Q12-10. What type of aircraft fire-fighting rescue vehicles are used at shore-based activities? Q12-11. What type of aircraft fire-fighting rescue vehicles are used aboard aircraft carriers? Q12-12. What type of fire-fighting agents are contained in the Twinned Agent Unit (TAU-2H)? AIRCRAFT FIRE HAZARDS LEARNING  OBJECTIVE: Identify the different hazards associated with aircraft fires, and recognize aircraft fluid line identification markings. Not every crash results in fire. The responsibility of the crash fire fighter does not end when fire fails to occur. Serious actual and potential fire hazards may have been created, which you must eliminate or minimize without delay. The greater the damage to the aircraft, the greater the possibility of fuel spillage. A spark or a hot engine part could ignite fuel vapors and set off a full-fledged fire. You should take every precaution to guard against accidental ignition. Personal laxity or unfamiliarity with ordinary preventive measures could allow a delayed fire to occur, which could endanger personnel. FLAMMABLE, HAZARDOUS, AND FIRE ACCELERATING MATERIALS Accelerating materials carried on aircraft are of major concern to the aircraft rescue and fire-fighting crews. Aviation gasoline (AVGAS), jet fuels (JP-4, JP-5, and JP-8), engine oils, oxygen systems, and hydraulic fluids constitute problems in aircraft fire-fighting. Some of these fuels have restrictions as to where they can be used; for example, JP-4 is prohibited aboard ship due to its flash point. CAUTION Under aircraft crash impact conditions where fuel-air mixtures or mists are created, all fuels are easily ignited. Aviation Gasoline (AVGAS) The flash point (by closed cup method at sea level) of AVGAS is -50°F (-46°C). The rate of flame spread has also been calculated to be between 700 and 800 feet per minute. JP-4 Fuel JP-4 jet fuel is a blend of gasoline and kerosene and has a flash point from -10°F (-23°C). The rate of flame spread has also been calculated to be between 700 and 800 feet per minute. JP-5 Fuel JP-5 fuel is a kerosene grade with a flash point of 140°F (60°C). The rate of flame spread has been calculated to be in the order of 100 feet per minute. The lowest flash point considered safe for use aboard naval vessels is 140°F (60°C). FUEL TANKS When an aircraft crashes, the impact usually ruptures the fuel lines and fuel tanks. Ordinarily, all the fuel is not liberated at once. There is a source of fuel that is supplying the fire either from the rupture in the tank or from the loosened and ruptured fuel lines in the accessory section of the engine. The control of the fire around the fuselage section under these conditions presents a very complex problem. The top portion of the tank is more void of liquid than any other section of the tank. Because of the restraining cushion of the liquid itself, the explosive force will be directed upward instead of downward or on a horizontal plane. Fuel loads can vary from 30 gallons in small aircraft to approximately 50,000 gallons in large jet aircraft. Fuel tanks are installed in a variety of places within the aircraft structural framework or as a built-in part of the wing. Fuel tanks are often carried under the floor area in the fuselage of helicopters. You should refer to NATOPS U.S. Navy Aircraft Emergency Rescue Information Manual, NAVAIR 00-80R-14-1, for the exact location of fuel tanks on a particular aircraft. Upon severe impact these tanks generally rupture and result in fire. Many naval aircraft are provided with external auxiliary fuel tanks located under the wings and fuselages. The aircraft manufacturers conducted a number of tests on external aircraft fuels tanks in which they were exposed to an enveloping fuel fire. These studies show that there were no deflagrations. The tanks did melt or rupture, releasing fuel onto the decks. The time to fuel tank failure (release of fuel) was dependent on the percent of fuel in the tank and ranged from 28 seconds for a 10-percent load to 3 1/2 minutes for a 100-percent load. 12-13