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

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14 4.1 Overview There are six worksheets denoted with green-shaded tabs in the EIAT for the input and processing of aircraft fleet data. These data define the proportion of operations by fixed-wing aircraft and rotorcraft and the proportion of piston engines within those two aircraft types. Moreover, the user has the option to input detailed piston-powered aircraft data to determine airport-specific aviation fuel consumption rates. • Worksheet 4.1 establishes the proportions of operations from FW aircraft, the FW operations conducted by piston engines, and the RC operations by piston engines for the inventory. • Worksheet 4.2 assigns fuel consumption rates based on a user-selected approach. • Worksheets 4.3 and 4.4 define the airport-specific piston-engine fleets to support the option of incorporating facility-specific, piston-engine fuel consumption rates. • Worksheets 4.5 and 4.6 contain data on fuel consumption rates and example piston aircraft information to support the application of the enhanced methodology using facility-specific aircraft data (Worksheets 4.3 and 4.4). 4.2 Aircraft Fleet: Worksheet 4.1 Worksheet 4.1 is where the data are input; these data are needed to apportion the total opera- tions (supplied by the user from Worksheet 3.1) into FW and RC shares and into piston-engine shares of both aircraft types. Proportions are to be based on observed operations (i.e., activity based). There is one required action for this worksheet: select the approach option for the source of the fleet apportionment data. There are two optional actions for this worksheet where the user supplies additional data if “current FAA/EPA default” or “facility-specific approach” options are selected. Table 7 summarizes the options for entering annual operations data; this table also appears in Worksheet 4.1. The preferred approach is that facility-specific data are collected and entered. In the absence of this, the user must specify the use of one of two screening approaches: current FAA/EPA defaults or ACRP 02-34 results. The option selected then defines the source of values for the following three parameters: the percentage of operations from FW aircraft, the share of FW operations by piston engines, and the share of RC operations by piston engines. The parameters assigned for the two screening inventory options are presented in Table 8. Note that the percentage of operations from RC in the methodology is equal to 100 percent minus the percentage of operation from FW aircraft. C H A P T E R 4 Aircraft Fleet Data

Aircraft Fleet Data 15 An important clarification must be made regarding which FAA/EPA default method is applied in the enhanced methodology for defining the piston-engine share of FW aircraft operations. The 2011 NEI documentation employs two methods: use of airport-based aircraft data from FAA Form 5010 (Airport Master Record), and use of national default survey data for airports without based aircraft data (U.S. EPA 2013b). The enhanced methodology uses the latter— national default survey data—estimating that 21.8 and 72.1 percent of air taxi and general avia- tion operations, respectively, were from piston-powered aircraft (as reported in Table 8). For the following reasons, the enhanced methodology does not incorporate the 2011 NEI methodology based on the use of FAA Form 5010 based aircraft population data to approximate the piston share of FW aircraft operations: 1. The 2011 NEI documentation mistakenly states that the Form 5010 reporting for airport aircraft populations for single-engine and multi-engine aircraft represents piston-powered aircraft only. It was confirmed with the FAA that these values (both single-engine and multi- engine) are the combination of piston-engine and turboprop-engine airplanes as reported in Form 5010, and turboprop engines are not piston engines. 2. The study that the 2011 NEI documentation claims validates this approach also does not distinguish between piston and turboprop engines (Louis Berger Group 2010); therefore, this specific population-based approach has not been validated with piston-only operations. Inventory Option Title Description Screen 1 FAA/EPA Default EPA default assumptions for apportioning total annual operations between FW aircraft and RC and for piston shares by aircraft type. Additional user input may be required. Screen 2 ACRP 02-34 Data ACRP 02-34 data (average over three airports) for apportioning total annual operations between FW aircraft and RC and for piston shares by aircraft type. Facility Specific Facility Data, User Supplied User-supplied, facility-specific data for apportioning annual operations between FW aircraft and RC for piston shares by aircraft type. Additional user input is required. Table 7. Inventory options for apportioning operations by aircraft and engine type. Inventory Option Parameter Activity-Based Proportions by Aircraft Class Air Carrier Air Taxi General Aviation Military FAA/EPA Default % of Operations from FWa 100.00% 100.00% 100.00% 100.00% % of FW Operations by Piston Engines 0.00% 21.80% 72.10% 0.00% % of RC Operations by Piston Engines 0.00% 2.00% 35.80% 0.00% ACRP 02-34 Data % of Operations from FW 100.00% 98.99% 98.99% 100.00% % of FW Operations by Piston Engines 0.00% 80.98% 80.98% 0.00% % of RC Operations by Piston Engines 0.00% 37.36% 37.36% 0.00% a Note that the FAA/EPA defaults assume one of two cases—100 percent operation by FW aircraft or 100 percent operation by RC, depending on whether the facility is listed as “airport” or “heliport,” respectively, in FAA Form 5010 (Airport Master Record), which requires the user to input these values based on the facility type under evaluation. The values shown here are reflective of airports. Table 8. Aircraft/engine apportionment parameters for screening inventory options.

