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The electrical and mechanical failures (such as bearing and winding failures) combine to cause premature failures of the generators, which become a flight safety issue forcing the crew to land as soon as practical. Currently, diagnostic / prognostic technologies are not implemented for aircraft generators where repairs are time consuming and its costs are high. This paper presents the development of feature extraction and diagnostic algorithms to ultimately 1) differentiate between these failure modes and normal aircraft operational modes; and 2) determine the degree of damage of a generator. Electrical signature analysis based features were developed to distinguish between healthy and degraded generators while taking into account their operating conditions. The diagnostic algorithms were developed to have a high fault / high-hour detection rate along with a low false alarm rate.

Electrical and mechanical failures (such as bearing, winding and rotating-diode failures) combine to cause premature failures of the generators, which become a flight safety issue forcing the crew to land as soon as practical. Currently, diagnostic / prognostic technologies are not implemented for aircraft generators where repairs are time-consuming and costly. This paper presents the development of feature extraction and diagnostic algorithms to 1) differentiate between these failure modes and normal aircraft operational modes; and 2) determine the degree of damage of a generator. Electrical signature analysis (ESA) based time-domain features were developed to distinguish between healthy and degraded generators while taking into account their operating conditions. Frequency-domain based ESA techniques are used to identify the degraded components within the generators.

The two primary wire construction types being used in military aircraft today are cross-linked Ethylene Tetrafluoroethylene (XL-ETFE) and composite fluoropolymer / polyimide tape wrap with an outer Polytetrafluoroethylene (PTFE) tape wrap. These insulations offer significant improvements over earlier polyimide (MIL-DTL-81381) and polyvinyl chloride (PVC) constructions but are not without drawbacks. XL-ETFE provides a low smoke, high fluid resistant, non-arc tracking insulation that is durable during installation and ground repair operations. However, durability and abrasion resistance are reduced at elevated temperatures, and maximum operating temperature peaks at 200 degrees Celsius. Composite insulation provides a more abrasion resistant solution with the inclusion of polyimide tape for hard surface chafe conditions and a PTFE outer layer that improves wear life during wire to wire contact.

Two recent enhancements to Distributed Heterogeneous Simulation (DHS) are variable communication rates and higher-order predictors. Variable communication automatically controls the communication interval between any two subsystems in an attempt to achieve a desired accuracy during transient periods and maximize speed during steady-state periods. Higher-order predictors can better estimate the values of exchanged variables between data exchange instances, which can improve accuracy and possibly require fewer exchanges. A comparison between a single-computer simulation of an aircraft electric power system and an equivalent three-computer DHS show that the variable communication technique enables more accuracy and higher speed distributed simulations than fixed-step communication. In addition, higher-order predictors are shown to increase accuracy in some cases.

The use of Radio frequency identification (RFID) is increasing asset visibility, accountability and environmental assessment throughout industry. The application of RFID is maturing and expanding to include unforeseen uses. Asset accountability does not have to be constrained to identification alone. There is a myriad of opportunities if RFID technology infrastructure could support additional data beyond simple ID and tracking. Industry need has driven the development of enhanced RFID technology. Through the University of Arkansas' RFID Research Center, the discrete arenas of wireless and sensory technologies have merged and when coupled with internet applications are emerging to provide a viable integrated solution for capturing asset attribute data such as temperature and time. Specifically, the ability to monitor and control surroundings within a cold-temperature environment has been identified as a significant attribute from the consumer goods sectors.

In 1993, Grumman St. Augustine Corporation (GSAC) initiated a pollution prevention project to replace the methylene chloride based paint stripper that is currently used at the site. A total of eighteen different paint strippers were evaluated. Testing was conducted in the laboratory and field to ensure performance in an operational environment. Testing included: coating removal rates, sandwich corrosion, intergranular attack/end grain pitting and hydrogen embrittlement Stripping efficiency was evaluated on several different coating schemes: Epoxy Primer (MIL-P-23377TY1CL3) + Polyurethane Topcoat (MIL-C-83286), Epoxy Primer + Polysulfide (MIL-S-81733) + Polyurethane Topcoat, Epoxy Primer + Koroflex (TT-P-2760TY1CL2) + Polyurethane Topcoat.

The purpose of this study was to optimize the current design of the roll-on, roll-off sensor deployment system support arm for the C-130 Hercules. The Department of Defense (DOD) and the National Guard (NG) will be using these sensor pallet systems in a variety of command and control configurations for counter narco-terrorism applications along with several other applications. The original design for the sensor deployment arm will be drawn using CAD, and then a Finite Element Analysis will be modeled and analyzed using Pro/ENGINEER and Pro/MECHANICA. This will show the stress concentrations and the areas where weight can be saved. The most concerning variable will be the height of the mechanical arm attachment. By decreasing that height, and shortening the mechanical arm, the moments will decrease, and the required torque will be less.

Given the rapidly rising complexity of advanced-development aircraft and the diminishing experience pool of crewstation designers, a requirement exists for the implementation of crewstation development tools. These tools must support real-time simulation, advanced displays, and empirical data collection. Northrop’s Advanced Crewstation Integration Cockpit (ACIC) introduces full and rapid reconfigurability to a comprehensive aerodynamic, threat, sensor and weapons system simulation presented to the pilot on conventional or advanced-design displays. All controls and displays are reprogrammable, relocatable, and reconfigurable in their size, type of action and graphical attributes. Development capability for expert systems, sensor fusion, and data collection requirements are provided for. This standalone system, operating in real time, is unique in its ability to perform high-utility simulation at low cost.

Future more electric aircraft (MEA) architectures that improve electrical power system's (EPS's) source and load utilization will require advance stability analysis capabilities. Systems are becoming more complex with bidirectional flows from power regeneration, multiple sources per channel and higher peak to average power ratios. Unknown load profiles with large transients complicate common stability analysis techniques. Advancements in analysis are critical for providing useful feedback to the system integrator and designers of multi-source, multi-load power systems. Overall, a framework for evaluating stability with large displacement events has been developed. Within this framework, voltage transient bounds are obtained by identifying the worst case load profile. The results can be used by system designers or integrators to provide specifications or limits to suppliers. Subsystem suppliers can test and evaluate their design prior to integration and hardware development.

The electrical and mechanical failures (such as bearing and winding failures) combine to cause premature failures of the generators, which become a flight safety issue forcing the crew to land as soon as practical. Currently, diagnostic / prognostic technologies are not implemented for aircraft generators where repairs are time consuming and its costs are high. This paper presents the development of several algorithms to differentiate between these failure modes and normal aircraft operational modes, determine the degree of damage and remaining life of a generator. P-3 generator data (vibrations & phase voltages/currents) were collected for a seeded bearing failure involving lubrication defects in main bearing system. The results show that the frequency domain analysis of the generator's phase voltage can be used to detect its general health and impending bearing failures.