Supplied B1 Module 07A textbook: PDF pages 23–36.
Electrical hazards and isolation
Electrical injury depends on the current path, duration and conditions of contact, as well as voltage. Wet skin and metal jewellery can increase risk. Before maintenance, identify every supply, isolate it using the approved procedure, prevent inadvertent reconnection and verify the required safe state. Batteries, capacitors and externally powered circuits may retain energy after a switch is turned off. Do not use a continuity meter to prove that a circuit is de-energised. Damaged cords, overheated connections and incorrect protection can cause fires as well as shocks.
Why can equipment remain hazardous after its main switch is turned off? Stored energy or another power source may remain.
Compressed gases
A cylinder is both a pressure vessel and a heavy object. Secure it against falling, protect its valve during transport and identify its contents by the approved marking rather than colour alone. Use the correct regulator and hoses; inspect them before connecting. Open valves as the equipment procedure specifies and keep personnel clear of pressure jets. Never use compressed gas to clean clothing or skin. A leak can displace breathable air even when the gas itself is not poisonous.
What is the main purpose of securing a gas cylinder? Prevent falling and damage to its valve.
Oxygen cleanliness
Oxygen supports combustion; it is not a fuel. A material that burns slowly in air may burn violently in an oxygen-rich environment. Oil and grease on oxygen equipment are particularly dangerous. Keep hands, tools, fittings and approved servicing equipment clean and use only oxygen-compatible materials. Keep ignition sources away, ventilate the area and follow the specified connection and valve-opening procedure. Do not interchange oxygen equipment with equipment used for other gases merely because the fittings can be connected.
Why must oil and grease be excluded from oxygen equipment? They can ignite violently in oxygen-rich conditions.
Oils, solvents and chemicals
Read the safety data sheet before choosing gloves, eye protection, ventilation and spill response. A glove suitable for one solvent may be unsuitable for another. Store chemicals in labelled compatible containers, separate incompatible substances and keep lids closed. Clean spills promptly using the specified method. Avoid breathing vapour and prevent skin contact; fire and health hazards may coexist. Chemical waste requires controlled disposal. An unlabelled container is not an invitation to identify its contents by smell.
Which document guides chemical handling and protective-equipment selection? The safety data sheet.
Fire recognition and response
A fire needs fuel, heat and oxygen; interrupting one can stop combustion. Raise the alarm, protect an escape route and use an appropriate agent only when trained and it is safe to do so. Fire-class letters differ between classification systems: in the US, class C denotes energised electrical equipment; European class C denotes gases. Water is unsuitable for energised electrical equipment and can spread burning liquid. Metal fires need an approved metal-fire agent. Carbon dioxide displaces oxygen and can create an asphyxiation hazard in confined spaces.
What must be checked before choosing an extinguisher by its class letter? The applicable classification system and actual hazard.
Workshop and flight-line safety
Keep walkways, escape routes and emergency equipment unobstructed. Use guards and eye protection with machinery, restrain loose clothing and secure the work. On the flight line, maintain engine inlet, exhaust and propeller exclusion zones. Treat a propeller as capable of moving unexpectedly. Helicopter rotor clearance changes with wind and rotor movement; approach only as directed by the crew. Hearing protection, communication and foreign-object control are part of the same safety system. Stop the task if a hazard cannot be controlled.
What is the purpose of a foreign-object check before an engine run? Remove loose items that could be ingested or cause damage.
Apply the knowledge
Work through these examples before starting the quiz. Explain why the other choices would not meet the requirement.
A colleague is receiving an electric shock. What should be addressed before touching them?
Isolate the source or use an approved safe rescue method — A rescuer must not become part of the electrical circuit.
An oxygen servicing connector has oily contamination. What is the correct action?
Stop and have it cleaned or replaced by the approved procedure — Oxygen equipment needs controlled cleanliness and compatible cleaning methods.
A solvent container has lost its label. What should the technician do?
Quarantine it and establish its identity through the approved process — Unknown chemicals cannot be handled safely by guesswork.
Smoke is developing near an electrical supply. What is the first priority?
Raise the alarm and make the area safe according to the emergency procedure — Alarm, evacuation and isolation take priority over equipment recovery.