16 Best Practices Guidebook for Preparing Lead Emission Inventories from Piston-Powered Aircraft with the Emission Inventory Analysis Tool 3. An aircraft population-based approach for determining the piston-engine share should be made only if (1) exclusively piston-powered aircraft populations are known and (2) airport operations are predominantly private only or commercial only (but not a mixture of both, as the usage rates are significantly different by ownership types). The preferred approach option is to collect and implement facility-specific data and modeling parameters. The recommended approach for implementing this option is to capture operation- based aircraft tail number data. Correlating these data with the FAA tail number registry will produce a breakdown of operations by piston and non-piston engines, RC, and FW aircraft. Additionally, the use of tail number data and FAA registry data is the resource for Section 4.4 of this guidebook under the discussion of detailed piston fleet data used to support the develop- ment of average-fleet piston-engine fuel rates. The approach and setup for capturing aircraft tail number data are described in ACRP Web- Only Document 21 (Heiken et al. 2014). Aircraft tail numbers are matched to the specific air- frame and engine parameters through the data contained in FAA’s Aircraft Registry database. The downloadable database (http://www.faa.gov/licenses_certificates/aircraft_certification/ aircraft_registry/releasable_aircraft_download/) contains a compressed file with several comma-delimited text files. The MASTER.txt file is the tail number registry (i.e., N-number registry). If the tail number is not found, the user should also search the DEREG.txt file (i.e., deregistered planes file) for the tail number. The tail number record is combined with the data in files ACFTREF.txt (aircraft reference file) and ENGINE.txt (engine reference file) to produce the fleet data needed for this evaluation. The following four engine types in the registry data are piston engines: reciprocating, 2-cycle, 4-cycle, and rotary. Note that turboprop-powered aircraft have propellers, and it is important to understand that the mere presence of propellers is not the sole indicator of a piston engine (albeit most propeller aircraft are equipped with piston engines). Accurate visual differentiation between turboprop propellers and piston propellers while collecting facility data is not probable, and tail number identification should be employed for obtaining operations data by engine type. Note that ACRP 02-34 researchers evaluated whether the use of airport-specific aircraft data recorded in FAA’s Traffic Flow Management System Counts (TFMSC)—previously known as ETMSC—could provide a resource of airport piston proportions and piston fleet details. It was determined that a sampling bias in the subset of aircraft captured made the Traffic Flow Man- agement System Counts inaccurate and unusable for estimating airport-specific piston fleets and their proportions to total airport activity (Heiken et al. 2014). It is strongly recommended that this resource not be utilized in lead emission inventory development from piston engines. 4.3 Piston Fuel Rates: Worksheet 4.2 Worksheet 4.2 is where the fuel rate assignment options are set and where the screening values for fleet-average, piston-engine fuel consumption rates enter into the EIAT. Separate options for assigning fuel rates can be implemented for FW aircraft and RC. Fuel consumption rates are specific to each individual operating mode (the modes of operation are discussed in Chapter 5 of this guidebook). There are two required actions for this worksheet: 1. Select the approach option for piston-engine FW aircraft fuel rates and 2. Select the approach option for piston-engine RC fuel rates. Tables 9 and 10 summarize the options for fuel rate assignment for FW aircraft and RC, respectively. If the user selects facility-specific rates (for either aircraft type), the data input and

Aircraft Fleet Data 17 calculations occur elsewhere in Worksheets 4.3 and 4.4, and no further data entry is required in this worksheet. If the user selects either screening approach (for either aircraft type), those screening values are presented in this worksheet. Table 11 presents the fleet-average, piston-engine fuel consumption rates for the two screen- ing inventory options. The FAA/EPA defaults shown were determined by extracting modal fuel consumption rates from EDMS and following the documented weighting factors in the 2011 NEI. FAA/EPA defaults for the “run-up” and “touch-and-go ground roll” modes do not exist in EDMS and were estimated. These “default” modal values were calculated from the same set of engines used for the remaining FAA/EPA default values, using the procedures and assumptions specific to these operation modes. This addition to the FAA/EPA default fuel consumption rates was completed so that the full range of operating modes could be assessed with FAA/EPA default fuel rates, if such a scenario were selected by the EIAT user. Inventory Option Title Description Screen 1 FAA/EPA Default EPA default fuel consumption rates for piston-powered FW aircraft. Screen 2 ACRP 02-34 Data Activity-weighted average fuel consumption rates observed for three airports. Facility Specific Facility Data, User Supplied Fuel consumption rates estimated from detailed aircraft fleet data supplied by user. User data entered in Worksheet 4.3. Table 9. Options for assigning piston-engine FW aircraft fuel rates. Inventory Option Title Description Screen 1 FAA/EPA Default EPA default fuel consumption rates for piston-powered RC. Screen 2 ACRP 02-34 Data Activity-weighted average fuel consumption rates observed for three airports. Facility Specific Facility Data, User Supplied Fuel consumption rates estimated from detailed aircraft fleet data supplied by user. User data entered in Worksheet 4.4. Table 10. Options for assigning piston-engine RC fuel rates. Operation Mode FAA/EPA Default ACRP 02-34 Data Fixed-Wing Aircraft Rotorcraft Fixed-Wing Aircraft Rotorcraft Takeoff 147.6 n/a 117.3 n/a Climb-out 112.7 101.1 92.5 115.0 Approach 62.0 55.0 52.4 72.4 Taxi/Idle 14.2 12.6 15.4 40.4 Run-up 66.5 a 70.6 a 55.7 62.5 Touch-and-Go Ground Roll 80.9 a n/a 66.35 n/a a Note that FAA/EPA default values for “run-up” and “touch-and-go ground roll” operating modes were estimated from the aircraft engine data used by EPA to define defaults for the remaining modes. Table 11. Modal gasoline consumption rates for piston engines (lb/hr) by screening approach option.

