Amber Berlin

The Clean Air Act, last amended in 1990, established a higher standard of environmental responsibility in the United States. In order to meet this standard, several initiatives were undertaken to reduce air emissions deemed harmful to human health. One such initiative was a close examination of the hazards presented by lead (Pb) fuel emissions. Pb fuel emissions are a by-product of the combustion of leaded gasoline in piston-engines, which are released into the air through the exhaust system. When airborne Pb is inhaled, it enters the bloodstream and raises the blood lead level (BLL) in the body. Because blood carries Pb through the entire body, it can result in widespread biological damage to cells and interruption of the cellular processes essential for cell survival.

Pb exposure is particularly dangerous to the brain because Pb has the ability to substitute for calcium ions and pass through the blood-brain-barrier (Sanders, Liu, Buchner & Tchounwou, 2009). Once in the brain, the toxic effects of Pb destroy healthy brain tissue and cause permanent damage in the central nervous system. According to Wu, Edwards, He, Zhen and Kleinman, (2010) substitution of Pb for calcium ions also affects the process of bone formation and remodeling, with Pb deposited in the bones in lieu of calcium and later released from bone tissue to recirculate in the body.

While it is known that large amounts of lead can be toxic, new research has shown that low-level lead exposure will also inhibit the brain’s ability to function. In a study on children, Miranda et al. (2007) show blood lead levels as low as 2 µg/dL (micrograms of lead in 100 ml of blood) have a significant impact on academic performance. This reduction in cognitive ability is identified as by The World Health Organization (2004) as “mild mental retardation resulting from loss of IQ points,” which has many negative effects on individuals and society as a whole (p.1495).

A loss of 2 IQ points has many social implications, such as moving an individual with a 71 IQ to below 70, an area considered mild mental retardation. While a drop in intelligence may affect the individual’s ability to perform academically, it also affects the way he or she is able to respond to the world. Individuals with limited intelligence tend to make less educated decisions than intelligent individuals, which may lead to fewer employment opportunities and various mistakes, even resulting in death. Furthermore, a self-awareness of having a below 70 IQ may create additional social problems because of a lack of confidence or self-esteem.

The monetary impact from a loss of 2 IQ points is substantial, with studies estimating the lifetime loss of income from the loss of IQ points ranges from $8,300 to $50,000/IQ point (Dockens, 2002; Pizzol, Thomsen, Frohn & Andersen, 2010). These losses extend beyond individual income and affect each member of society through our taxpayer dollars. An IQ below 70 qualifies children for special education classes and is also a qualifier for Social Security Disability benefits for intellectual disability (formerly known as mental retardation), which together cost nearly $8 billion a year.

While issues such as intellectual disability are apparent, the amount of toxic dust produced by Pb emissions often goes unnoticed. Pb dust is an invisible danger, settling on the surface of objects, vegetation, and into the top layers of soil. This dust is not easily removed from the environment, and according to Wu et al. (2010) Pb “does not appreciably dissolve, biodegrade, or decay and is not rapidly absorbed by plants” (p.309). The Pb in soil is a continuous hazard to small children because they absorb Pb more easily than adults and are more likely to ingest dirt. According to the World Health Organization (2010), an economic analysis revealed the cost of childhood lead poisoning to be $43 billion annually.

The Environmental Protection Agency (EPA) is the regulatory body charged with monitoring the national ambient air quality for Pb. After the identification of Pb fuel emissions as a health hazard, the EPA sought to reduce the amount of Pb in gasoline with the Clean Fuel Program in 1973. Highway use of leaded gasoline was finally prohibited in 1995.

In 2008, the EPA issued a final rule, lowering the National Ambient Air Quality Standard (NAAQS) from 1.5 µg/m3 (micrograms per cubic meter) to 0.15 µg/m3. The EPA acknowledged the acceptable risk of a loss of 2 IQ points, and used this as the measure to set the NAAQS for Pb (Chari, Burke, White & Fox, 2012). By 2012, the EPA had still not met the new standard and reported approximately 8.1 million people living in counties where Pb exceeds the NAAQS. The EPA also reported General Aviation (GA) is the leading contributor to Pb emissions through fossil fuel combustion in piston-engine aircraft, contributing an estimated 653 tons of airborne Pb annually (EPA, 2010).

