Thesis (M.S.)--Auburn University, 2007. / Abstract. Vita. Includes bibliographic references (ℓ. 91-98)

The use of only one primary sort of energy is the present trend of aircraft design and its force systens. There are designed electromagnetical force systems for control of ther moving parts of aircraft structure. Great demands are laid on energy and dynamic characteristics at some force systems, especially at aircraft control system, and therefore there are developed electro-hydrostatic actuators, suitable for aircraft for aircraft control system, which could graduallly replace commonly used hydraulic servo-controol system. Not only electric signals but also required electric outputs are led into these electro-hydraulic actuators. Using a hydrostatic converter it is changed into mechanical output controlling the aircraft control system. The goal of work is to set requirements for characteristic and conception of electro – hydrostatic actuators for aircraft control systems. Further, on the basis of theoretical analysis , computer modeling and experiment, the design optimisation of electro-ghydrostatic actuator should be done for small business aircraft from the point of view of dimmensions and dynamic characteristics.

<p>General Aviation (GA) is a category of aircraft operations, exclusive of all military and commercial operations. According to Federal Aviation Administration (FAA), fixed-wing aircraft (also known as airplanes) account for 76.2% of all the estimated registered GA fleet in the United States. Out of all the GA accidents that the National Transportation Safety Board (NTSB) investigated in 2017, 87.7% of the accidents involved fixed-wing aircraft. The NTSB reports on all GA accidents and records the accident details in their database. The NTSB database has an abundance of accident data, but the data is not always logically complete and has missing information. Many researchers have conducted several studies to provide GA fixed-wing accident causation using the NTSB accident data. The quantitative analyses conducted by the researchers focused on a chain of events approach and identified the most frequent events in accidents. However, these studies provided little insight into why the events in the accidents happened. In contrast, the qualitative analyses conducted an in-depth study of limited accidents from the NTSB database. This approach helps in providing new findings but is difficult to apply to large scale datasets. Therefore, our understanding of GA fixed-wing accident causation is limited. This research uses a state-based approach, developed by Rao (2016), to provide a potentially better understanding of causes for GA fixed-wing accidents. I analyzed 10,500 fixed-wing accidents in 1982–2017 that involved inflight loss of control (LOC-I) using the state-based approach. I investigated the causes of LOC-I using both a conventional approach and a state-based approach. I analyzed fatal, non-fatal and overall LOC-I accidents in three timeframes: 1989–1998, 1999–2008 and 2008–2017. This multi-year analysis helped in discerning changes in the causation trends in the last three decades. A mapping of the LOC-I state definition to the NTSB codes helped in identifying 2350 more accidents in the database that were not discernible using the conventional approach. The conventional analysis revealed “directional control not maintained” as the top cause for the LOC-I accidents, which provides little information about how loss of control happened in accidents. The state-based analysis highlighted some important findings that contribute to LOC-I accidents that were not discernible using the conventional approach. The state-based analysis identified preflight mechanical issue as one of the new causes for LOC-I with a presence in 5.1% of LOC-I accidents in 2009–2017. It also helped in inferring some of the missing information in the accident data by modeling the accidents in a logical order. Using the logic rules in the state-based approach, I inferred that the pilot’s tendency to hit objects or terrain caused loss of control in 19.9% of LOC-I accidents in 2009–2017. Further, the logic rules helped in inferring that 7.5% of LOC-I accidents in 2009–2017 involved hazardous condition of an aircraft before the start of flight. A comparison of the findings from state-based approach with the GAJSC (General Aviation Joint Steering Committee) safety enhancements revealed that the state-based approach encompassed all the potential issues addressed in the safety enhancements. Additionally, a state-based analyses of larger datasets of fatal and non-fatal accidents suggested some new potential issues (such as improper maintenance) that were not explicitly addressed in the GAJSC safety enhancements. </p>

