Lights And Switches

Question 1

Fire switch pulled

Answer 1

1. Arms 1 discharge squib on each Eng fire extinguisher
2. Closes:
   a. wing fuel spar & Eng shut off valves
   b. Hydraulic s/o valve
   c. Eng bleed air valve (no wing A/I, No pack)
3. Disables thrust reversers for that engine
4. Trips generator control relay & breaker
5. Deactivates Eng driven hydraulic pump Low press light
6. Allows Eng Fire sw to rotate
7. Rotation of the Fire sw activates the squib which breaks the seal in the bottle & releases the fire ext. agent

Question 2

APU Fire switch pulled

Answer 2

1. Arms ext. bottle discharge squib
2. Closes:
   a. APU fuel s/o valve which shuts down the APU
   b. APU bleed air valve
   c. APU air inlet door
3. Trips the APU generator and relay off
   * Rotate either L/R to discharge. Red light on the APU fire sw extinguishes when the temp cools below the fire activation