Fire Safety and Protection

1-6 It takes three things to start a fire: OXYGEN, HEAT, FUEL Oxygen Friction (heat)Fuel pressure is held inside the container by some type of seal or frangible disk that is broken or punctured by a firing mechanism, usually a pin. This means that once the seal or disk is broken, pressure in the container is released and the fire extinguisher is spent, requiring replacement. [Figure 1-5] Halogenated hydrocarbon extinguishers are most effective on Class B and C fires. They can be used on Class A and D fires, but they are less effective. Halogenated hydrocarbon, commonly called Freon™ by the industry, are numbered according to chemical formulas with Halon™ numbers.

Carbon tetrachloride (Halon 104), chemical formula CCl 4, has an Underwriters Laboratory (UL) toxicity rating of 3. As such, it is extremely toxic. [Figure 1-6] Hydrochloric acid vapor, chlorine, and phosgene gas are produced whenever carbon tetrachloride is used on ordinary fires. The amount of phosgene gas is increased whenever carbon tetrachloride is brought in direct contact with hot metal, certain chemicals, or continuing electrical arcs. It is not approved for any fire extinguishing use. Old containers of Halon 104 found in or around shops or hangars should be disposed of in accordance with Environmental Protection Agency (EPA) regulations and local laws and ordinances.

Methyl bromide (Halon 1001), chemical formula CH 3Br, is a liquefied gas with a UL toxicity rating of 2. It is very toxic and corrosive to aluminum alloys, magnesium, and zinc. Halon 1001 is not recommended for aircraft use. Chlorobromomethane (Halon 1011), chemical formula CH2ClBr, is a liquefied gas with a UL toxicity rating of 3. Like methyl bromide, Halon 1011 is not recommended for aircraft use. Dibromodifluoromethane (Halon 1202), chemical formula CBr2F2, has a UL toxicity rating of 4. Halon 1202 is not recommended for aircraft use. Bromochlorodifluoromethane (Halon 1211), chemical formula CBrClF2, is a liquefied gas with a UL toxicity rating of 5. It is colorless, noncorrosive, and evaporates rapidly leaving no residue. It does not freeze or cause cold burns and does not harm fabrics, metals, or other materials it contacts. Halon 1211 acts rapidly on fires by producing a heavy blanketing mist that eliminates oxygen from the fire source. More importantly, it interferes chemically with the combustion process of the fire.

Furthermore, it has outstanding properties in preventing re- flash after the fire has been extinguished. Bromotrifluoromethane (Halon 1301), chemical formula CF3Br, is also a liquefied gas and has a UL toxicity rating of 6. It has all the characteristics of Halon 1211. The significant difference between the two is Halon 1211 forms a spray similar to CO2, while Halon 1301 has a vapor spray that is more difficult to direct. Note: The EPA has restricted Halon to its 1986 production level due to its effect on the ozone layer. Dry powder extinguishers, while effective on Class B and C fires, are best for use on Class D fires. The method of operation of dry powder fire extinguishers varies from gas cartridge charges, stored pressure within the container that forces the powder charge out of the container, to scooping pails or buckets of the powder from large containers or barrels to toss on the fire.

1-7 Extinguishing Materials Classes of Fire Self-Generating Self-Expelling Cartridge of N2 Cylinder Stored Pressure Pump Hand A B C D Water and antifreeze Soda-acid (water) Wetting agent Foam Loaded stream Multipurpose dry chemical Carbon dioxide Dry chemical Bromotrifluoromethane — Halon 1301 Bromochlorodifluoromethane — Halon 1211 Dry powder (metal fires) X X+ X X X X XX X+ X X+ X + Smaller sizes of these extinguishers are not recognized for use on these classes of fire. Group Definition Examples Gases or vapors in concentrations up to 20% by volume, for durations of exposure of up to approximately 2 hours, do not appear to produce injury.

Gases or vapors much less toxic than Group 4, but more toxic than Group 6. Gases or vapors in concentrations of the order of 2 to 2 ½%, for durations of exposure of up to approximately 2 hours are lethal or produce serious injury. Gases or vapors in concentrations of the order of 2 to 2 ½%, for durations of exposure of the order of 1 hour are lethal or produce serious injury. Gases or vapors in concentrations of approximately ½ to 1%, for durations of exposure of up to approximately ½ hour are lethal or produce serious injury. 6 (Least toxic) 5a 4 3 2 Carbon dioxide Dibromodifluormethane (Halon 1202) Bromochloromethane (Halon 1011) Bromotrifluoromethane (Halon 1301) Carbon tetrachloride (Halon 104) Methyl bromide (Halon 1001) Dry powder is not recommended for aircraft use, except on metal fires, as a fire extinguisher. The leftover chemical residues and dust often make cleanup difficult and can damage electronic or other delicate equipment.

Inspection of Fire Extinguishers Fire extinguishers need to be checked periodically utilizing a checklist. If a checklist is unavailable, check the following as a minimum: • Proper location of appropriate extinguisher • Safety seals unbroken • All external dirt and rust removed • Gauge or indicator in operable range • Proper weight • No nozzle obstruction • No obvious damage Airport or other local fire departments can usually help in preparing or providing extinguisher checklists. In addition, these fire departments can be helpful in answering questions 1-8 and assisting in obtaining repairs to or replacement of fire extinguishers.

