Which class includes a separate approved detector system, built-in extinguishing or suppression system, and requires control ventilation to prevent hazardous quantities entering compartments?

• A. Class A
• B. Class B
• C. Class D
• D. Class C

Answer: (D)

Fire safety in contained storage spaces is defined by a combination of detection, suppression, and ventilation control. This class is the one that requires a separate approved detector system to spot a fire inside the compartment quickly, a built-in extinguishing or suppression system to act automatically and contain or suppress the fire, and controlled ventilation to prevent hazardous quantities—such as smoke, toxic gases, or flammable vapors—from entering other compartments or occupied areas. The idea behind these requirements is to ensure rapid detection and automatic response within a high‑risk space, while also preventing the spread of dangerous substances through the aircraft’s ventilation system. This combination of independent detection, integrated suppression, and ventilation control distinguishes it from other classes that don’t mandate all these specific provisions.