing it to close

Also removes electrical power from the prime boost pump, sends a stop signal to the ESU/DESU, arms fire extinguisher system and positions valve to APU compartment

Question 5

Notes

Answer 5

• If No 2 DC PRI bus not energized (no ac power), the RESERVE position must be used to discharge the agent into the APU or No 1 engine compartment (No 2 will have no extinguisher capability without ac power)
• When ac power is available, activation of multiple T-handles may result in both bottles being fired at the same time, leaving no reserve capability

Question 6

Impact Operation

Answer 6

10g sensor mounted to airframe activated via power from BATT UTIL bus, discharging one bottle to each engine compartment