Historically, General Aviation and GA aircraft have been exempt from a ban on leaded fuel because of its social and economic contribution. In 2005, General Aviation contributed $150.3 billion and over 1.2 million jobs to the U.S. economy (GAMA, 2006). Of the 3,300 airports open to the public and included in the FAA’s National Plan of Integrated Airport Systems (NPIAS), there are 2,952 landing facilities which depend on general aviation for community services such as aerial fire fighting support, aeromedical flights, agricultural support, aerial surveying, air cargo, disaster relief, remote population/island access, and U.S. Customs and border protection. GA links communities that would otherwise have no air support, providing vital services necessary for successful community development.

In 2010, piston-engine aircraft made up approximately 70% of the GA fleet, flying over 14.7 million hours. The majority of piston-engine aircraft use 100LL (Avgas), which may contain as much as 2.12 grams of Pb based fuel additive tetraethyllead (TEL) per gallon (EPA, 2008). The TEL additive boosts the octane rating and prevents early detonation of the fuel which may cause engine failure, but it is also the ignition of TEL that produces the Pb emission hazard.

While the entire population is affected by airborne Pb emissions, none is more affected than the population near airports. It is airports where Avgas is sold and used, where GA aircraft taxi and depart, and where the majority of Pb emissions are concentrated. A study on the impact of Avgas confirmed those living closest to the airport incur the greatest risks, including an estimated 16 million people living within 1km of an airport using Avgas, and 3 million children attend school within the same area (Miranda, Anthopolos & Hastings, 2011). The EPA also recognized their existing lead monitoring network is not sufficient to determine if all areas meet the new Pb NAAQS of 0.15 µg/m3.

The external costs of Pb emissions have been calculated at 41-83€/kg of emitted Pb (Pizzol et al., 2010), and for piston-engine aircraft, these external costs run approximately $37.5-$75.8 million per year.The health hazards and associated costs of Pb fuel emissions leave only one option for the GA fleet: stop using leaded fuel. In order to accomplish this task, GA has several options to consider, including renewable biofuel, fleet-wide modification, or to continue the search for a “drop-in” replacement that will meet or exceed the current engine specifications. Join us for the upcoming second part of this discussion as we discuss the future of GA fuel, including alternatives, and the FAA’s plan to phase out leaded avgas in Exploring Avgas Alternatives For General Aviation.

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References:

Chari, R., Burke, T. A., White, R. H. & Fox, M. A. (2012). Integrating Susceptibility into Environmental Policy: An Analysis of the National Ambient Air Quality Standard for Lead. Int J Environ Res Public Health., 9(4), 1077–1096. doi: 10.3390/ijerph9041077

Dockins C. (2002). Valuation of childhood risk reduction: the importance of age, risk preferences and perspective. In: Jenkins R, Owens N, Simon N, Wiggins L, editors. Risk Anal: Int J, 22(2), 335–46.

Environmental Protection Agency. (2008). EPA-420-R-08-020.

Environmental Protection Agency. (2010). Development and Evaluation of an Air Quality Modeling Approach from Piston Engine Aircraft Operating on Leaded Aviation Gasoline. EPA-420-R-10-007. http://www.epa.gov/nonroad/aviation/420r10007.pdf

General Aviation Manufactures Association. (2006). GA Contribution. Retrieved from https://www.gama.aero/files/ga_contribution_to_us_economy_pdf_498cd04885.pdf

Miranda, M. L., Kim, D., Galeano, M. A., Paul, C. J., Hull, A. P. & Morgan, S. P. (2007). The relationship between early childhood blood lead levels and performance on end-of-grade tests. Environ Health Perspect, 115(8), 1242-7.

