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This paper describes the typical development process for avionics hardware and how this relates to the systems and software processes. The decline in availability of military components and the consequential impact on equipment design, manufacturing and support is discussed. Some solutions to the problems arising are proposed.

Aircraft manufacturers spend millions of dollars reworking blown fastener holes, especially in portable tool drilling situations. Oval, tapered, rifled, and oversize holes are costly rework issues currently commonplace in the industry. The most common causes of imperfectly drilled holes include spindle runout, insufficient clamp and feed force, out-of-balance drill feed forces, spindle windup, and lack of adequate feed control. This paper will focus on a next-generation drilling machine that utilizes a unique combination of hydraulics and pneumatics to solve the problems associated with legacy drilling units. Several design elements will be examined, such as the use of an on-board, 1000 PSI hydraulic pump, controlling both drill feed and clamp force. This greatly reduces the size and weight of the clamp and feed cylinders compared to legacy air systems, while increasing their force and rigidity.

The sleeve cold-working process for fastener holes is a process that uses a tapered mandrel in conjunction with a disposable, prelubricated split sleeve to compressively prestress a significant zone around a fastener hole. This compressive prestressing offsets the stress concentration of the hole itself to produce substantial improvements in structural fatigue performance of fastened joints. The sleeve method allows higher degrees of prestressing than are possible with other methods and does not require precision controls and skills germane to other fatigue-rated hole preparation/fastener systems.

Commercial airlines use a variety of hydraulic fluid mixtures, some of which had been reported to cause increased valve erosion. An extensive test program was conducted to determine why certain mixtures of aircraft phosphate ester hydraulic fluids cause erosiveness in valves while others have negligible effect. Use of nonerosive mixtures is important to the aircraft industry to reduce the high cost of maintenance caused by erosion. Accelerated tests were conducted to identify erosive and nonerosive mixtures of presently available fluids. Chemical tests were conducted with a matrix of test fluids to establish methods that will predict the effects measured in erosion tests. Erosiveness of fluid mixtures can now be predicted by means of two laboratory measured electrochemical properties; wall current and threshold corrosion current density.