Which switch must be depressed to activate the engine fire extinguishing system?

• A. BOT1/BOT2 Switch Depressed
• B. Fire Warning On
• C. Emer Off Switch Released
• D. N1 RPM Less Than 50%

Answer: (A)

Activating an engine fire extinguishing system is a deliberate, manual action. The extinguishing agent is released only when you depress the switch that controls the extinguishing bottles for the engines. On a dual-bottle system, pressing the BOT1/BOT2 switch specifically initiates the discharge into the selected engine(s), ensuring the agent is delivered where the fire is suspected.

Other options don’t trigger discharge: a fire warning on merely signals a fire without releasing agent; the Emer Off switch is used to shut down and isolate the engine’s systems but does not automatically discharge the extinguishing bottles; and an engine parameter like N1 RPM below a threshold is just a condition, not a control to deploy extinguishing agent.