Why is fire the greatest hazard to aircraft safety?
It causes rapid structural damage, loss of critical systems, and potential fuel ignition.
What fire protection systems are required on multi-engine turbine aircraft?
Fixed fire detection systems and fixed fire extinguishing systems.
What is a fire zone?
An area where fire is likely to occur or would have severe consequences and contains ignition sources and flammable fluids.
What are the main requirements of a fire zone?
Detection, extinguishing capability, fire-resistant construction, and sealing.
Examples of typical fire zones
Engine sections, APU compartments, combustion equipment, turbine areas with flammable fluids.
Main causes of engine fires
Abnormal temperatures, flammable fluid leakage, and component failure.
Two categories of engine fire causes
Thermodynamic failures and mechanical failures.
What is thermodynamic turbine failure?
Failure caused by loss of cooling airflow controlling turbine temperature.
Why are turbine blades vulnerable to overheating?
They operate near material limits and rely on internal cooling and correct fuel-air ratio.
Causes of thermodynamic turbine failure
Ice accumulation, bleed air extraction, air leakage, over-fuelling, compressor stall or surge.
Effects of thermodynamic turbine failure
Blade melting, distortion, separation, and high-energy debris.
Consequences of thermodynamic turbine failure
Casing penetration, tail cone severance, and fire ignition.
What causes mechanical turbine failure?
Physical damage, fatigue, overspeed, or material stress.
Typical mechanical turbine failures
Blade fracture and disc failure.
Hazards of mechanical turbine failure
Turbine case penetration and damage to fuel, oil, or hydraulic lines.
Main components of a fire protection system
Detection, extinguishing, cockpit indication, and system testing.
Key performance requirement of fire detection systems
Early reliable detection with minimal false warnings.
Why must each engine have a separate fire detection system?
To ensure independent and reliable fire protection.
Two main types of fire detection systems
Spot detection systems and continuous loop systems.
Where are spot detector systems typically used?
Older aircraft, light aircraft, and helicopters.
Types of spot fire detectors
Thermal switch, thermocouple, optical, pneumatic thermal.
How does a thermal switch fire detector work?
A switch closes at a preset temperature to trigger a warning.
Advantages of thermal switch systems
Simple, reliable, and low cost.
Limitations of thermal switch systems
Cannot detect slow overheating or rate of temperature rise.
