ATR systems - Fire protection

What Are the Risks of Aircraft Operations?

Introduction to Fire Protection Systems in ATR Aircraft

• The worst-case scenario for an aircraft is identified as a fire inside the aircraft, despite other serious issues like landing gear failure or engine failure.

• Captain Magna Noodle introduces himself and outlines that this video will cover fire protection systems in all ATR aircraft variants, from 42-300 to 72-600.

• This video serves as a supplementary resource and does not replace formal training; viewers are encouraged to report any errors.

Causes and Detection of Engine Fires

• An engine fire can result from oil leaks or improperly installed fuel nozzles leading to fuel leaks, which can occur shortly after takeoff.

• The engine fire detection system uses sensing cables (loops A and B), made of Inconel, which detect temperature changes indicative of a fire.

• When temperatures exceed 258 degrees Celsius, an ancient fire warning is triggered through electrical resistance changes in the loops.

Fire Suppression Mechanisms

• Each engine has two bottles filled with extinguishing agent; one bottle corresponds to each engine side. Activation occurs by pulling the fire handle.

• The extinguishing agent is released via a small explosive charge called a squib when the agent push button is pressed.

Handling Smoke on Board

• Smoke onboard presents significant danger; it includes visible smoke and toxic fumes. Immediate actions include donning oxygen masks set to 100% oxygen.

• Communication protocols during smoke events involve isolating microphones and using interphone systems due to loud noise levels when wearing masks.

Emergency Procedures During Smoke Events

• If smoke or fumes are detected in the cockpit, pilots should switch off recirculation fans to prevent spreading smoke throughout the cabin.

Smoke Detection and Fire Management in Aircraft

Overview of Smoke Detection Systems

• The forward cargo compartment is equipped with a photoelectric smoke detector, effective for detecting smoke from smoldering fires, crucial for safety in cargo areas.

• An alert is triggered when smoke is detected by the ceiling-mounted smoke detector in the forward cargo compartment. The fan's operation can be heard nearby.

Emergency Procedures Upon Smoke Detection

• After detecting smoke, the procedure involves notifying cabin crew to extinguish the fire while selecting avionics vent exhaust mode to allow smoke escape through an overboard valve. This prevents spread to the cabin area.

• In cargo configurations without cabin crew, it’s critical not to suppress fire by reducing cabin pressure as this dilutes oxygen content at the rear of the aircraft.

Additional Smoke Detectors and Alerts

• Two additional smoke detectors are located in the aft cargo compartment and lavatory; alerts are triggered upon detection but specific information about which sensor activated is only available to cabin crew.

• Cargo versions have four extra ceiling-mounted smoke detectors linked to both forward and aft alerts, enhancing safety measures during flight operations.

Firefighting Equipment and Crew Training

• Depending on ATR variant regulations, there may be two or three handheld fire extinguishers available; one contains water while others contain halon gas for effective firefighting. Cabin crew receive regular training on handling fires in both cabins and cargo compartments.

• A halon extinguisher can be inserted into an orifice above the aft cabinet tenant seat, allowing for targeted application of fire suppression agents within deep cargo areas.

Automatic Fire Extinguishing Systems

• An automatic fire extinguisher located above waste bins activates when temperatures exceed 77 degrees Celsius; this system is referred to as avionics smoke detection in operational manuals despite older terminology referring to it as electrical smoke detection.

• Ionization smoke detectors function similarly to household models using americium 241; they detect changes in electrical current caused by ion disruption from incoming smoke particles, triggering alarms accordingly.

Managing Electrical Fires and Emergency Landings

• In case of electrical fires indicated by alarms due to evacuated smoke or air conditioning issues, pilots must identify sources of smoke before deciding on emergency landing procedures if control cannot be maintained over aircraft systems.

• It’s essential for crews to differentiate between various types of alarms (e.g., electrical vs air conditioning) based on initial conditions leading up to alarm activation; confusion could complicate response efforts during emergencies.

Testing Smoke Detectors Before Flights

Air Conditioning Smoke in Aircraft: Identification and Procedures

Common Sources of Smoke Onboard

• The primary source of smoke on aircraft is the air conditioning system, except for the Boeing 787. Air from engine compressors can carry oil vapor into the air conditioning system if there’s an oil leak.

Understanding Air Conditioning Systems

• In Asia aircraft, the left air conditioning system supplies both cockpit and cabin, while the right only serves the cabin. If smoke is reported in the cabin but not in the cockpit, it indicates a potential fault in the right air conditioning pack.

Emergency Procedures for Smoke

• The emergency checklist notes that smoke may originate from air conditioning systems. Confirmed air conditioning smoke requires following specific procedures distinct from other smoke sources.

• Initial steps include switching off one air conditioning pack; if ineffective, switch it back on and turn off the other pack. Caution is advised as this may trigger electrical smoke.

Identifying Air Conditioning Smoke

• Air conditioning smoke typically emanates from vents and can be nearly invisible or thick. It has a distinct burnt oil smell due to its origin from engine oil vaporization.