for Emission Inventory Preparation , Volume IV, Chapter 5 (for both civil and military aircraft  engines) and the ICAO’s  Engine Exhaust Emissions Databank  (for civil aircraft engines only).  Potential sources of site-specific data on engine types being tested include airline maintenance,  and sampling. If site-specific engine data for commercial airlines is not available but the aircraft  operator is known, then an appropriate default engine can be chosen based on the operator’s  national fleet. Airline fleet data, including aircraft engine model, is published in Bucher & Co.’s  JP Airline-Fleets International. If the aircraft operator is not known, default, typical aircraft - engine data is provided in Chapter 5 of EPA’s  Procedures for Emission Inventory Preparation,  IV: Mobile Source . For military aircraft, site -specific information on engine types being  tested  may be obtained from the maintenance personnel performing the testing. Default military aircraft  engine data is also listed in the  EPA’s  Procedures for Emission Inventory Preparation, IV:  Mobile Source .  Typical non-combustion stationary and area sources (e.g., fuel tanks, cooling towers, etc.) found  at airports are described in the following sections. The methodologies used to calculate emissions  from these sources varies depending on the type of source and the pollutant specific to source.  Many airports have fuel farms where large quantities of jet fuel,  avgas, gasoline and other fuel  types are stored in tanks. Fuel storage and handling activities represent sources of evaporative  hydrocarbon emissions. Emissions from these sources occur from  “breathing losses” (or  “standing losses”) and “working losses” (or “withdrawal losses”).  Breathing losses are the  result of the natural expansion and contraction of the fuel caused by  changes in ambient temperature and the resultant evaporative emissions escaping from the fuel  storage tanks.  Working losses are the combined los ses from filling and emptying the stor age tanks. Filling  causes increased pressure in the tank, thus expelling vapors from the tank. Emptying losses occur  when air drawn into the storage tank during fuel removal becomes saturated with hydrocarbon  vapors, expands, thus exceeding the vapor space capacity, and is expelled out of the Working losses also occur during the refueling of aircraft and fuel trucks. The level of emissions  depend on the type of storage device, the type and amount of fuel stored, transfer and refueling  methods, efficiency of vapor recovery and atmospheric conditions (i.e., temperature and relative  humidity).  Table A5-3  ( Evaporative Emission Losses of Fuel Storage Tanks ) summarizes the fuel storage  tanks commonly found at airports and the various ways evaporative emissions escape from these  sources.  31$_{ }$ A5.3  Non-Combustion Sources  A5.3.1  Fuel Storage Tanks  A5.2.6.5 Engine Type  APPENDIX A5$_{ }$