Special Precautions When Working on a Gaseous Oxygen System

TASK 35-00-00-860-001-A
Special Precautions When Working on a Gaseous Oxygen System

WARNING: OBEY THESE SPECIAL PRECAUTIONS WHEN YOU DO THIS PROCEDURE:

CAREFULLY OBEY THE REPLENISHING INSTRUCTIONS. IF YOU DO NOT OBEY THESE INSTRUCTIONS, YOU CAN CAUSE A FIRE OR AN EXPLOSION.
PREVENT ALL MAINTENANCE PROCEDURES NEARER THAN 5 M (16.4 FT) TO THE WORKING AREA OF THE AIRCRAFT.
STOP ALL REFUELING, ALL REPAIRS ON FUEL AND HYDRAULIC SYSTEMS, AND ALL PROCEDURES THAT USE FLAMMABLE MATERIALS SUCH AS CLEANING AND DE-ICING MATERIALS.
PUT A WARNING NOTICE IN THE COCKPIT, THE WORK AREA AND THE CABIN TO TELL PERSONS NOT TO OPERATE ELECTRICAL SWITCHES DURING THE OXYGEN FILLING PROCEDURE.
TELL ALL PERSONS IN THE AIRCRAFT THAT THE OXYGEN FILLING PROCEDURE IS IN PROGRESS.
IF YOU THINK THAT A THUNDERSTORM WILL OCCUR, IMMEDIATELY STOP ALL OXYGEN FILLING OPERATIONS.

WARNING: KEEP ALL HYDROCARBONS (FUELS, LUBRICANTS, ETC.) AWAY FROM ALL SOURCE OF OXYGEN. OXYGEN BECOMES EXPLOSIVE WHEN IT TOUCHES HYDROCARBONS.

WARNING: CLEAN THE TOOLS AND MAKE SURE YOUR HANDS ARE CLEAN TO PREVENT CONTAMINATION OF THE OXYGEN SYSTEM.

WARNING: WHEN YOU DO WORK ON THE GASEOUS OXYGEN SYSTEM, MAKE SURE THAT YOU OBEY ALL THE APPLICABLE SAFETY PRECAUTIONS. IF YOU DO NOT OBEY THESE PRECAUTIONS, INJURY TO PERSONS AND/OR DAMAGE TO THE AIRCRAFT CAN OCCUR.

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TASK 12-34-24-869-001-A	Aircraft Bonding and Grounding (Earthing) for the Refuel/Defuel or Oxygen Servicing Operations

3. Job Set-up
Subtask 35-00-00-010-050-A

A. There is no special job set-up for this task.

4. Procedure
Subtask 35-00-00-860-050-A

A. Special Precautions when Working on a Gaseous Oxygen System
(1) Oxygen gas has these properties:

No color, no smell and no taste
Not flammable, but can help combustion to occur.
Is heavier than air and can collect in low-lying areas.
Is a dangerous material (Ref. UN 1072 oxygen, compressed).

(2) A fire or explosion can occur when these elements are present:

Oxygen
Flammable material
An ignition source.

If you remove one of these elements, fire/explosion CANNOT occur.
Keep all hydrocarbons (fuels, lubricants, etc.) away from all sources of oxygen. Oxygen becomes explosive when it touches hydrocarbons.
(3) Ignition sources can be:
(a) Heat, for example:
1 External heat from an open flame from cigarettes, matches, cigarette lighters and heaters.
2 Heat from an electrical malfunction.
3 Heat of compression, for example when oxygen gets too hot because of:

Oxygen pressure to high
Sudden opening or closing of oxygen valves (when pressure is released suddenly)
Molecule agitation, when you hit the oxygen cylinder with too much force.

