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1 This guidebook and its companion Emission Inventory Analysis Tool (EIAT) have been devel- oped as part of the Airport Cooperative Research Program (ACRP) Project 02-34, âQuantifying Aircraft Lead Emissions at Airports.â They encompass a series of best practices and guidance for estimating airport lead emissions from piston-powered aircraft fueled with aviation gasoline [or 100 grade âlow leadâ (100LL)] containing tetraethyl lead. The best practices identified herein are intended to supplement (and not replace) the current Federal Aviation Administration (FAA) and Environmental Protection Agency (EPA) default methods for lead inventory preparation. EPA must approve any lead inventory methods used for regulatory purposes. The EIAT allows users to select either FAA/EPA defaults or average site-specific results from ACRP 02-34 for inventory development or provide airport-specific inputs. At a minimum, the user must supply airport-specific annual operations data in order to estimate annual lead emissions. FAA/EPA default methods are consistent with those utilized in the EPAâs triennial National Emissions Inventory (NEI). At the most basic level, the EIAT replicates the NEI method. How- ever, the primary purpose of the EIAT is to allow inventories to be based on the enhanced inventory methodology developed as part of ACRP 02-34. Although two sets of default data are available, it is recommended that airport-specific data be obtained and used as input to the EIAT whenever feasible. The EIAT allows users to incrementally modify the inventory methodologyâ incorporating additional details or airport-specific data in place of default data and assumptions. The most significant recommendations for inventory development are summarized as follows: 1. Piston aircraft lead inventory development needs to incorporate the emissions occurring during flight-check run-up procedures (i.e., the magneto test). High lead concentrations were observed in the ACRP 02-34 air quality modeling specifically in the run-up areas. This guidebook provides a method and supporting data such that this inventory element can be addressed with no additional user input. 2. Currently, there is no reliable data source for airport-level piston operations, whereas total airport operations are widely available. The piston engine share of aircraft activity is poorly quantified by publicly available data and current methods. It is recommended that airport collection of activity-based aircraft tail numbers be completed for purposes of (1) calculating the piston-engine share of aircraft operations and (2) improving the accuracy of fleet-average aviation gasoline consumption rates (based on the locally observed fleet). The EIAT is designed to incorporate these piston fleet data, if collected, into the inventory analysis method. 3. It is recommended that airport sampling of aviation gasoline be completed to determine typical, local lead content of fuel dispensed. Current inventory methods model lead content as the maximum allowable, whereas the limited data available show that there is considerable C H A P T E R 1 Summary
2 Best Practices Guidebook for Preparing Lead Emission Inventories from Piston-Powered Aircraft with the Emission Inventory Analysis Tool variation in lead content from airport-collected gasoline samples. The EIAT allows for model- ing with airport-specific gasoline lead content. 4. The standard modes of operation included in existing inventory methods are not adequate to address commercial flight school activities, which are common at many general aviation airports. For the three airports of study in ACRP 02-34, âcontinuousâ operations (i.e., those associated with training procedures) accounted for about 40 percent of all piston operations. The emissions characteristics of continuous modes are distinct and not modeled adequately by current inventory methods. The EIAT can address these modes of operation; however, the frequency of occurrence will be airport specific and should be based on locally collected data. 5. The amount of time spent in each mode, termed âtime in modeâ (TIM), is variable and depends on the airport configuration and the individual piston-engine aircraft. Local collec- tion of TIM data is a means to improve the airport-specific inventory, and the EIAT facilitates the incorporation of TIM data into the inventory method. 6. If airport-specific fuel consumption rates are not calculated from a local aircraft fleet assess- ment (i.e., the primary recommendation), then the secondary recommendation is that average fuel consumption rates from ACRP 02-34 be used in place of FAA/EPA defaults. The under lying data, fuel rate assignment method, and activity-weighting assumptions of the ACRP 02-34 averages are all significant improvements over the methods used to create the FAA/EPA default fuel consumption rates.