Airframe Fire Protection Systems practice questions

Answer: C) Fire detection and built-in suppression

• AIncorrect. That describes Class B.
• BIncorrect. Class C requires detection.
• CCorrect. Crews cannot reach it, so it has built-in suppression.
• DIncorrect. Cargo compartments carry cargo.

Answer: A) It floods the closed compartment with Halon 1301, then a metered discharge keeps up an agent concentration for the rest of the flight

A Class C cargo compartment has a cockpit-controlled built-in system that floods the closed compartment with agent (typically Halon 1301) and keeps up a suppressing concentration, with ventilation controlled so the agent stays effective.

• ACorrect. Class C systems are controlled from the cockpit. They rapidly flood the compartment with agent to knock the fire down, then hold a suppressing concentration (often with a metered discharge) until landing.
• BIncorrect. 14 CFR 25.857(c) requires means to control ventilation and drafts so the agent can control the fire. More airflow would dilute the agent and feed the fire.
• CIncorrect. Class C systems use an approved gaseous agent such as Halon 1301, not the potable water system.
• DIncorrect. Bleed air contains oxygen and is hot. It would not suppress a fire, and it is not used as an extinguishing agent.

Answer: B) Free of kinks and chafing

• AIncorrect. Sharp bends damage it.
• BCorrect. Kinks, dents or chafing can cause false warnings or failures.
• CIncorrect. It is clamped as specified.
• DIncorrect. It must be supported.

Answer: B) A second bottle can be fired into the same engine

• AIncorrect. It allows two discharges to one area.
• BCorrect. It provides a second chance at extinguishing.
• CIncorrect. Each bottle discharges once.
• DIncorrect. It is about extinguishing.

Answer: A) A means for the crew to check, in flight, the functioning of each detector electric circuit

14 CFR 25.1203(d) requires a means for the crew to check, in flight, the functioning of each fire or overheat detector circuit, normally done with a flight deck test switch.

• ACorrect. Section 25.1203(d) requires this, normally a flight deck test switch that checks loop continuity and the warning circuits.
• BIncorrect. Discharging a bottle would empty it and leave the zone unprotected. Detection is verified electrically, not by discharging agent.
• CIncorrect. Detector elements are inspected and tested during scheduled maintenance. The regulation requires a built-in way for the crew to check circuit function.
• DIncorrect. Applying heat to an element is a maintenance check, not an in-flight crew check. The required in-flight check is done electrically.

Answer: C) Heat expands gas in a tube, closing a pressure switch

• AIncorrect. Thermocouple systems are different.
• BIncorrect. Smoke detectors do that.
• CCorrect. This sensor responds to average and local heat.
• DIncorrect. It senses heat.

Answer: A) Pressure gauge or weight, safety pin and tamper seal, secure mounting, and inspection or test dates

A routine extinguisher inspection is a visual check that the extinguisher is in place, charged and ready. The technician checks the gauge or weight, the pin and tamper seal, the mounting, and the inspection or test dates.

• ACorrect. These items confirm that the extinguisher is in place, charged, not tampered with, and within its inspection and test intervals, so it is ready for use.
• BIncorrect. Discharging even a small amount partly empties the extinguisher and means it must be serviced. An inspection is a visual check, not a test discharge.
• CIncorrect. Taking the valve apart is maintenance work done by qualified people. A routine inspection checks the charge with the gauge or by weight.
• DIncorrect. The placard and color do not show whether the extinguisher is ready. Its charge, seal, mounting and dates must be checked at each inspection.

Answer: A) A narrow infrared waveband centered near 4.3 micrometers, typical of hydrocarbon flames

Optical (flame) detectors sense specific radiation from hydrocarbon flames. IR types use a filter that passes a narrow band centered near 4.3 micrometers.

• ACorrect. FAA material says a filter passes only a tight IR band centered around 4.3 micrometers to the sensing surface. This band is typical of hydrocarbon flame emissions.
• BIncorrect. Visible light comes from many sources, such as sunlight and lighting, so it would cause false alarms. IR detectors are filtered to a specific infrared band.
• CIncorrect. That describes an ultraviolet-type optical detector, not the infrared type in this nacelle.
• DIncorrect. The detector is filtered to a narrow band so it responds to flame emissions rather than to general heat from hot engine parts.

Answer: B) The bottle was discharged normally by the crew

• AIncorrect. That is shown by the red disc.
• BCorrect. A yellow disc blows out on normal discharge.
• CIncorrect. A missing disc means discharge occurred.
• DIncorrect. It indicates discharge.

Answer: C) The engine accessory section

Section 14 CFR 25.1181 lists engine power and accessory sections, APU compartments, fuel-burning heaters, and turbine engine sections as designated fire zones. Each must meet the fire protection requirements, including detection and extinguishing.

• AIncorrect. Class C compartments must have detection and a built-in extinguishing system, but they are covered by the cargo compartment rules. They are not on the 25.1181 list of designated fire zones.
• BIncorrect. Wheel wells may be monitored for overheat on some airplanes, but 25.1181 does not list them as designated fire zones.
• CCorrect. Section 25.1181(a) lists the engine accessory section as a designated fire zone, along with the power section, APU compartments, fuel-burning heaters, and turbine engine compressor/accessory and combustor/turbine/tailpipe sections.
• DIncorrect. The electronics bay contains electrical equipment, but 25.1181 does not list it as a designated fire zone.