(b) Hot particles or sparks, for example:
1 When you grind or cut metal.
(c) Electrical discharge from:
1 Static electricity
2 Short-circuit
3 Cell-phone operation
4 Lightning during a thunderstorm.
(d) Small quantity of hydrocarbon (petroleum), when it is mixed with pure oxygen.
(e) Impact, for example:
1 Particle impact from contamination of oxygen system with dust and debris.
2 Mechanical impact from:

A wrench falls onto a porous hydrocarbon (one large mechanical impact)
Tools fall on equipment or tubing (one large mechanical impact)
Component that chatters, (for example valve), when it is in operation (mechanical impact that occurs again and again)

NOTE: Make sure that you do a sound check for "chatter" for the related component.

"Chatter" can occur in multiple impacts in rapid succession on non-metal poppets or seats in this component . This impact causes heat that can cause ignition to the non-metal.
(f) Metal, when:

It is new, cut and touches an oxidizer
It hits equipment or other material and causes one large mechanical impact.

(4) An atmosphere with high oxygen concentration:
(a) Is specified as ambient air with an oxygen content of 24% or more.
(b) Humans cannot sense it.
(c) Before you enter an area, use an oxygen detector. If the concentration of oxygen is too high, make sure the area has a good airflow before you enter.
(d) A fire in a high oxygen concentration atmosphere has:

Higher intensity (burns faster)
Higher temperature
Higher thermal value (burns stronger).

(e) Pure oxygen at high pressure can cause fire, if it is mixed with these materials:

Oil
Grease
Textiles
Rubber.

These materials can burn very fast with high intensity. They may also cause a fast ignition.
(f) Usually, you cannot extinguish a fire until you isolate or remove the cause of fire.
(g) You must not help persons on fire directly, because this can put you at risk, too.
(h) For first aid, refer to the oxygen suppliers Material Safety Data-Sheet (MSDS).
(5) Hyperoxia is caused by too much oxygen:
(a) Can occur in ambient air with a high oxygen concentration.
(b) Symptoms can include:

Breathing problems
Vision changes
Dizziness
Coldness
Nausea
Tingling in the hands, feet and around the lips
Unconsciousness.

Remove them from the work area immediately.
Tell them to breathe slowly.

(6) Airflow:
(a) Make sure that there is a good airflow in the work area. This is to prevent a high oxygen concentration, if there is a leak.
(7) Clothes, skin and equipment:
(a) Make sure that your skin, clothes, equipment and tools are clean and clear of hydrocarbons (for example, fuel, lubricant).
(b) Clothes and hair can absorb oxygen. When you leave a work area high in oxygen concentration, you must stay away from a source of ignition for a minimum of 15 minutes. Smoking is not permitted.
(8) Safety:
(a) Before you do oxygen maintenance procedure, make sure that all other maintenance personnel in the aircraft:
1 Knows about the maintenance that will be done
2 Knows and obeys instructions of local occupational safety and fire department related to oxygen maintenance procedures.
(b) Crew and passengers are not permitted to be on aircraft during the oxygen filling and maintenance of gaseous oxygen system.
(c) During an oxygen maintenance procedure:
1 Obey maintenance procedure instructions warning and caution notes at all times.
2 Do all other maintenance procedures at more than 5 m (16.40 ft.) away from the work area of the aircraft.

NOTE: You may reduce the safety distance with the approval of local occupational safety and fire department personnel.

3 The procedures that follow are not permitted during oxygen maintenance:

Refuel
Repairs on fuel and hydraulic systems
Procedures that use flammable materials such as cleaning and de-icing
All procedures that can cause heat and flame or sparks (for example electrical procedures).

4 Make sure that ground power is not connected or disconnected during oxygen related procedures.
5 Make sure that the related documents have the correct effectivity.
(9) Oxygen servicing:
(a) Obey the national rules when you fill an oxygen system.
(b) Make sure that there are warning notices in position to tell persons not to operate electrical switches during oxygen operations.
(c) Grounding (earthing) and bonding of service equipment:

WARNING: BEFORE YOU DO THIS PROCEDURE, MAKE SURE THAT THE OXYGEN GROUND FILLING EQUIPMENT IS ELECTRICALLY BONDED TO THE AIRCRAFT. IF THIS EQUIPMENT IS NOT CORRECTLY BONDED, AN ELECTRICAL DISCHARGE CAN OCCUR WHICH CAN CAUSE AN EXPLOSION OR FIRE.

