Fire Detection and Suppression Systems

Overview of Fire Detection and Extinguishing Systems

• Call for Attention to Fire Detection Systems
  • Call on the CCAS (Centralized Crew Alerting System).
  • Address faults in the system; a faulted system will not provide fire detection.
  • Important to document actions in the voice recorder.

Understanding of Fire Detection Procedures

• If you have a faulted fire detection loop, turn it off.

• Always consult the Quick Reference Handbook (QRH), regardless of how simple the issue seems.

  • MEL (Minimum Equipment List) for Fire Detection

• It is permissible for one loop on each engine to be inoperative if the effective loops are selected.

• Attempts to remove MEL requirements have been unsuccessful due to false fire indications.

Case Study of Fire Loop Failures

• An incident occurred where a false fire indication caused an engine to be pulled and thoroughly inspected.
• Shock cooling in the hot section of the engine was a concern due to the faulty loop.
• Involves usage of fire bottles and procedures that must be followed even in cases of no actual fire.

Electrical Considerations for Fire Detection Systems

• Power Requirements
  • Fire detection systems require basic battery power or other power sources to operate correctly.
  • Systems are wired for redundancy:
  • One off the emergency bus and one off the essential bus.

-Battery Power and Fire Detection

• If the battery is dead, fire detection systems will not function.

Fire Detection Systems and Failures

• Consequences of Fire Loop Failures
  • A single fault in the detection system can fail to detect fires while a loop is operational.
  • If both loops A and B fail, fire detection is completely compromised.
  • In such cases, no fire detection is provided; proceed with caution until safely on the ground.

Fire Extinguishing Systems

• Location and Operation of Fire Bottles

  • Fire bottles are located at the wing root of the aircraft, where the wing attaches to the fuselage.
  • Each engine has two fire bottles:
  • Agent one corresponds to its associated engine, while agent two comes from the opposite side.
  • Discharge indications depend on pressure readings of the fire bottles rather than visual blowout discs.

• Discharge Light Explanation

  • A discharge light may indicate low pressure from intentional or thermal discharge.

Indications of Engine Fire

• Recognizing Fire Detection Signals

  • Illumination of the fire handle, master warning, and continuous chimes indicate a fire.
  • Fire indicators show directly on the CCAS.

• Fire Handle Mechanism

  • Pulling the fire handle initiates multiple actions, including fuel shut-off from both low and high-pressure systems.
  • The conditions under which the lights turn off and actions correlate with effective control of an engine fire are detailed.

Memory Items for Fire Management

• Emergency Actions
  • Memory item sequence should include:
  • Flight idle, conditional air feather, fuel shutoff, and activation of the affected engine’s fire handle.
  • Continuous monitoring is necessary to ensure the fire management systems are active until the fire is confirmed extinguished.

Operational Challenges and Real-World Scenario

• Situational Awareness
  • A scenario illustrates a maintenance problem resulting in a potential fire from a fuel leak after shutdown.
  • Although power is lost, the fire handle can still be pulled to activate fire suppression systems.

Summary of Fire Extinguishing Capability Without Power

• Electrical Limitations vs Capability
  • There can be no fire detection when the aircraft is powered down, but fire suppression can still be activated.
  • Each fire bottle contains 6.5 pounds of halon.

Engagement and Training

• Continuous Learning and Drills
  • Importance of familiarity with equipment and emergency procedures through repeated training.
  • Engage with colleagues to enhance memory and response efficiency in potential emergency scenarios.

Conclusion

• Final Remarks

  • Encourage ongoing discussion and learning from operational experiences.
  • Prepare for upcoming training sessions and stay engaged.

• Instructor wraps up session with humor and lightheartedness signaling the end of the training for the day.