18 Best Practices Guidebook for Preparing Lead Emission Inventories from Piston-Powered Aircraft with the Emission Inventory Analysis Tool Tables 12 and 13 present additional information on the number of engines and the underly- ing distribution of engines used to develop the screening fuel consumption rates for the FAA/ EPA and ACRP 02-34 screening options, respectively. Table 12 presents the proportional mix of six engines used to calculate the FAA/EPA default fuel consumption rates; these are based on the 2011 NEI documentation. Table 13 presents the engines and weighting used for the ACRP 02-34 screening values; there are 28 gasoline-powered piston engines and 23 unique emission rates estimated by the ACRP 02-34 methodology. The ACRP 02-34 weighting factors are activity based across the three airports evaluated. Additional comments and remarks on the use of Worksheet 4.2 are as follows: 1. If screening-based fuel consumption rates are used in an inventory analysis, it is recom- mended that the values from ACRP 02-34 be used as the underlying data because its fuel rate method and weighting assumptions are improvements over the methods used to create the FAA/EPA defaults. 2. Engine load assumptions for RC differ by approach option selected in Worksheet 4.2 (see Table 10). For the “FAA/EPA default” option, the RC engine load assumptions do not differ from the engine load assumptions for FW aircraft (for the same mode)—a notably poor assumption. Conversely, for the two options of “ACRP 02-34 Data” and “Facility Data, User Supplied,” the enhanced method includes the RC-specific recommended load points from the Swiss FOCA (Switzerland Federal Office of Civil Association 2009). Loads of 20, 60, and 95 percent are assumed for idle/taxi, approach, and climb-out, respectively, based on the detailed FOCA study of helicopter operations and emissions. 3. There is a compression-ignition (CI) category of piston engines in the enhanced methodol- ogy (as shown in Table 13). These engines are similar to diesel-powered automotive engines, and aircraft CI engines burn jet fuel rather than aviation gasoline. In the enhanced method, the CI piston engines (observed about 1 percent of the time in ACRP 02-34) are assigned a gasoline consumption rate of zero, as these engines do not consume aviation gasoline. With the zero-level fuel consumption rate, these engines are then treated as any other piston engine in the inventory analysis. Engine Manufacturera Engine Model Engine/Fuel Metering Technology Engine Distribution Fixed-Wing Rotorcraft Lycoming IO-320-DIAD Fuel-injected, horizontally opposed, 4-stroke 15% 25% Continental IO-360-B Fuel-injected, horizontally opposed, 4-stroke 15% 25% Continental O-200 Carbureted, horizontally opposed, 4-stroke 15% 0% Lycoming O-320 Carbureted, horizontally opposed, 4-stroke 15% 25% Lycoming TIO-540-J2B2 Turbocharged, fuel-injected, horizontally opposed, 4-stroke 20% 0% Continental TSIO-360C Turbocharged, fuel-injected, horizontally opposed, 4 stroke 20% 25% a “Continental” refers to both “Continental Aircraft Engine Company” and “Teledyne Continental Motors”; “Lycoming” refers to both “Lycoming” and “Textron Lycoming.” Table 12. Six piston engines from EDMS used to define FAA/EPA default fuel consumption rates.

