Aerospace and Electrical System Reliability
Yehia F. Khalil
Abstract
This research provides a reliability-based quantitative failure analysis of different architectural designs of the environmental control system (ECS) in commercial aircraft. The scope of analysis includes the two-, three-, and four-wheel ECS architectures. Reliability block diagrams (RBD) are developed ...
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This research provides a reliability-based quantitative failure analysis of different architectural designs of the environmental control system (ECS) in commercial aircraft. The scope of analysis includes the two-, three-, and four-wheel ECS architectures. Reliability block diagrams (RBD) are developed and quantified for the three architectures and quantified using recently published components failure rate data. Components contributions to the reliability of each of the modeled ECS architectures are calculated as well as their Birnbaum’s components importance measures. The results of this analysis show that the two-wheel architecture has a mean time between failure (MTBF) of » 21,438 hours, while the three-wheel architecture has an MTBF of » 14,050 hours, and the four-wheel architecture has an MTBF of » 13,634 hours. ECS reliability decreased by » 34.5% through adoption of the three-wheel architecture, and by 36.4% through adoption of the four-wheel architecture, as compared to the simple two-wheel ECS architecture. The calculated Birnbaum’s importance measures show that the most critical component in the two-wheel architecture is the cabin air circulation fan (CACF). For the three-wheel and four-wheel ECS architectures, the most important component is the condenser. The key contributions of this research are: 1) addressing current gap in the state of knowledge about ECS design life prediction and 2) providing insights into ECS reliability-based failure analysis.
Aerospace and Electrical System Reliability
Jalal Talebolhagh; Mehdi Mokhtari
Abstract
Lightning is a natural phenomenon when hits on a body causes multiple damages such as melting and burning at the point of contact, mechanical damage due to sound wave propagation and destruction due to magnetic flux. Lightning drains the electrical current up to 200 kA and the electro-thermodynamic reaction ...
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Lightning is a natural phenomenon when hits on a body causes multiple damages such as melting and burning at the point of contact, mechanical damage due to sound wave propagation and destruction due to magnetic flux. Lightning drains the electrical current up to 200 kA and the electro-thermodynamic reaction of the material may cause degradation, stratification, and surface breakdown. Most of the field observations of TV and FM towers’ collisions due to lightning strikes show that the main tubular columns have been severely ruptured in the vicinity of the foundation. The high temperature generated during the flow of electricity produces heat through the conductive structure of the main body of the tower, as well as the expansion of gas inside the pipe which ultimately results in the explosion of the pipe and rupturing the towers. In this paper, a part of a tubular column of the tower is chosen and analyzed in ABAQUS software under the effect of lightning induced heat flux. The results show that the very high heat flux generated at the tubular column of the tower could be the main reason for the fracture.