Synthetic Vision is an aviation technology that uses databases and position estimation to establish a view of the database which provides an intuitive view that corresponds to the features of the outside world. The Synthetic Flight Bag is a low cost, portable system which implements synthetic vision, moving map, and route planning in a single software and hardware package. Human factors analysis was performed to identify appropriate functional requirements for the development of the system. Preliminary simulator testing identified requirements on screen size and mounting location with a mind to the cramped general aviation cockpit. Hardware survey identified appropriate computing platform targets. Hardware selected was a compact motherboard intended for embedded systems applications and graphics support. It was packaged into a custom-built avionics case, along with supporting power and I/O hardware. An LCD display with touch screen was designed and built, and represents the smallest, yet highest resolution display commercially available at this time. Software development led to a complete system with a primary flight display, multi function display, vertical profile display, and a menu and information system allowing for flight plan editing. A flight test aircraft was instrumented and outfitted with the Synthetic Flight Bag system. A ground simulator was also created for the purpose of training prior to flight test. VFR and IFR pilots participated in the study, and were evaluated on flight technical errors, workload, and eye movement. A flight test was performed, and results indicated that while the Synthetic Flight Bag system improves terrain awareness, it is not in its tested version a complete solution to the problem. The system was found to significantly improve the accuracy of flight, but was also found to increase workload in pilots not yet familiar with its operation. Several future improvements were identified, but the system as designed meets the project needs.

General aviation in the United States has been an important part of the economy and American life. General aviation is defined as all flying excluding military and scheduled airline operations, and is utilized in many areas of our society. The majority of aircraft operations and airports in the United States are categorized as general aviation, and general aviation contributes more than one percent to the United States gross domestic product each year. Despite the many benefits of general aviation, the lead emissions from aviation gasoline consumption are of great concern. General aviation emits over half the lead emissions in the United States or over 630 tons in 2005. The other significant negative externality attributed to general aviation usage is aircraft accidents. General aviation accidents have caused over 8000 fatalities over the period 1994 - 2006. A recent Federal Aviation Administration proposed increase in the aviation gasoline tax from 19.4 to 70.1 cents per gallon has renewed interest in better understanding the implications of such a tax increase as well as the possible optimal rate of taxation. Few studies have examined aviation fuel elasticities and all have failed to study general aviation fuel elasticities. Chapter one fills that gap and examines the elasticity of aviation gasoline consumption in United States general aviation. Utilizing aggregate time series and dynamic panel data, the price and income elasticities of demand are estimated. The price elasticity of demand for aviation gasoline is estimated to range from -0.093 to -0.185 in the short-run and from -0.132 to -0.303 in the long-run. These results prove to be similar in magnitude to automobile gasoline elasticities and therefore tax policies could more closely mirror those of automobile tax policies. The second chapter examines the costs associated with general aviation accidents. Given the large number of general aviation operations as well as the large number of fatalities and injuries attributed to general aviation accidents in the United States, understanding the costs to society is of great importance. This chapter estimates the direct and indirect costs associated with general aviation accidents in the United States. The indirect costs are estimated via the human capital approach in addition to the willingness-to-pay approach. The average annual accident costs attributed to general aviation are found to be $2.32 billion and $3.81 billion (2006 US$) utilizing the human capital approach and willingness-to-pay approach, respectively. These values appear to be fairly robust when subjected to a sensitivity analysis. These costs highlight the large societal benefits from accident and fatality reduction. The final chapter derives a second-best optimal aviation gasoline tax developed from previous general equilibrium frameworks. This optimal tax reflects both the lead pollution and accident externalities, as well as the balance between excise taxes and labor taxes to finance government spending. The calculated optimal tax rate is $4.07 per gallon, which is over 20 times greater than the current tax rate and 5 times greater than the Federal Aviation Administration proposed tax rate. The calculated optimal tax rate is also over 3 times greater than automobile gasoline optimal tax rates calculated by previous studies. The Pigovian component is $1.36, and we observe that the accident externality is taxed more severely than the pollution externality. The largest component of the optimal tax rate is the Ramsey component. At $2.70, the Ramsey component reflects the ability of the government to raise revenue aviation gasoline which is price inelastic. The calculated optimal tax is estimated to reduce lead emissions by over 10 percent and reduce accidents by 20 percent. Although unlikely to be adopted by policy makers, the optimal tax benefits are apparent and it sheds light on the need to reduce these negative externalities via policy changes.