1 Obey the local regulations for grounding (earthing) the aircraft. If you must ground (earth) the aircraft:

Ground (earth) the oxygen ground filling-equipment and aircraft correctly (Ref. AMM TASK 12-34-24-869-001).

2 You must bond the oxygen ground filling-equipment to the aircraft (Ref. AMM TASK 12-34-24-869-001).
(d) Make sure that there is no ignition source in a radius of less than 15 m (49.21 ft.) of the oxygen ground cart.

NOTE: You may reduce the safety distance with the approval of local occupational safety and fire department personnel.

(e) Stop oxygen related procedures:

When there is a thunderstorm
When other maintenance personnel do not follow safety instructions near the oxygen system
If the pressure in the oxygen cylinders does not increase continuously and at the same time.

(f) Only use the Airbus-specified Aviators Breathing Oxygen (ABO).
(g) Carefully read the oxygen suppliers Material Safety Data-Sheet (MSDS).
(10) High pressure oxygen cylinders:
(a) Open the manual shutoff valves on all oxygen cylinders slowly to make sure that the temperature does not increase suddenly.
(b) Close the manual shutoff valves with your hands. Do not use tools. To much force can cause damage to the valves.
(11) Removal and installation of oxygen components:
(a) Use only Ground Support Equipment (GSE) approved for use with oxygen systems.
(b) Make sure that the manual shutoff valves on all of the oxygen cylinders are closed before you remove connections in an oxygen system.
(c) Do not touch connections and internal parts of an oxygen system with bare hands. Use hand protection such as clean, lint-free cotton gloves.
(d) Make sure that the work area is clean and clear of dust and loose objects.
(e) Use only approved tools, procedures and materials to service and clean components in an oxygen system.
(f) Make sure that there are no hydrocarbons in the work area such as fuel and lubricants.
(g) Make sure that there are no flammable materials in the work area such as paint, thinners, cleaning solvents and dust.
(h) Do not loosen or tighten connections when the system is pressurized.
(i) During removal/installation procedures:

Make sure to put blanking plugs immediately on the pipes and components on removal (unless differently specified).
Make sure that the blanking plugs are new, oxygen clean and dry.
Use one new clean vinyl bag for each pipe or unit.
Put the pipe or unit in the bag and seal it.
Prevent contamination in an oxygen system because contamination in the system can cause damage to the system a fire or explosion.

(j) Make sure that disconnected pipe ends are safetied correctly, and are not dangerous to persons in the area around them.

NOTE: Safety loose equipment, pipes or hoses.

(k) Only use lubricants and thread compounds specially approved for oxygen systems.
(l) Make sure that you hold heavy components and assemblies correctly and carefully.
(m) Two wrenches are used to decrease stress on the components. Use the two wrenches, one for the nut and one for the union, to connect or disconnect a line connection.
(n) Make sure that flexible hoses are not twisted or pulled tightly.
(o) Make sure that all system connections are torqued to the correct value given by the maintenance manual.
(p) Open/close spring-loaded clamps carefully to prevent damage to electrical harnesses.
(q) Make sure that all the quick disconnects are connected properly.
(r) Make sure the bonding strips and clamps are in the correct condition during the installation.
(s) After servicing, make sure that the circuit breakers are closed and the tags removed (unless differently specified in the procedure).
(12) Leak detection:
(a) Make sure that leak detection products and test equipment are:

Approved for oxygen systems
Identified with "for oxygen use only" labels.

(b) Make sure that all fixtures, tools, test and support equipment specified by the maintenance manual are applicable to the aircraft.

[Rev.10 from 2021] 2026.04.01 01:03:36 UTC