FAA Powerplant Written Practice Test

How can one determine if a false alarm in a continuous loop fire detection system is caused by the control unit or the sensing loop?

1. By replacing the control unit

2. By disconnecting the loop from the control box and observing if the false alarm stops

3. By resetting the control unit

4. By checking the battery voltage of the control box

The correct answer is: By disconnecting the loop from the control box and observing if the false alarm stops

To determine if a false alarm in a continuous loop fire detection system is due to the control unit or the sensing loop, disconnecting the loop from the control box is the most effective method. This approach allows you to isolate and evaluate the components of the system. When the sensing loop is disconnected, if the false alarm ceases, it indicates that the issue lies within the loop itself, such as a malfunctioning sensor or a fault in the wiring. Conversely, if the false alarm continues even after disconnecting the loop, it suggests that the problem resides in the control unit. This method is straightforward and provides clear diagnostic insight without unnecessary component replacements or resets, which may not pinpoint the origin of the problem. By following this procedure, a technician can effectively troubleshoot the system, ensuring that the root cause of the false alarm is accurately identified and addressed.