Identifying Fire Extinguishers Fire extinguishers are marked to indicate suitability for a particular class of fire. The markings on Figure 1-7 must be placed on the fire extinguisher and in a conspicuous place in the vicinity of the fire extinguisher. When the location is marked, however, take extreme care to ensure that the fire extinguisher kept at that location is in fact the type depicted by the marking. In other words, if a location is marked for a Class B fire extinguisher, ensure that the fire extinguisher in that location is in fact suitable for Class B fires. Markings must be applied by decalcomanias (decals), painting, or similar methods. They are to be legible and as durable as necessary for the location. For example, markings used outside need to be more durable than those in the hangar or office spaces.

When markings are applied to the extinguisher, they are placed on the front of the shell, if one is installed, above or below the extinguisher nameplate. Markings must be large enough and in a form that is easily seen and identifiable by the average person with average eyesight at a distance of at least 3 feet. When markings are applied to wall panels, and so forth, in the vicinity of extinguishers, they must be large enough and in a form that is easily seen and identifiable by the average person with average eyesight at a distance of at least 25 feet. [Figure 1-8] Using Fire Extinguishers When using a fire extinguisher, ensure the correct type is used for the fire. Most extinguishers have a pin to pull that allows the handle to activate the agent. Stand back 8 feet and aim at the base of the fire or flames. Squeeze the lever and sweep side to side until the fire is extinguished.

Tie-Down Procedures

Preparation of Aircraft Aircraft are to be tied down after each flight to prevent damage from sudden storms. The direction that aircraft are to be parked and tied down is determined by prevailing or forecast wind direction. Aircraft are to be headed into the wind, depending on the locations of the parking area’s fixed tie-down points. Spacing of tie-downs need to allow for ample wingtip clearance. [Figure 1-9] After the aircraft is properly located, lock the nosewheel or the tail wheel in the fore-and-aft position. Tie-Down Procedures for Land Planes Securing Light Aircraft Light aircraft are most often secured with ropes tied only at the aircraft tie-down rings provided for securing purposes.

Rope is never to be tied to a lift strut, since this practice can bend a strut if the rope slips to a point where there is no slack. Since manila rope shrinks when wet, about 1 inch (1") of slack needs to be provided for movement. Too much slack, however, allows the aircraft to jerk against the ropes. Tight tie-down ropes put inverted flight stresses on the aircraft and many are not designed to take such loads. A tie-down rope holds no better than the knot. Anti-slip knots, such as the bowline, are quickly tied and are easy to untie. [Figure 1-10] Aircraft not equipped with tie-down fittings must be secured in accordance with the manufacturer’s instructions. Ropes are to be tied to outer ends of struts on high-wing monoplanes and suitable rings provided where structural conditions permit, if the manufacturer has not already provided them.

Securing Heavy Aircraft The normal tie-down procedure for heavy aircraft can be accomplished with rope or cable tie-down. The number of tie-downs are governed by anticipated weather conditions. Most heavy aircraft are equipped with surface control locks that are engaged or installed when the aircraft is secured. Since the method of locking controls vary on different types of aircraft, check the manufacturer’s instructions for proper installation or engaging procedures. If high winds are anticipated, control surface battens can also be installed to prevent damage. Figure 1-11 illustrates four common tie- down points on heavy aircraft.

The normal tie-down procedure for heavy aircraft includes the following: 1. Head aircraft into prevailing wind whenever possible. 2. Install control locks, all covers, and guards. 3. Chock all wheels fore and aft. [Figure 1-12] 4. Attach tie-down reels to aircraft tie-down loops, tie- down anchors, or tie-down stakes. Use tie-down stakes for temporary tie-down only. If tie-down reels are not available, 1⁄4" wire cable or 1 1⁄2" manila line may be used. Tie-Down Procedures for Seaplanes Seaplanes can be moored to a buoy, weather permitting, or tied to a dock. Weather causes wave action, and waves cause the seaplane to bob and roll. This bobbing and rolling while 1-9 COMBUSTIBLES ORDINARY CAPABILITY LIQUIDS FLAMMABLE EQUIPMENT ELECTRICAL COMBUSTIBLES ORDINARY LIQUIDS FLAMMABLE EQUIPMENT ELECTRICAL EQUIPMENT ELECTRICAL LIQUIDS FLAMMABLE METALS COMBUSTIBLE 1. Water 2. Carbon Dioxide, Dry Chemical Bromochlorodifluoromethane, and Bromotrifluoromethane 3. Multipurpose Dry Chemical 4. Multipurpose Dry Chemical (Insufficient Agent for ‘A’ Rating) 5. Dry Powder COMBUSTIBLES ORDINARY LIQUIDS FLAMMABLE EQUIPMENT ELECTRICAL METALS COMBUSTIBLE 6' 2' 3' 6' 10' + Major axis 3' Tie-Down Procedures for Ski Planes Ski planes are tied down, if the securing means are available, in the same manner as land planes. Ski-equipped airplanes can be secured on ice or in snow by using a device called a dead-man. A dead-man is any item at hand, such as a piece of pipe, log, and so forth, that a rope is attached to and buried in a snow or ice trench. Using caution to keep the free end of the rope dry and unfrozen, snow is packed in the trench.

If available, pour water into the trench; when it is frozen, tie down the aircraft with the free end of the rope. tied to a dock can cause damage. When warning of an impending storm is received and it is not possible to fly the aircraft out of the storm area, some compartments of the seaplane can be flooded, partially sinking the aircraft. Tie down the aircraft securely to anchors. Seaplanes tied down on land have been saved from high-wind damage by filling the floats with water in addition to tying the aircraft down in the usual manner. During heavy weather, if possible, remove the seaplane from the water and tie down in the same manner as a land plane. If this is not possible, the seaplane could be anchored in a sheltered area away from the wind and waves.