What is the reason for most false fire detection?

What is the reason for most false fire detection?

• A. The following troubleshooting procedures represent the most common difficulties encountered in engine fire detection systems. (1) Intermittent alarms are most often caused by an intermittent short in the detector system wiring. Such shorts may be caused by a loose wire which occasionally touches a nearby terminal, a frayed wire brushing against a structure, or a sensing element rubbing long enough against a structural member to wear through the insulation. Intermittent faults can often best be located by moving wires to recreate the short.
• B. Loose wiring
• C. Sensor wear
• D. Humidity

Answer: (A)

Intermittent electrical faults in the fire-detection circuitry are the most common cause of false alarms. The detector loop relies on stable wiring and contacts; when a wire is loose, frayed, or chafes against a structure, it can intermittently short or make contact, creating a transient condition that the system interprets as a fire condition. Because these faults can come and go as the aircraft vibrates or moves wiring, alarms appear sporadic, even though no fire is present. Maintenance troubleshooting targets reproducing the fault by manipulating wiring to locate the short and inspecting insulation, terminations, and routing to prevent contact. Other issues like humidity or sensor wear can cause problems, but intermittent wiring faults are the typical source of nuisance false detections.

Intermittent electrical faults in the fire-detection circuitry are the most common cause of false alarms. The detector loop relies on stable wiring and contacts; when a wire is loose, frayed, or chafes against a structure, it can intermittently short or make contact, creating a transient condition that the system interprets as a fire condition. Because these faults can come and go as the aircraft vibrates or moves wiring, alarms appear sporadic, even though no fire is present. Maintenance troubleshooting targets reproducing the fault by manipulating wiring to locate the short and inspecting insulation, terminations, and routing to prevent contact. Other issues like humidity or sensor wear can cause problems, but intermittent wiring faults are the typical source of nuisance false detections.