Miranda, M. L., Anthopolos, R., & Hastings, D. (2011). A Geospatial Analysis of the Effects of Aviation Gasoline on Childhood Blood Lead Levels. Environ Health Perspect, 119(10), 1513–1516. doi: 10.1289/ehp.1003231.

Pizzol, M., Thomsen, M., Frohn, L. M. & Andersen, M. S. (2010). External costs of atmospheric Pb emissions: Valuation of neurotoxic impacts due to inhalation. Environmental Health, 9(9). doi: 10.1186/1476-069x-9-9.

Sanders, T., Liu, Y., Buchner, V., & Tchounwou, P. B. (2009). Neurotoxic Effects and Biomarkers of Lead Exposure: A Review. Review of Environmental Health, 24(1), 15-45.

World Health Organization. (2004). Comparative Quantification of Health Risks. Global and Regional Burden of Disease Attributable to Selected Major Risk Factors. Chapter 19, p. 1495. Retrieved from http://www.who.int/publications/cra/chapters/volume2/1495-1542.pdf

World Health Organization. (2010). Childhood Lead Poisoning. Retrieved from http://www.who.int/ceh/publications/leadguidance.pdf

Wu, J., Edwards, R., He, X. (E.), Zhen, L., & Kleinman, M. (2010). Spatial analysis of bioavailable soil lead concentrations in Los Angeles, California. Environmental Research, 110, 309–317.

^{Featured Image: Erik Brouwer}

Anders Clark

There are a vast amount of different types and models of general aviation aircraft from a variety of manufacturers. And there are a lot of interesting facts and information about these different aircraft.  Here are five lesser known facts from the world of general aviation aircraft that you will hopefully find as interesting as I did.

The Longest Continual In-Production General Aviation Aircraft

So, you’ve probably heard before that the Cessna 172 Skyhawk is the most produced aircraft of all time. However, though this is true, it’s not the general aviation aircraft with the longest continual production run. Delivery of the first of 172s started in 1956, but in 1986, Cessna was forced to stop production of all single engine aircraft for a decade due to the increasing cost of lawsuits and insurance. So, who’s the winner?

Buh bah duh buh bah duh buh bah duh buh, Bonanza! The Beechcraft Bonanza, that is. With the first Bonanza’s being delivered in 1947, the Bonanza has been in continual production for 69 years, making it the winner. During this time, more than 17,000 Bonanzas (including variants) have been produced, putting it a respectable 15^th on the all-time production list. Even more amazing, during the aforementioned period of hard times in the 80s and 90s that hit all aircraft manufacturers and stopped production of most other single engine aircraft, Beechcraft was able to keep the Bonanza (and their twin-engine Baron) in production.

The next closest competitor was the Russian-made Antonov AN-2, a single engine Biplane. The AN-2 started production in the same year, 1947, as the Bonanza. However, production stopped in 2001, after 54 years. China started building variants of this aircraft around that time, which some think keeps the streak alive, but in the case of a tie, I figure the Bonanza gets the win with the clearer claim.

The First Airplane Manufacturer

Speaking of aircraft manufacturers, who was the world’s first to start making production aircraft? You may expect a name like Cessna, Boeing, or Piper to pop up, but it was actually some brothers. No, not those brothers (though they weren’t far behind), but rather the Irish Short brothers, Eustace, Oswald and Horace. The Short Brothers actually started their business in 1897, to manufacture baloons. However, in 1908, after hearing reports from the Royal Aero Club of the Wright Brothers demonstration of their aircraft in Le Mans, they shifted gears towards production of airplanes. By November of 1908, the three borthers had registered their partnership under the name Short Brothers and were ready to start taking airplane orders.

Their first two orders came from Charles Rolls (one of the co-founders of Rolls-Royce) and Francis McClean, a founding member of the Aero Club and repeat customer who would also act as a test pilot for the Short Brothers. So they set to work on a pair of designs, and exhibited McClean’s aircraft, the Short No. 1 Biplane, in March 1909 at the British Aero Show. They also were able to obtain the British rights to manufacture aircraft based on the design by the Wright Brothers.

