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14 ACRP Project 02-57 assessed two potential strategies to reduce piston-engine aircraft lead impacts besides the availability of unleaded AVGAS: (1) use of unleaded MOGAS in aircraft for which it is suitable, and (2) relocation of run-up areas. While each strategy offers the potential to reduce lead concentrations, there are other factors that should be considered before making a decision to implement either or both strategies. These factors are addressed in this chapter. 6.1 Unleaded MOGAS The vast majority of general aviation airports offer only a single gasoline grade for sale (100LL AVGAS) that can be used in all gasoline-powered, piston-engine aircraft. However, many general aviation aircraft can operate on unleaded ethanol-free MOGAS, which could potentially be made available at some airports. As discussed herein, there are several issues that should be considered before proceeding with efforts to make MOGAS available. 6.1.1 Confirming the Availability and Estimated Price of MOGAS The first step in evaluating the potential of the MOGAS strategy is to determine whether suit- able fuel is commercially available and, if so, what the approximate price differential is compared to AVGAS. Approaches to finding an ethanol-free MOGAS distributor include using online research/resources (Billing 2013), contacting local refineries and fuel distributors, and contacting other proximate airports that already distribute MOGAS. The grade of MOGAS that will be dispensed (87 or 91 AKI MOGAS) should also be considered: 91 AKI MOGAS can be used in a greater proportion of the piston-engine fleet (increasing the lead reduction potential), while 87 AKI MOGAS is expected to be less expensive (providing a greater financial incentive). Currently, over half of airports selling MOGAS dispense 91 AKI. With respect to prices, Figure 9 shows recent AVGAS and MOGAS price information as published online by airnav.com. Price spreads and differentials between MOGAS and AVGAS vary widely. However, it is important to understand the likely price differentialâif both fuels are available, it is unlikely that MOGAS would be used over AVGAS unless there is a cost savings. There may also be costs related to recovering the capital investment associated with the new refueling infrastructure. 6.1.2 Determining the Potential for MOGAS Use The proportion of aircraft approved for MOGAS operation will be facility-specific and facility variation in fleets (the number of aircraft that can operate on MOGAS vs. AVGAS) is significant, C H A P T E R 6 Other Factors to Consider When Evaluating Potential Strategies to Reduce Lead Impacts at General Aviation Airports
Other Factors to Consider When Evaluating Potential Strategies to Reduce Lead Impacts at General Aviation Airports 15 depending on geography, airport size, and aircraft types in operation. A survey of MOGAS sales at airports that already sell both MOGAS and AVGAS indicates that MOGAS sales are between 3 and 55 percent of total gasoline sales, with typical sales around 10 percent of the facilityâs gasoline total (KB Environmental Sciences 2014). Because new refueling infrastructure would be required for an airport that does not already have MOGAS, the potential of the local aircraft fleet to use MOGAS should be evaluated to assist both in assessing the potential value of the strategy as well as in designing the new refueling infrastructure. This evaluation can be performed in one of two ways: through an examination of the airport- based aircraft inventory, or through an examination of actual airport operations conducted by observation of aircraft tail numbers. The operations-based approach provides a more accurate reflection of facility activity but is more labor intensive. If an examination of the airport-based aircraft inventory is completed, the primary focus should be on the portion of the fleet used for commercial operations (e.g., flight schools), as the usage rates of these aircraft are significantly higher than for other aircraft. FAA databases of TCDSs (Type Certificate Date Sheets) and STCs (Supplemental Type Certificates) will provide information on the approved gasoline types for the identified aircraft. In either case, the data collected can be used to estimate the proportion of piston-engine aircraft suited for MOGAS consumption. Furthermore, the methodology as described in ACRP Report 133 and ACRP Web-Only Document 21 can estimate the proportion of AVGAS use that could be displaced by MOGAS. Another factor to be considered is whether incentives could be offered to specific aircraft or aircraft fleets, such as those operated by flight schools, to use MOGAS. Conversion to MOGAS, when possible, by aircraft that disproportionately contribute to lead emissions will increase the benefits of the MOGAS strategy. 