What are the engine/APU/EPU fire control steps?

• A. Use fire protection/shutdown bottles, direct agent into intake/compartment, open cowling carefully, and use piercing nozzle only as last resort.
• B. Open cowling first, then spray water inside; never shut down the engines.
• C. Direct agent into exterior surfaces only; avoid the intake.
• D. Do not use any safety devices; rely on crew.

Answer: (A)

When fighting an engine, APU, or EPU fire, the priority is to quickly shut down the affected unit and flood the engine bay with extinguishing agent to cool and smother the fire. The onboard fire protection/shutdown bottles are used to both interrupt the fuel source and release extinguishing agent into the nacelle where the fire is burning, helping to suppress flames fast.

Directing the agent into the intake and into the engine compartment is essential because the fire lives inside the nacelle where hot metal, fuel, and vapor are concentrated. Spraying into the intake and the surrounding compartments ensures the agent reaches the flame zone and cools hot surfaces, reducing the chance of reignition.

Opening the cowling, done carefully, provides access to the engine bay for better application of agent and for inspection, but it must be done with awareness of heat, fuel leaks, and the risk of exposing crew to hazards. This step supports effective control without compromising safety.

Using a piercing nozzle is reserved for situations where a direct application through a port is needed to reach the core of the engine fire. It should be employed only as a last resort because it is more invasive and requires careful handling to prevent unintended effects or damage.

Water is not used on petroleum-based engine fires, and directing agent only to exterior surfaces misses the fire inside the nacelle. Relying on no safety devices is unsafe—the onboard fire suppression system and proper shutdown sequences are designed to control these fires quickly and safely.