The General Aviation Airport Choice model is an attempt to model General Aviation (GA) travel patterns in the US in order to provide a means of assessing the impact of General Aviation activities on the National Air Space system. The model will also serve as part of transportation planning tool to help assess the viability of deploying NASA's Small Aircraft Transportation Systems (SATS) aircraft as a competitive mode of transportation for intercity travel. The General Aviation Airport Choice model developed estimates General Aviation (GA) person-trips and number of aircraft operations given trip demand in the form of GA person trips from counties. A pseudo-gravity model is embedded in the model to distribute the inter-county person-trips to a prescribed set of airports in the US. The airport-to-airport person-trips are split into person-trips by three aircraft modes (single, multi and jet engine) using an attractiveness factor based on average occupancy, utilization and a distance distribution factor for each aircraft type and the number of aircraft based at each airport. The person-trips by aircraft type are then converted to aircraft operations using occupancy factors for each aircraft type. The final output from the model are aircraft operations trip-tables by aircraft type between the airports in the model. The GA trips are estimated in order to provide a means of assessing the impact of GA activities on the National Airspace System. The model output may be used to assess the viability of GA aircraft serving as a competitive mode of transportation for intercity travel. / Master of Science

The replacement of lead additives in aviation fuels with non-leaded alternatives is of great interest to the aviation community. Ethanol, which may be derived from renewable resources, has been suggested as an octane-enhancing additive for general aviation fuel. Besides the consideration of the additive?s performance in meeting the requirements of aircraft engine combustion characteristics, there is also a concern about the material compatibility of ethanol fuels with respect to fuel system components consisting of metallic and polymer materials. This research project focuses on the effects of ethanol based fuels on the corrosion of metal components in fuel systems of general aviation aircraft. The types of metals that are studied include aluminum, brass and steel. Blends of gasoline that were tested were mixed with 10% to 85% ethanol by volume. The potential for corrosion to occur was determined through conventional weight loss methods and electrochemical measurements. By applying the principles of kinetics to the electrochemical reaction, the rate of corrosion was determined. Potentiodynamic polarization electrochemical techniques were used to determine the corrosion rates of metals exposed to various ethanol based fuels. Tafel extrapolation and linear polarization were correlated to corrosion rates. Impurities of water, chloride ion, and hydrogen ion were studied for their effect on the corrosion rate. Planned-interval tests were performed to investigate the change of the corrosive characteristics of metal and the change of the corrosiveness of the ethanol based fuels. Finally, DCI-11 from Octel-Starreon, was chosen to study the mechanism of commercial corrosion inhibitors. An observation was made that ethanol based fuels can create corrosion problems to some metal aircraft components. The inhibitor tested was effective in protection for fuel containing high percentages of ethanol. A correlation has been developed between observed metallic corrosion and fuel conductivity. The use of a corrosion inhibitor, conductivity measurements, and non-destructive component inspections should be incorporated in any future regulations intended to approve the use of ethanol based fuels in the existing fleet of general aviation aircraft.

This research examined human-machine performance in a General Aviation (GA) environment under dynamic conditions using a combination of field study and laboratory experimentation. Using this combination of methods, the functional system of pilots performing a landing approach (both instrument and visual) with a Cessna 172 to the Roanoke Regional Airport (ROA) was described and analyzed. In the field study, data collection was guided by an integrative method based on macroergonomics (ME) and distributed cognition (DC), allowing the cognitive aspects of a sociotechnical system to be treated as equally important as the organizational components. Also of interest was how pilot performance was affected by the introduction of nighttime and deteriorating weather conditions to this GA environment. Few statistically significant differences were found between pilots who flew by visual flight rules (VFR) and those who flew by instrument flight rules (IFR) or within each of these pilot groups in terms of objective flight performance. However, there were several significant differences between VFR and IFR pilots and within each pilot group in terms of workload and especially situation awareness across conditions; situation awareness for VFR pilots was found to be significantly reduced compared to situation awareness for IFR pilots in nighttime and deteriorating weather conditions (p < 0.05). In addition to these statistical findings and the methodological contribution of a joint systems/cognitive method, contributions of this dissertation include a greater understanding of the GA pilot/cockpit system and a systems-oriented cognitive model of this aviation environment as described by the ME/DC method for both VFR and IFR pilots. Further, procedural comparisons were performed between the flight simulator and the actual Cessna 172 used in the field study to increase our understanding of how to improve the validity associated with using simulators in research. Findings from both the laboratory and field studies in this research support new designs and technologies envisioned for future aviation systems that would assist the pilot during a landing approach such as weather information systems, head-up displays, synthetic vision, three-dimensional auditory displays, increased automation, and communications filters. Potential future applications of this research are also explored. / Ph. D.

