Oxygen, Fire Protection and Emergency Equipment
Oxygen systems
Know the difference between a continuous-flow system (mask with rebreather bag, used in light aircraft) and a demand system (transport aircraft, with diluter-demand masks and a regulator). Oxygen is stored as high-pressure gas (typically 1,800-2,000 psi in light aircraft cylinders), as liquid oxygen, or generated by a chemical or molecular sieve system. Traps: assuming oxygen is available at any altitude without checking quantity and pressure; forgetting that oxygen is a fire hazard and that grease must never contact fittings.
Fire detection and protection
Detection uses heat, smoke or rate-of-rise sensors, with engine fire loops (continuous loop or spot detectors) and cargo smoke detectors. Protection uses fire bottles (Halon or equivalent) discharged into the engine nacelle or cargo compartment, with a two-shot system on many transports. Know the indications: fire warning, bottle discharge, and the difference between a fire warning and an overheat warning.
Emergency equipment
Life jackets, rafts, slides, ELT, first aid kits, flashlights and portable breathing equipment. Traps: assuming an ELT activates automatically on all aircraft (it may be manual); and forgetting that a fire bottle is a one-shot discharge.
Worked example: an engine fire warning illuminates after take-off. Reasoning: confirm the warning, reduce power, discharge the bottle, and if the warning persists, land as soon as possible. The rule is: fire warning is treated as real until proven otherwise.