Aircraft Fleet Data 19 4.4 Detailed Piston Fleet Data: Worksheets 4.3 and 4.4 Worksheets 4.3 and 4.4 are where the user supplies the airport-specific piston-engine fleets to support the option of developing facility-specific, piston-engine fuel consumption rates. Both Worksheets 4.3 and 4.4 are described herein, as the format and function is nearly identical. Worksheet 4.3 is user-supplied FW aircraft data; Worksheet 4.4 is user-supplied RC data. There are no required user actions for this worksheet. There are two optional actions that need to be taken if the user has selected the “Facility Data, User Supplied” option for either FW aircraft or RC in Worksheet 4.2. 1. If the “Facility Data, User Supplied” option is selected for FW aircraft in Worksheet 4.2, then the aircraft data in Worksheet 4.3 must be entered. Technology Group Engine Manufacturer & Model Number or Engine Displacementa Engine Count for Fuel Rate Development Engine Distribution Observed in ACRP 02-34 Fixed-Wing Aircraft Rotorcraft 4-Stroke Horizontal Compression Ignition (CI) All n/a 0.7% 0.0% 4-Stroke Horizontal Spark Ignition (SI), Carbureted Default 8 16.3% 30.0% Lycoming 320 2 16.3% 0.0% Lycoming 360 1 10.3% 0.0% Lycoming 540 1 1.3% 0.0% Rotax 912 2 3.5% 0.0% Continental 200 1 0.5% 0.0% Continental 6-285 1 0.0% 0.0% 4-Stroke Horizontal SI, Fuel Injection Default 8 6.7% 0.0% Lycoming 320 2 0.2% 0.0% Lycoming 360 1 27.4% 70.0% Lycoming 540 2 2.1% 0.0% Continental 360 1 2.0% 0.0% Continental 550 2 3.0% 0.0% 4-Stroke Horizontal SI, Turbocharged Default 9 0.2% 0.0% Lycoming 540 3 2.8% 0.0% Rotax 914 1 0.0% 0.0% Continental 360 1 1.0% 0.0% Continental 520 1 3.7% 0.0% Continental 550 3 0.6% 0.0% 4-Stroke Radial SI Default 2 1.5% 0.0% Wright 1820b 1 0.0% 0.0% 2-Stroke Horizontal SI Rotax 582 1 0.0% 0.0% a “Continental” refers to both “Continental Aircraft Engine Company” and “Teledyne Continental Motors”; “Lycoming” refers to both “Lycoming” and “Textron Lycoming.” b The Wright R-1820 engine was observed at the field study conducted at the Centennial Airport (Denver, Colorado) but was omitted from this screening approach. The Boeing B-17 (known as the Flying Fortress) has four large Wright 1820 radial engines; the aircraft’s fuel consumption rates are 40 to 50 times higher than the average general aviation plane. This aircraft was present for a special event and may not be suitably representative as a screening value. Table 13. Engine distribution used to develop ACRP 02-34 screening-case fuel consumption rates.

