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Technical Paper

A Market Perspective on FANS

The implementation of the Future Air Navigation System (FANS) will be evolutionary rather than revolutionary. Different generations of airplane models, each operating in a variety of operating environments will dictate more than a single growth path. How these markets will evolve is a function of our collective ability to assign benefits to specific equipage, to forge new business relationships and to address the market as a global one. Realization of the full benefits of FANS will depend on leadership: who and when.
Technical Paper

Heat Exchanger Fouling Detection in Aircraft Environmental Control Systems

The operating environment of aircraft causes accumulation and build-up of contamination on both the narrowest passages of the ECS (Environmental Control System) i.e: the heat exchangers. Accumulated contamination may lead to reduction of performance over time, and in some case to failures causing AOG (Aircraft on Ground), customer dissatisfaction and elevated repair costs. Airframers/airlines eschew fixed maintenance cleaning intervals because of the high cost of removing and cleaning these devices preferring instead to rely on on-condition maintenance. In addition, on-wing cleaning is t impractical because of installation constrains. Hence, it is desirable to have a contamination monitoring that could alert the maintenance crew in advance to prepare and minimize disruption when contamination levels exceed acceptable thresholds. Two methods are proposed to achieve this task, The effectiveness of these methods are demonstrated using analytical and computational tools.
Technical Paper

Inerting Aircraft Fuel Tanks - Reducing the Hazard

Aircraft accidents caused by explosion of the vapor within the fuel tanks have been the subject of many recent articles. Methods of either suppressing the combustion or preventing the ignition have been considered. Indeed, solutions such as liquid nitrogen, halon, and reticulated foam have been installed on production aircraft. However, these have proved to be expensive to operate or are being phased out. By working together, the authors have developed the capability to provide fully integrated On-Board Inert Gas Generating Systems (OBIGGS) based on novel hollow fiber membrane technology. An overview of the advantages of such an approach is presented together with an outline of the system design method. The importance of considering the effect of differing flight profiles, and the inter-reactions of the OBIGGS, with the Fuel System, Engine Bleed Air Management, and Environmental Control Systems in the design process are emphasized.
Technical Paper

Reliable Bearing Wear Detection System for On-Condition Maintenance of Electric Generators

Demand on the reliability of Electric Generators for Aerospace applications is assuming more importance everyday with the advent of “Fly-by-Wire” and “More-Electric-Aircraft” concepts. With today's high-powered avionics and sophisticated control systems, airline operators expect better performance and would no longer accept weak links in the system that need frequent maintenance. One of the weakest points in an electric generator is its reliance on rolling element bearings, which are subject to unpredictable and frequent failures. Huge redundancy and frequent maintenance ensure uninterrupted supply of electricity in an aircraft.
Technical Paper

Development and Application of a Real Time Bleed Air Contamination Monitor

The bleed air contamination monitor was developed at Honeywell to ensure that our products provide the highest quality bleed air to aircraft environmental control systems. The bleed air contamination monitor is currently for ground based applications only. It is being developed into an on board system for future applications. Current Aircraft Cabin Air Quality measurement techniques are very labor intensive and require days or even weeks of laboratory analysis to provide results. This is unacceptable from a manufacturing and service perspective. Development of a real time analyzer began in the early 1990s and has progressed to a point where a product is ready for introduction that not only provides real time information regarding engine air contamination, but is also easy for operators to use with a minimum amount of training.
Technical Paper

Corrosion Testing of Brazed Space Station IATCS Materials

Increased nickel concentrations in the IATCS coolant prompted a study of the corrosion rates of nickel-brazed heat exchangers in the system. The testing has shown that corrosion is occurring in a silicon-rich intermetallic phase in the braze filler of coldplates and heat exchangers as the result of a decrease in the coolant pH brought about by cabin carbon dioxide permeation through polymeric flexhoses. Similar corrosion is occurring in the EMU de-ionized water loop. Certain heat exchangers and coldplates have more silicon-rich phase because of their manufacturing method, and those units produce more nickel corrosion product. Silver biocide additions did not induce pitting corrosion at silver precipitate sites.