Short Brothers is still around today though it was acquired in 1989 by Canadian aerospace giant Bombardier. In addition to making aircraft components, engine components and flight control systems for Bombardier, they also provide these services to Boeing, Rolls-Royce, General Electric and Pratt and Whitney. Not bad for a trio of brothers a little more than a century ago.

OK, So What Was the First Mass-Produced General Aviation Aircraft?

Well, there appear to be two candidates for this honor, the Wright Model B, and the Bleriot XI. After achieving sustained, powered flight with the Wright Flyer 1 in 1903, the Wright Brothers developed a series of additional models, including the Wright Flyer III which is considered their first practical model, and was their first to carry a passenger. By 1910 (a busy year in which they were also establishing the first flight school), they arrived at the Wright Model B. Built and sold by the newly formed Wright Company, this was their first mass produced general aviation aircraft. From 1910 – 1914, they built an estimated 100 of these aircraft, with four of them going out a month at the height of production. Despite the number built, only one original Wright Model B survives fully intact, and it’s currently displayed in the Franklin Institute in Philadelphia, Pennsylvania. There is a second Wright Model B on display at the United States Museum of the Air Force in Dayton, Ohio, but it appears to have been manufactured after the original production run. Orville Wright is said to have inspected the airplane when it was displayed at the 1924 International Air Races, and called it a “mongrel.” Harsh, man.

Meanwhile, during this same time, Louis Bleriot was making waves over in Europe, after becoming the first person to successfully fly across the English Channel. He achieved this feat on July 25^th, 1909, in his Bleriot XI. After the flight, demand for this aircraft took off (bah dum CHH) and by September 1909, Bleriot had received 103 orders for this aircraft. They started building, and production continued until the outbreak of World War I. Two of these aircraft have been restored to airworthy condition, one in the UK and one in the US, and they are thought to be the two oldest flyable aircraft in the world.

The Highest Fixed-Wing Landing Ever

So, there are some high altitude airports out there, with the recently opened Daocheng Yading Airport in China being the highest, at 14,472 feet (4,411 m). However, the highest landing by a fixed-wing aircraft ever is still thousands of feet above this. In April 1960, a prototype of the Pilatus PC-6 Porter, nicknamed “Yeti,” was landed on the Dhaulagiri Glacier at an altitude of 18,865 feet (5,750 m). The Porter, well know for it’s STOL capabilities, was described by Flying magazine as being “one of the most helicopter-like airplanes in terms of takeoff performance.”

And if that wasn’t enough street cred for one plane, the Porter also holds the record for the most take offs and landing in a 24 hour period, set while helping Skydiver Michael Zang achieve his goal of 500 skydives in a 24 hour period. Takeoff, reach 2,100 feet, Zang jumps, land, pick up Zang, and repeat. 500 times. The average length of each of these cycles was roughly 2 minutes and 45 seconds. Also, the Porter pilot Tom Bishop holds a record for the most consecutive takeoffs and landings with 424 over a 21 hour period.

Speaking of High Altitudes

The highest altitude obtained by a piston engine, propeller driven airplane is 60,866 feet. This was achieved in 1995 by a Grob Strato 2C, a twin-engine experimental aircraft specially designed for high altitude flight.

So, how about the single piston engine, propeller driven airplane altitude record? That would be 56,047 feet (17,083 m), a record set by Italian pilot Mario Pezzi. But here’s the truly incredible thing: Prezzi set this record on October 22^nd, 1938, and the record still stands today. He set it in a Caproni Ca. 161 Biplane, with a pressurized, airtight cabin, and wearing a special pressure suit.

In Conclusion

These achievements and stories regarding general aviation aircraft reflect only a fraction of the ingenuity and achievements attained during the history of aviation. They represent a monumental push onward and upward, one that is joined and continued every day by scientists, engineers, pilots, and adventurers. I think the early pioneers of flight would be astounded by just how far we’ve come. Here’s to seeing how far we can go.

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