Life Cycle Analysis of Aircraft Environmental Control Systems - Essay Example

Life cycle analysis of the environmental control systems (ECS) is a significant part of the aircraft functioning during flights. In this respect a particular analysis of ECS in terms of design and manufacture, installation on the aircraft, removal for repair at the depot level, and complete replacement from the manufacturer. Thus, the first steps in analysis touch upon the structure and determination of ECS for airframes. Then, it is vital to point out the focal meaning of operating systems and their use for the normal work of civilian airframes, such as Boeing 747 and Airbus A-380. All in all, to delve into the full life cycle analysis of ECS means to incorporate a constructive approach toward estimation of the full life cycle and its applicability as one of the most sign significant subsystems throughout an aircraft. First and foremost, air-conditioning and air-pressurization vary in accordance with the compressor stage at the moment. In this respect different climate factors impact the way the “bleed air” comes in the aircraft during the flight. In this respect the design for usability is taken to make out the functional specificity of all control subsystems in the airframe. That is to say, the relationship between operational requirements maintenance concept, functional analysis and requirements allocation as well as environmental considerations (economical, ecological, political, societal, and technological) points out the full life cycle of the aircraft in its vital control systems (Blanchard & Fabrycky, 2011). Thus, the stage of design and manufacture of ECS sparks interest first. Martinez (2011) draws upon the relationship between ECS and environmental protection systems (EPS) so as to justify the need for an accurate installation of both systems. It is a substantial warrant of security and operational stability of the aircraft. Moreover, ECS design should comply with widely differing temperatures depending on the geographical and atmospheric variety of temperatures, pressures, humidity and the like. Thereupon, a ste of factors, such as kinetic and solar heating, avionics heat loads, airframe system heat loads, the need for cabin conditioning, are to be taken into account by manufacturers (Moir & Seabridge, 2008). It is a predominant to calculate air-cycle process inside the cabin and regarding to the outer factors mentioned above. Figure 1. Air flow inside an aircraft cabin. Recirculation system is, perhaps, one of the main parts of ECS as it is designed with filters having no bypass and controlling gases to low levels due to “high quantities of outside airflow per cubic volume of space” (Hunt, Reid, Space, & Tilton, 2009, p. 5). This is why when installing a specifically designed ECS, the recirculation filters and fans should be checked out precisely. However, on the level of 30,000 feet or more, the pressure factor should also be taken into consideration. It is all about the automatically set outflow valves used to maintain the desired cabin pressure (National Research Council (U.S.); Committee on Air Quality in Passenger Cabins of Commercial Aircraft, 2002). Thus, the life cycle cost depends on the way ECS was used and how it operated throughout the period of direct functioning. In this respect anti-ice system and the recirculation system are the main precursors for further worn-out state of ECS. The thing is that modern ECS re-circulates “up to half of the cabin air…and whilst the ECS fresh air is treated to remove ozone, the recycled cabin air is filtered for many unwanted contaminants, including: 1) micro-organisms; 2) dust; odors; VOC’s” (Seabridge & Morgan, 2010, p. 36). ECS differ in terms of their practical endurance and workability in different outer environments. Based on the example of aircraft Airbus A-380 with its double-deck widebody passenger airliner, the significance of air conditioning grows as the inner space is considered the largest in this huge aircraft. Called an air jumbo in aviation, this airliner has one of the most powerful ECS’s at its disposal. The question is that the A3XX ECS used in A-380 has two double-packs with four air cycle machines and with four stages in each which are 85 percent more powerful than any previous version (Norris & Wagner, 2010). By decreasing the size of the system and decreasing its efficiency the period of ECS exploitation has grown for Airbus and A-380, in particular. The issue of aircraft life cycle as concerned with ECS is that it is reliable but too expensive (1 kW/pax) for airlines based on the example of the two most popular aircrafts (Airbus and Boeing) (Martinez, 2011). Repairing ECS’s on the depot level, the experts constantly face with the heat-exchangers and an extreme change of ram air outlets and inlets. This procedure is costly, but contemporary avionics has yet nothing to do with that. Figure 2. ECS heat-exchanger layout (typical size of each HE is 70.7·0.5·0.3 m3, and 10..15 kg) Hence, by means of a close analysis of ECS, it is vital to keep up with the performance/inspection scheduling early in the design and selection phase for this important subsystem. Thus, the evidences of repair and complete replacement are often. Even though the full life cycle of ECS is supposed to be 5-10 years and usually duplicated or