Doctor of Philosophy / Department of Psychology / Richard J. Harris / Systems that support or require human interaction are generally easier to learn, use, and remember when their organization is consistent with the user’s knowledge and experiences (Norman, 1983; Roske-Hofstrand & Paap, 1986). Thus, in order for interface designers to truly design for the user, they must first have a way of deriving a representation of what the user knows about the domain of interest. The current study evaluated three techniques for eliciting knowledge structures for how General Aviation pilots think about weather information. Weather was chosen because of its varying implications for pilots of different levels of experience. Two elicitation techniques (Relationship Judgment and Card Sort) asked pilots to explicitly consider the relationship between 15 weather-related information concepts. The third technique, Prime Recognition Task, used response times and priming to implicitly reflect the strength of relationship between concepts in semantic memory. Techniques were evaluated in terms of pilot performance, conceptual structure validity, and required resources for employment. Validity was assessed in terms of the extent to which each technique identified differences in organization of weather information among pilots of different experience levels. Multidimensional scaling was used to transform proximity data collected by each technique into conceptual structures representing the relationship between concepts. Results indicated that Card Sort was the technique that most consistently tapped into knowledge structure affected by experience. Only conceptual structures based on Card Sort data were able to be used to both discriminate between pilots of different experience levels and accurately classify experienced pilots as “experienced”. Additionally, Card Sort was the most efficient and effective technique to employ in terms of preparation time, time on task, flexibility, and face validity. The Card Sort provided opportunities for deliberation, revision, and visual feedback that allowed the pilots to engage in a deeper level of processing at which experience may play a stronger role. Relationship Judgment and Prime Recognition Task characteristics (e.g., time pressure, independent judgments) may have motivated pilots to rely on a more shallow or text-based level of processing (i.e., general semantic meaning) that is less affected by experience. Implications for menu structure design and assessment are discussed.

<p>General Aviation (GA) is the foundation of most flying activities and the training ground for civilian pilots, both recreational and professional. However, the safety record for GA is lacking compared to that of commercial aviation. Approximately 75% of accidents each year involve personnel factors, that is, even if the pilot was not the cause of the accident, they could have done something to either prevent it or improve the outcome.<br></p> <p> </p> <p>In this research, I aim to improve GA safety through safety-driven post-flight debrief that encourages pilots to consider the risk in their flights and identify behavioral changes that could make their flying safer. Providing pilots with a debrief tool that they can use with or without a flight instructor requires that we know both what to communicate, and how to communicate it. Risk communication heuristics and biases have not been researched in the context of aviation and flight training and we therefore do not know how pilots understand or respond to debrief.</p> <p> </p> <p>To achieve the goals of this work, I used a three-step process: (1) identify events that may put the safe outcome of a flight at risk, (2) detect those events in flight data, and (3) inform the pilot in a way that helps them improve in their future flights. I use a state-based representation of historical aviation accidents to define a list of events or behaviors that need to be communicated to the pilots, in the form of states and triggers. I use flight data to retrospectively detect these behaviors upon completion of the flight, by mapping parameters or combinations of parameters that can be calculated and tracked in the flight data to the hazardous states and triggers defined. To present these events to pilots, I created a prototype interactive debrief tool with risk information that I use in a survey to evaluate the effectiveness of feedback in different representation formats. Specifically, I evaluate the impact of three factors: representation method (graphical and numerical), parameter type (safety and performance parameters), and framing language (risk-centric and safety-centric). </p> <p> </p> <p>I disseminated the survey via aviation mailing lists, type groups, flying clubs, and flight training providers, end received 268 responses. The survey analysis showed that the feedback representation does affect its effectiveness in terms of risk perception, but not when it comes to pilots’ motivation to change. The lessons learnt from this survey can be used in creating additional surveys that delve further into risk communication biases and our understanding of how pilots perceive risk and feedback.</p>