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Aircraft and military ground vehicles are exposed to extreme environmental conditions, not the least of which is vibration. Safety and reliability considerations have led to a variety of locking mechanisms. Until recently, the most effective solution for securing switches, sensors, hydraulic actuators and many other external components was safety wire. A new locking washer concept has been developed that provides safety, quality and cost advantages over safety wire for many of these applications. This concept has found use in military land vehicles, helicopters and aircraft including over 400 fastening applications on the F-22 fighter.

Several assembly factors have a predictable effect on structural durability of commercial airframes. This paper will discuss the importance of fastener interference and fastener tension (preload). The impact of manufacturing tolerances on these installation factors will be reviewed, as will benefits of reducing variation and targeting the process.

The Hi-Set Fastening System is a high strength (95 KSI shear) single piece fastener used for automated airframe assembly with squeeze type assembly equipment. As the demands for improved surface quality, shorter cycle times and lower cost increase throughout the airframe industry, automated assembly is becoming more attractive. The design detaiils, installation tooling, installation sequence and cost effectiveness of the Hi-Set are reviewed and compared to other fastening systems.

Traditionally, large airframe structures have been assembled on hard tooling, a laborious unforgiving process. Beginning with the C-17, servo-assisted positioning tools have been used to enable faster fit-up, and better understanding of best fit options. Positioner technology has been used in large structure assembly for the 777, and the next-generation 737, and is now being implemented on other transport and civil aviation aircraft. While returning benefit to the airframe manufacturer in terms of improved fit-up and reduced cycle time, these systems are expensive and are not generally adaptable to change in product form or market demand. This paper provides an overview of positioner development and present status, and describes a series of options and initiatives that can make the technology less expensive, and easier to install, use, and maintain.

Throughout the years aircraft producers have struggled with the elusive goal of “Automated Assembly of aircraft structures”. This goal has been attempted in conjunction with and tempered by the basic reality of current aircraft manufacturing methodology. Automated systems have been used for years, but have almost exclusively been based on time tested technology, the derivation of which is “C Frame” riveters. There have been attempts to automatically move the panels, skins and bulkheads using CNC equipment. There have been other attempts to move the riveting head itself; however the basic premise has been a two sided fastener. There are many new technologies attempting to modify the basic paradigm, aircraft are for the most part held together by rivets. The art remains to a substantial degree unchanged.

This paper reviews today's aircraft wing production assembly methodology and technologies as well as innovative ideas for advancing the high-level wing assembly state-of-the-art. Automated wing assembly systems are only being utilized to rivet/fasten first level subassemblies like panels, spars, and ribs. All other high level assembly tasks are performed manually, incurring associated increases in recurring costs due to production inefficiencies, long lead times, expensive rate tooling, and difficult assembly tasks performed inside small wing compartments. Existing assembly methods, process parameters, and the process characteristics of manual, machine, and man/machine systems provide many opportunities for improving wing assembly.

These investigations are conducted to develop new fasteners and joining methods to reduce weight and improve fatigue life of aircraft structures. Three major modes of structural failures; fatigue, fretting and stress corrosion are discussed with recommendations for improvement. Stress coining was developed to cold work aircraft structure for fatigue improvement. Standard stress corrosion test blocks have been designed for evaluation of this failure mode. A crown flush rivet configuration has been developed that does not require head shaving after installation. Qualification tests were performed in compliance with MIL-Std-1312 to obtain FAA and military approval. Various new fasteners have been developed for aluminum, graphite-epoxy and titanium structure. These fasteners were designed to be forgiving to the hole in that they will fill and prestress the hole uniformly without being extremely sensitive to hole preparation quality.

With the increase in technical complexity of machine control systems, there is more demand than ever for field service technicians and engineers to be able to establish a remote communication link to the customer's machines for diagnostics and trouble shooting purposes. This paper will discuss current control architectures and explain Gemcor's approach to establishing remote communication to these technologies. The demonstration will explore making the connection over the Internet and direct phone lines.

This paper presents a detailed overview of the advantages and benefits of using 2-D barcodes, called Data Matrix codes, on Wing Fastening System (WFS) Tooling. This project was conducted on, but not limited to, the 777 Wing Fastening System (GEMCOR) tooling including the drills, fingers, and button dies. This paper will show how using Data Matrix codes to identify tooling will: Eliminate excessive downtime due to the operator using the incorrect tooling for a given tool setup. Reduce the cost associated with panel rework due to the use of incorrect tooling. Reduce the cost associated with excessive tool inventory or last minute ordering to keep up with production needs. Track tool life information for each specific tool. Provide operators with an easy to use tool setup reference document. And provide the factory with the ability to trace panel damage or defects back to the specific machine and exact tooling used.

As the aerospace industry approaches the 21st century, high standards of quality and the need for innovative solutions in automated fastening has prompted new developments in automated fastening equipment. Applying today's current technology to a concept created decades ago, Machine Dynamics has designed and produced an all-electric riveting machine. Utilizing roller screw technology with a servo driven motion control system, the all-electric riveter offers the power and speed heavy production demands without the use of hydraulics. This paper explains the origins of the electric riveter, the roller screw technology being applied to today's production equipment, state-of-the-art control system required and the unique features that are a direct derivative of the electric system.

The decision to use Simulation and Off-Line Programming (OLP) technology leads a manufacturing company into an expanse of long term consequences. These experiences can be very positive if the manufacturing company approaches the project correctly. This paper addresses the factors to attain success after feasibility studies are complete and a decision to pursue this technology has been made. These factors include the development of a vendor selection method, in addition to the implementation and maintenance processes vital to a thriving project. The right techniques and information can lead a company to choices that will contribute significantly to higher levels of project success.