triplicated for safety on modern aircrafts, the period of exploitation requires much efforts in finance and maintenance (Fielding, 1999). Thus, it is all about the variety of subsystems incorporated in ECS. In this vein, Boeing and Airbus are distinguished in following different trends: AIRBUS. For its new born aircraft the A350 XWB, Airbus decided to keep on implementing an engine bleed air driven ECS but combined with advanced engines, the GE GEnx-1A and the RR Trent 1700. BOEING. For its new aircraft, the twin-engine 300 seat B787, Boeing has moved to an all electric ECS (AE-ECS), eliminating any engine bleed (Martinez, 2011, p. 5). These implications state on more electrically-driven suggestions and decisions worked out for contemporary passenger aviation. Pressurization, humidity control, and temperature levels are to be weighed on their relation to other vital flight control systems (FCS). There is an accurate suggestion that “it may be necessary to remove heat from the undercarriage bays, electrical equipment and flying control areas” (Fielding, 1999, p. 74). It is important to make sure there is no threat for the rest of control systems throughout an aircraft on the part of ECS. Once again, it is necessary to bear it in mind that bleed-air supply has two detrimental factors, namely: high pressure and high temperature before bypasses. Thus, the use of pre-coolers is significant after the bleed air with an approximate pressure of 1,170 kPa is extracted from the engine and reduced to 310kPa by pressure regulators (National Research Council (U.S.); Committee on Air Quality in Passenger Cabins of Commercial Aircraft, 2002). Thus, anti-ice systems have to be more efficient in technical functionality. Overall, the life cycle of ECS presupposes the workload of all of its parts and subsystems in terms of functionality and resistance to physical impacts during the flight and while staying at different localities. In this respect the Annual Operating Cost is expressed through the following formula: OC = (EC + LC + PMC + other)N Where EC = annual cost of energy consumed LC = annual cost of operating labor PMC = annual cost of preventive maintenance N = the number of deployed equipment units (Blanchard & Fabrycky, 2011, p. 621). In this respect ECS has to be checked every now and then for its cost-efficiency. Otherwise, there is a problem of high expenditures nevertheless the period of exploitation has not passed yet. Thus, the need for storage springs up eventually. Talking about passenger aircrafts based on the examples of Boeing and Airbus, there are two basic kinds of storage: “temporary storage (storage of products that support short-term replenishment activities) and long-term storage (storage of products in excess of the requirement for normal replenishment in order to build up a buffer or safety stock)” (Blanchard & Fabrycky, 2011, p. 513). These pre-caution measures are vital for regular flights and for supersonic aviation with rare flights in hand. Thus, the life cycle of aircraft ECS depends on the characteristic features of the system itself opposite to the physical and health factors. In this case the use of air control machines, air-conditioning systems, and pressure regulators has to be accomplished with the specific norms and standards of exploitation before, during, and after each flight. With a particular period of the full life cycle in hand, there are different detrimental factors (piping hot and highly-pressured air through ram outlets, filters and fans) which cannot be predicted in a distinctive proportion of time and place where it is about to happen. Thus, aircraft companies such as Boeing and Airbus seek to refuse from solely mechanical ECS’s by changing then into more distributed and electrically-driven systems (Martinez, 2011). Definitely, this trend is applicable for contemporary aviation. With different sources of environmental stimuli, the airborne uninhabited environment should not represent a danger for the airborne inhabited environment (Seabridge & Morgan, 2010). Thus, the issue of aircraft ECS has to be pursued in development. Reference Blanchard, B. S., & Fabrycky, W. J. (2011). Systems Engineering and Analysis (5 ed.). Upper Saddle River, NJ: Prentice Hall. Fielding, J. P. (1999). Introduction to aircraft design. Cambridge: Cambridge University Press. Hunt, E. H., Reid, D. H., Space, D. R., & Tilton, F. E. (2009). Commercial Airliner Environmental Control System: Engineering Aspects of Cabin Air Quality. Retrieved June 29, 2011, from Boeing: http://www.boeing.com/commercial/cabinair/ecs.pdf Martinez, I. (2011). Aircraft Environmental Control. Retrieved June 29, 2011, from UPM: http://webserver.dmt.upm.es/~isidoro/tc3/Aircraft%20ECS.htm#_Toc233109834 Moir, I., & Seabridge, A. (2008). Aircraft systems: mechanical, electrical, and avionics subsystems integration (3 ed.). Hoboken, NJ: John Wiley and Sons. National Research Council (U.S.); Committee on Air Quality in Passenger Cabins of Commercial Aircraft. (2002). The airliner cabin environment and the health of passengers and crew. Washington, DC: National Academies Press. Norris, G., & Wagner, M. (2010). Airbus A380: Superjumbo of the 21st Century. Washington, DC: Zenith Imprint. Seabridge, A., & Morgan, S. (2010). Air Travel and Health: A Systems Perspective. Hoboken, NJ: John Wiley and Sons. Read More