6.1.3 Infrastructure Costs At most airports AVGAS is typically stored in double-walled underground tanks; however, aboveground tanks, which do not require excavation and any associated monitoring for leakage, may be less expensive options for making MOGAS available. Based on data available from other Source: www.airnav.com/fuel/report.html This report prepared by AirNav on 30-Mar-2016 Report includes prices reported between 02-Mar-2016 and 30-Mar-2016 At least 50% of prices are no more than 2 days old (28-Mar-2016 or more recent) FBOs 100LL Avgas FBOs Avg Min Max FUEL TYPES Jet A FBOs Avg Min Max Mogas (auto) FBOs Avg Min Max Nationwide 3668 3578 $4.61 $2.77 $9.58 2534 $3.98 $1.99 $8.25 117 $3.59 $2.25 $8.00 Alaska 76 67 $5.88 $4.63 $8.95 58 $5.44 $2.95 $8.25 4 $8.00 $8.00 $8.00 Central 356 354 $4.47 $2.99 $7.89 209 $3.57 $2.10 $7.30 18 $3.25 $2.48 $4.60 Eastern 366 352 $5.05 $3.34 $9.58 253 $4.49 $2.99 $8.15 7 $3.51 $2.98 $4.00 Great Lakes 745 734 $4.64 $3.06 $9.26 486 $3.90 $2.00 $7.36 47 $3.51 $2.63 $4.70 New England 143 137 $4.93 $3.30 $8.99 83 $4.40 $2.93 $7.95 5 $4.58 $4.05 $4.95 Northwest Mountain 387 379 $4.87 $3.00 $8.43 262 $3.98 $2.50 $6.78 14 $4.01 $3.13 $4.69 Southern 661 652 $4.39 $2.90 $8.99 522 $3.98 $2.25 $7.79 13 $3.53 $2.25 $4.52 Southwest 583 572 $4.23 $2.77 $8.33 410 $3.69 $1.99 $6.87 6 $3.43 $2.82 $4.25 Western-Pacific 351 331 $4.94 $3.14 $8.62 251 $4.30 $2.40 $7.88 3 $2.90 $2.90 $2.90 Figure 9. Fuel price report summary of fuel prices at 3,668 fixed base operators (FBOs) nationwide.
16 Guidebook for Assessing Airport Lead Impacts airport projects, the cost of installing infrastructure for storing about 5,000 gallons of MOGAS and dispensing it is approximately $100,000. There may, however, be additional costs required to address requirements of the National Envi- ronmental Policy Act (NEPA) and state laws related to modifications made to airport facilities. Such modifications are often required to be shown on the airportâs Airport Layout Plan, constituting a federal action requiring compliance with NEPA. If an airport makes modifications to its fueling facilities, FAA Orders 1050.1F and 5050.4B require compliance with NEPA, which may require the airport to perform other studies to support NEPA compliance. Given this, the actual environmental requirements as well as time and cost associated with compliance also need to be assessed. 6.1.4 Outreach and Review of Safety Protocols Consideration needs to be given to conducting public outreach to aviators, fixed base operators, and the local community. This outreach should address not only the availability and benefits of MOGAS, but also the safety hazards of misfueling aircraft that require AVGAS. 6.1.5 Future Availability of Unleaded AVGAS The MOGAS strategy would be rendered moot if 100 octane unleaded (100UL) AVGAS becomes available. As noted previously, the FAA is continuing to research the development of 100UL, with 2018 being the estimated timeframe for publishing ASTM specifications (FAA 2016b). However, publication of ASTM specifications does not mean commercial fuel produc- tion will immediately follow (for example, ASTM specifications for 82UL AVGAS were pub- lished in the late 1990s, and commercial fuel development has not yet commenced), and it is not clear at present what mechanisms, if any, would be employed to mandate use of the fuel. 6.2 Relocation of Run-Up Areas Piston-engine preflight run-ups can generate significant ground-level lead emissions. These operations occur in prescribed, confined run-up areas; have high emissions density (high emis- sions per unit surface area); and, depending on the characteristics of the airport, contribute significantly to peak lead concentrations. There are three primary options to reduce the peak lead concentration through managing run-up activities, as listed herein. ⢠Relocate the run-up location to increase the distance between run-up and takeoff operations (at the busiest runway), thereby reducing the likelihood of overlapping plumes of emissions. ⢠Use multiple run-up locations to serve the busiest runway, in effect redistributing run-up emissions to multiple locations and reducing the emissions density associated with run-up operations. ⢠Increase the size of the run-up area to increase capacity. This increases the surface area over which the emissions occur, potentially minimizing unnecessary idling that may otherwise occur due to traffic congestion. The primary focus of this strategy addresses the preflight run-up activities (i.e., the magneto test); a secondary focus is on engine maintenance run-up activities which should also be considered when developing an overall run-up management strategy for an airport. 6.2.1 Evaluation of Options As noted, there are three primary options to evaluate: run-up area relocation, run-up area activity redistribution, and run-up area expansion. The first step in implementation is to define each option and to determine all suitable candidate scenarios for further evaluation in subsequent air quality modeling.