The Automated Spar Assembly Tool or ASAT was originally developed for the Boeing 767 wing spar in the late 1970s. Since then this powerful concept has been further advanced and integrated into nearly all the current Boeing commercial wing lines. A fourth generation system, ASAT4, has been developed for the Boeing C-17 Globemaster III. ASAT4 provides an unprecedented level of flexibility in a minimum amount of floor space. Similar to ASAT3, ASAT4 consists of a vertical traveling yoke machine which straddles the spar fixtures. Two fixtures placed end to end form a system approximately 220 feet in length which is serviced by a single machine. This allows manual operations, e.g. load and unload, to be performed on one spar while the machine works in the adjacent cell. Each fixture can accept any of the six C-17 spars. Fixture reconfiguration between spars is completely automatic. The single three axis yoke machine, the E5000, travels the full system length.

Fasteners are currently being fed into automated installation machines by a variety of different devices. Once fed, the fastener often travels to the machine's installation point via a track or feed tube. Some tracks and tubes keep the fastener oriented while others allow the fastener to tumble and reorient it at the machine head. Fastener escapements, shuttles, tracks, blow tubes and injectors are all part of the overall system. Fastener grip length selection and fastener inspection devices add to the overall complexity of feeding systems. The technical paper discusses the theory and operation of each of the fastener feeding devices including; hoppers, magazines, cassettes and vibratory bowls. Support systems are covered and methods to optimize fastener feed times are presented.

Early experience with precision farming technology suggests that some hardware and software may follow a rapid S curve adoption path, but that the use of integrated precision farming systems may take longer to develop and be subject to false starts and periods of stagnation. Yield monitors appear to be following a classic S curve adoption path. Precision farming adoption is like that of hybrid corn because changes in organizations will be required to use it effectively. It is like motorized mechanization because it is coming on the market in an immature form and lends itself to farmer tinkering.

An international standard for nonroad engines has been developed that comprises gaseous and particulate emissions measurement procedures, smoke testing, test cycles, and an engine family and group concept. Through a joint effort of industry and government agencies, ISO 8178 has become the basis for emissions legislation in the USA, the European Union and Japan and of the International Maritime Organization. The ultimate goal of worldwide harmonization for the worldwide engine industry has been reached, but much effort is still needed to maintain the level of harmonization achieved today. The validity of ISO 8178 has been demonstrated on a round robin test with three engines of 19 to 170 kW circulated around 28 test laboratories. Test-to-test repeatability was generally lower than 10 %. Lab-to-lab variability was less than 10 % for NOx and particulates, and over 25 % for HC and CO. The equivalence of partial flow and full flow dilution systems for particulates has been proven.

Six heavy-duty diesel engines were tested for exhaust emissions on the ISO 8-mode nonroad steady-state duty cycle and the U.S. FTP highway transient test cycle. Two of these engines were baseline nonroad engines, two were Tier 1 nonroad engines, and two were highway engines. One of the Tier 1 nonroad engines and both of the highway engines were also tested on three transient cycles developed for nonroad engines. In addition, published data were collected from an additional twenty diesel engines that were tested on the 8-mode as well as at least one transient test cycle. Data showed that HC and PM emissions from diesel engines are very sensitive to transient operation while NOx emissions are much less so. Although one of the nonroad transient duty cycles showed lower PM than the steady-state duty cycles, all four of the other cycles showed much higher PM emissions than the steady-state cycle.

This paper proposes a new flexible system concept applicable to diesel engines which will achieve the compatibility of high BMEP (Break Mean Effective Pressure) and low fuel consumption. The high BMEP means constant power from low speed to high speed (the power density will be 60ps/liter for truck applications, 87ps/liter for marine applications and 109ps/liter for racing boats). BMEP will be over 32kg/cm2. The low fuel consumption means a wide range of speed and torque having a good match to the best turbocharger efficiency. Before feasibility testing of an engine a basic simulation has been done and is introduced in this paper.

Bubbles in working fluids have much influence on the performance of fluid power systems. One of the authors has developed a novel device for bubble elimination capable of eliminating bubbles and decreasing dissolved gases using swirl flow. In this paper, performance of bubble removal in oil flow is studied through numerical analysis of the swirl flow in the device. This paper also documents a reduction of oil temperature rise and removal of entrained air from the working fluid in the hydraulic circuit by use of the device. It has been confirmed that the device is effective keeping the oil temperature low in the fluid power system.

Cavitation is a common and usually undesirable phenomenon in hydraulic systems. Understanding the basics of cavitation phenomenon as well as detecting existing cavitation are important in order to prevent cavitation in hydraulic systems. In this paper past studies of orifice cavitation are discussed and also new studies of orifice and valve cavitation with hydraulic oils are presented. Cavitation behaviour of different kinds of orifices and a poppet valve have been studied. Studies were done with different cavitation numbers. Rough design guidelines for reducing and preventing cavitation in orifices and valves are presented.

Tribological systems in hydraulic pumps, motors and cylinders are considerably stressed by friction and wear. Working life of components in hydraulic circuits might be extended by the use of wear resistant materials. Modern processes like Thermal Spray Technology, Physical Vapour Deposition and Plasma Nitration enable the application of wear resistant coatings with excellent friction characteristics. A wide variety of diffe-rent coating materials is available with various proper-ties concerning surface hardness, surface structure and coefficient of friction. Thus, an adaptation of surface properties and loads can be achieved. This paper presents results from investigations of coated simplified specimen and from tests with coated fluid power components.