20 Best Practices Guidebook for Preparing Lead Emission Inventories from Piston-Powered Aircraft with the Emission Inventory Analysis Tool 2. If the “Facility Data, User Supplied” option is selected for RC in Worksheet 4.2, then the air- craft data in Worksheet 4.4 must be entered. The recommended approach for acquiring fleet data, as applied in the field studies of ACRP 02-34, is to capture operation-based aircraft tail number data. Correlating these data with the FAA tail number registry will produce a breakdown of operations by piston and non-piston engines, RC, and FW aircraft. Additionally, the use of tail number data and FAA registry data is the recommended resource for Chapter 4.2 of this guidebook under the discussion of aircraft fleet apportionment data. The approach and setup for capturing aircraft tail number data are described in ACRP Web- Only Document 21 (Heiken et al. 2014). Aircraft tail numbers are matched to the specific air- frame and engine parameters through the data contained in FAA’s Aircraft Registry database. The database (http://www.faa.gov/licenses_certificates/aircraft_certification/aircraft_registry/ releasable_aircraft_download/) contains a compressed file with several comma-delimited text files. The MASTER.txt file is the tail number registry (i.e., N-number registry). If the tail num- ber is not found, the user should search the DEREG.txt file (i.e., deregistered planes file) for the tail number. The tail number record is combined with the data in files ACFTREF.txt (aircraft reference file) and ENGINE.txt (engine reference file) to produce the fleet data needed for this evaluation. Note that the following four engine types in the registry data are piston engines: reciprocating, 2-cycle, 4-cycle, and rotary. In Worksheets 4.3 and 4.4, the detailed aircraft fleet data entered are restricted to just the piston-engine aircraft. The following list provides the aircraft fleet defining parameters: • Tail number • Aircraft manufacturer • Aircraft model • Aircraft type • Manufacture year • Engine type • Engine manufacturer • Engine model • Engine horsepower • Displacement or model number • Number of engines Of the listed parameters, all but “displacement or model number” are found through the FAA registry. The displacement or model number is the numeric portion of the engine model, the value of which is pertinent to the BSFC database (Worksheet 4.5). Note that for Lycoming and Continental engine models, the numeric portion of the engine model is typically the engine displacement (in cubic inches). Of the listed parameters, only the values for “engine horsepower” and “number of engines” numerically enter into the emission inventory calculations. The remaining aircraft fleet iden- tifying parameters are useful in assigning BSFC rates and identifying the technology group (by which the BSFC data are organized). Additional comments and remarks for entering facility-specific piston-engine aircraft data are as follows: 1. Operational counts are supplied in Column M, allowing for weighting data based on the total counts observed. 2. In Column O, the user is responsible for assigning the BSFC rate to each entry from the 23 options available. The assignment process is described in Section 4.5. 3. Worksheets 4.3 and 4.4 can handle up to 1,000 unique aircraft entries.

