Engine Fire Protection Systems practice questions

Answer: A) With close-fitting fireproof grommets, bushings, or bulkhead fittings

Firewall penetrations must be sealed with close-fitting fireproof grommets, bushings, or firewall fittings so the firewall stays fireproof and sealed against flame and fluids.

• ACorrect. Each firewall opening must be sealed with close-fitting fireproof grommets, bushings, or firewall fittings so that flame and hazardous fluids can't get through.
• BIncorrect. Rubber grommets and aluminum alloy are not fireproof. They would fail in a fire and open a path through the firewall.
• CIncorrect. Firewall seals have to be fireproof, not just fire-resistant, and they must fit closely. A deliberate gap would let flame and fluids through.
• DIncorrect. A sealant bead is not one of the fireproof grommets, bushings, or fittings required for firewall openings, and it can't be relied on to stop flame.

Answer: A) Prevent fuel, oil, or other flammable fluid leaking from a failed component from collecting in the zone

Fire-zone drains keep leaked flammable fluids from collecting where they could feed a fire. Ventilation is the separate requirement that prevents flammable vapors from building up.

• ACorrect. 14 CFR 25.1187 requires complete drainage to minimize the hazards from failure or malfunction of any component containing flammable fluids, so leaked fluid cannot collect and feed a fire.
• BIncorrect. Preventing flammable vapor accumulation is the purpose of fire-zone ventilation, which 25.1187 addresses separately from drainage.
• CIncorrect. Drains are not pressure-relief devices for agent discharge. The agent is meant to stay in the zone at a set concentration to put out the fire.
• DIncorrect. Moisture can affect detector loops, but the regulatory purpose of fire-zone drainage is to remove leaked flammable fluids, not to protect the detection system.

Answer: B) The service life calculated from the date stamped on the cartridge

Discharge cartridges (squibs) have a limited service life based on the manufacturer's date stamp, so their dates are checked and expired cartridges are replaced.

• AIncorrect. The pressure reading checks the agent charge in the container. It says nothing about how long the cartridge has been in service.
• BCorrect. Squibs have a limited service life, calculated from the manufacturer's date stamp on the cartridge. They are replaced when that life expires, even if never fired.
• CIncorrect. A weight check confirms the agent quantity in some containers. It does not decide whether the cartridge has expired.
• DIncorrect. The red disc shows that the container discharged overboard because of overheat or overpressure. It does not track cartridge service life.

Answer: A) To keep flammable fluid from flowing into the engine fire zone, where it would feed a nacelle fire

The firewall fuel valve isolates the engine fire zone from the fuel supply so a nacelle fire is not fed. It is closed by the fire handle and must not cut off fuel to the other engines.

• ACorrect. 14 CFR 25.1189 requires a way to shut off or prevent hazardous quantities of fuel, oil, and other flammable fluids from flowing into a designated fire zone. The firewall valve does this for fuel.
• BIncorrect. Preventing reverse flow is the job of a check valve, not the firewall valve.
• CIncorrect. That is a crossfeed valve. 25.1189 actually requires that closing a fuel shutoff valve must not make fuel unavailable to the other engines.
• DIncorrect. Fuel pressure is controlled by pumps, regulators, and relief valves. The firewall valve is either open or closed for isolation and does not regulate pressure.

Answer: B) It flows through dedicated discharge lines ending in perforated tubing or spray nozzles in the zone

A fixed engine fire-extinguishing system has its own discharge lines. They end in perforated tubing or nozzles that spread the agent through each protected nacelle zone.

• AIncorrect. The agent is not sent through the engine gas path. It must reach the nacelle fire zones around the engine, where flammable-fluid fires occur.
• BCorrect. The agent leaves the container through its own discharge plumbing. Perforated distribution tubing or discharge nozzles then spread it through the fire zone.
• CIncorrect. Ventilation airflow dilutes the agent and does not distribute it. The system is designed to reach the required concentration despite that airflow, using its own plumbing.
• DIncorrect. Continuous-loop detector elements are sensors only. They are not connected to the extinguisher container and carry no agent.

Answer: A) The compressor and accessory sections of the turbine engine

14 CFR 25.1181 lists the designated fire zones, including the engine power and accessory sections, the compressor and accessory sections of turbine engines, and APU compartments. Inlet ducts, wheel wells and cargo compartments are not on that list.

• ACorrect. Section 25.1181(a) lists the compressor and accessory sections of turbine engines as designated fire zones. These areas have flammable fluid lines and ignition sources, so they need fire detection and extinguishing coverage.
• BIncorrect. The inlet duct is part of the engine installation but is not listed in 25.1181 as a designated fire zone. It does not normally contain flammable fluid components.
• CIncorrect. Wheel wells can get hot from brakes, but they are not among the regions 25.1181 lists as designated fire zones.
• DIncorrect. Cargo compartments have their own fire protection rules based on compartment class. They are not powerplant designated fire zones under 25.1181.

Answer: B) Heated gas raises pressure

• AIncorrect. That is a smoke detector.
• BCorrect. Heating releases or expands gas, closing a pressure switch.
• CIncorrect. This is not how it works.
• DIncorrect. This is unrelated.

Answer: A) Fuel, hydraulic supply, and bleed air to that engine are shut off, its generator is tripped off line, and that engine's extinguisher discharge circuit is armed

An engine fire handle isolates only its own engine by shutting off fuel, hydraulics, bleed air and the generator, and it arms that engine's extinguisher. A separate crew action then discharges the agent.

• ACorrect. Pulling the handle isolates the affected engine from aircraft systems (fuel, hydraulics, bleed air, electrical) and arms the extinguisher. The crew then discharges the agent with a separate action, such as turning the handle or pressing a discharge button.
• BIncorrect. On most installations, pulling the handle only arms the discharge circuit. Releasing the agent takes a second, deliberate action, such as turning the handle, so the agent is not used up when it isn't needed.
• CIncorrect. Each handle isolates only its own engine. The shutoff means must be arranged so that shutting off one engine's fuel does not cut fuel to the remaining engines.
• DIncorrect. Detector loops are checked with a separate fire test switch. Pulling the handle also silences the warning, but its main job is to isolate the engine and arm the extinguisher.

Answer: A) Dents, kinks, chafing, loose fittings or obstructions that could restrict agent flow

Discharge lines are inspected for physical damage, security and blockage, because any restriction keeps the agent from reaching the fire zone. Pressure, squib and hydrostatic checks belong to the container and discharge valve.

• ACorrect. The discharge lines must be undamaged, secure and clear so that the agent reaches the protected zone at the required concentration and rate.
• BIncorrect. This is a check of the extinguishing agent container (bottle) charge, not of the discharge lines.
• CIncorrect. This is a check of the discharge valve's electrical firing circuit, not of the lines that carry the agent.
• DIncorrect. Hydrostatic test dates apply to the pressure containers. Discharge lines are inspected for physical condition and security.

Answer: C) Automatic APU shutdown

• AIncorrect. Ground APU fires are handled automatically.
• BIncorrect. That would worsen the fire.
• CCorrect. Some systems also discharge the bottle automatically.
• DIncorrect. Fuel is shut off.