Other Factors to Consider When Evaluating Potential Strategies to Reduce Lead Impacts at General Aviation Airports 17 Several assessments may be needed to completely characterize strategy options and define multiple candidate scenarios. Current conditions at the airport must be assessed (operations data, preflight run-up data, temporal distributions, and spatial distributions), as well as the meteorological data needed to calculate typical rolling 3-month period conditions (wind direc- tion, wind speed, total hours at stable conditions, etc.). Candidate areas suitable for a new run-up location need to be identified. Two forms of run-up area activity redistribution should be con- sidered: (1) if congestion is present, multiple run-up areas can be active simultaneously for a single runway; or (2) if congestion is not present, then run-up areas serving a single runway can be alternated. All options should be carefully considered to ensure that a substantial increase in taxi movements does not occur from adding or moving run-up sites, as this has the potential to offset the reduction(s) being sought. Time spent in run-up areas should be assessed to determine if congestion impacted the time spent in the run-up area and/or time spent waiting to enter the run-up area. Congestion levels should also be considered in determining whether larger run-up areas would be beneficial. From the assessments and data collection described herein, a set of strategy scenarios should be identified for the subsequent air quality analysis. Engineering judgment should be applied to determine if there could be changes in taxiing/idling times for a candidate scenario relative to current conditions. The time spent in taxi/idle mode may vary because of changes in travel distances, changes in congestion, and pilot instruction for the case of flight school operations. 6.2.2 Safety Considerations The primary safety concern is the interaction of this strategy with traffic control and manage- ment of aircraft movement. Adding complexity to aircraft movements around the airport may increase the potential for conflicts/collisions. In terms of safety, the simplest of the strategy sce- narios would be preferable. The simpler strategy options include (1) moving an existing run-up location to a new location; (2) alternating run-up locations based on the day of the week; and (3) increasing the size of run-up areas. More complex scenarios, such as the simultaneous use of multiple run-up areas, would require more pilot and traffic control interaction. 6.2.3 Noise Considerations Because run-up operations can be a significant source of noise for nearby residents, this strategy has the potential to affect noise planning efforts. Unexpected changes in the spatial distribution of noise at the facility may impact the facilityâs local surroundings and may also necessitate a review of the existing Federal Aviation Regulation Part 150 Airport Noise Compat- ibility Plan. The confounding influences of noise requirements may complicate implementation of this strategy. 6.2.4 Costs Based on a review of the literature, existing costs for run-up area relocation and/or construction were found to vary from about $100,000 to $500,000 depending on the size of the run-up area as well as the need for noise containment structures. 6.2.5 NEPA Consideration There are potential consequences under the NEPA and state laws related to modifications made to an airport layout. If an airport makes modifications to its fueling facilities, FAA Orders 1050.1F and 5050.4B require compliance with NEPA, which may require the airport to perform an Envi- ronmental Assessment or other studies. Given this, the actual environmental requirements, as well as time and cost associated with compliance, need to be assessed.
