What does a continuous loop detector system consist of?

• A. Continuous loop tubing installed in areas susceptible to high temperatures, such as engine, APU, bleed air ducts, and air conditioning pack compartments
• B. Smoke detectors in cargo holds
• C. Infrared sensors on engine nacelles
• D. Fire extinguishers in bays

Answer: (A)

Continuous loop detector systems use a loop-shaped sensing element installed around areas prone to heat and fire, such as engine compartments, the APU, bleed air ducts, and air conditioning pack spaces. This loop forms a closed circuit that monitors changes in its electrical characteristics as it is heated. When a fire starts and heat elevates the loop, the detected change triggers the fire-warning system, giving early, wide-area coverage in confined, hard-to-reach spaces. This approach is specific to distributed heat sensing in high-risk zones, rather than relying on smoke detectors, infrared sensors, or extinguishers.