Best Practices Guidebook for Preparing Lead Emission Inventories from Piston-Powered Aircraft with the Emission Inventory Analysis Tool (2015)

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32 7.1 Overview There is a single worksheet, denoted with a yellow-shaded tab in the EIAT, where inter- mediary calculations are performed and displayed. The final inventory results are presented in Worksheet 8.1. Worksheet 7.1 contains the intermediary inventory calculations. These data may be of inter- est to further document the inventory results or to provide QA/QC checks of the inventory analysis. 7.2 Calculations: Worksheet 7.1 Worksheet 7.1 performs the aircraft operations, fuel consumption, and inventory calcu- lations. There are no required actions or optional actions. There is one inventory modeling parameter set in this worksheet—the “Pb [lead] retention rate.” The Pb retention rate in the analysis is assumed by the 2011 NEI documentation, which was updated in the context of the 2008 NAAQS rulemaking. The Pb retention rate is the amount of fuel Pb that ends up on engine hardware or in engine fuel (and thereby is not emitted as exhaust). The Pb retention rate assumed is 5 percent. It is not a parameter that would vary locally or would be examined locally. As such, it is not a variable likely to be modified in the inventory analysis. Overall, the Pb inventory calculations also follow those of the 2011 NEI documentation. The general inventory equation employed by the EIAT is as follows: Pb Emissions grams 1 Pb Retention TIM min 60 min hr Fuel Rate lb hr Pb Content g gal Density lb gal ( ) ( )( )( ) ( ) ( ) ( )= − × × × Emission inventory calculations are expressed in grams or tons, where tons reported in this method are always U.S. short tons (i.e., 1 ton = 2,000 pounds). Microsoft Excel conversion func- tions are used to convert between grams and tons. The calculations are performed incrementally in the following 11 distinct steps. These steps are shown separately for review and reporting from the EIAT. 1. Aircraft Operations, Annual 2. Piston Operations by Landing/Takeoff Mode, Annual 3. Modal Events per Year (Piston Aircraft) Inventory Calculations C H A P T E R 7

Inventory Calculations 33 4. Total Piston Hours by Mode 5. Aviation Gasoline Emission Rate by Mode (pounds/hour) 6. Aviation Gasoline Consumption (gallons) 7. Aviation Gasoline Consumption (gallons per piston operation) 8. Lead Inventory (tons) 9. Pb Emission Rate (grams per total piston operation) 10. Pb Emission Rate (grams per piston operation by aircraft type) 11. Pb Emission Rate (grams per total operations)