Aircraft Fleet Data 21 4. The pre-existing data in Worksheets 4.3 and 4.4 (10 FW aircraft records and 6 RC records) are random, dummy data intended to facilitate understanding of the EIAT and the data entry of these worksheets. These pre-existing data are not representative of any case and should not be used in any inventory analysis. 5. As described in ACRP Web-Only Document 21 (Heiken et al. 2014), the calculation of fuel consumption rate from BSFC is completed according to the following formula: Fuel Rate Rared PowerMode lb hr BSFC lb hp hr Load hpMode Mode( ) ( )= −     × × 4.5 BSFC Data: Worksheet 4.5 Worksheet 4.5 contains the BSFC database developed in ACRP 02-34; ACRP Web-Only Docu- ment 21 (Heiken et al. 2014) should be consulted for further information related to their com- pilation, if needed. There are no required or optional actions associated with this worksheet; there are no user inputs or modifications to be completed in this worksheet. BSFC assignment to individual user-supplied piston-engine aircraft (Worksheets 4.3 and 4.4) is performed manually by the user. The assignment requires the user to determine the technol- ogy group to which the aircraft engine belongs. The BSFC data are organized by the following six technology groups: • 4-stroke horizontal spark-ignition (SI) engine, carbureted; • 4-stroke horizontal SI engine, fuel injected; • 4-stroke horizontal SI engine, turbocharged; • 4-stroke radial SI engine; • 2-stroke horizontal SI engine; and • 4-stroke horizontal CI engine. The following steps and criteria are used for BSFC assignment (pull-down menus in Column O of worksheets 4.3 and 4.4) using Worksheet 4.5: 1. Identify the technology group. 2. Within the technology group, assign the BSFC for the specific engine and model number if the engine and model number match the aircraft being assigned. 3. If the engine and model do not match, use the “default” BSFC within the technology group. The “engine model” shown in the BSFC database is the engine model with the leading letters and suffix letters removed. For example, the Continental TSIO-520 series engine falls under the “4-stroke horizontal SI engine, turbocharged” technology group and appears in the database as “Continental 520” within that group. For Lycoming and Continental engine models, the numeric portion of the engine model is typically the engine displacement (in cubic inches). Upon assignment of a few engines, it becomes readily apparent that the leading letters in the engine model are typically sufficient for defining the technology group. To facilitate the learning curve in assigning BSFC values, the complete set of unique aircraft identified in ACRP 02-34 field studies is provided in Worksheet 4.6. The aircraft data in Worksheet 4.6 include the BSFC assignment and can be used as a template for many common aircraft/engine combinations. Additional comments and remarks on the use of Worksheet 4.5 are as follows: 1. The BSFC values at the RC-specific load points are determined by interpolation in Work- sheet 4.5 (with the formula present in the worksheet). Fuel consumption test data obtained

22 Best Practices Guidebook for Preparing Lead Emission Inventories from Piston-Powered Aircraft with the Emission Inventory Analysis Tool in ACRP 02-34, which form the foundation of this database, did not test the RC-specific load points because these are not standard modes. 2. There is a CI category of piston engines in Worksheet 4.5 (described previously in Section 4.3 of this guidebook). The CI engines are piston engines that burn jet fuel and are assigned a BSFC value of zero in the enhanced methodology, as they do not consume aviation gasoline. 4.6 Example Piston Aircraft: Worksheet 4.6 Worksheet 4.6 contains the more than 300 unique piston-engine aircraft observed in the ACRP 02-34 site-specific data collection efforts. There are no required or optional actions for this worksheet; there are no user inputs or modi- fications to be completed for this worksheet. The purpose of including these data in the EIAT is to support the BSFC assignment process in Worksheet 4.5. These data are aircraft examples and have no function in the actual inven- tory calculations. The detailed aircraft parameters and the corresponding BSFC assignments are provided as searchable examples. Note that these data are not activity weighted and therefore any composite estimated from these data is not representative of any real-world case. These data, on whole, should not be used to estimate average fuel consumption rates because of the lack of an activity-based observation frequency.