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A multiplex communication system has been developed for the Ford Alternative Fuel Qualified Vehicle Modifier (QVM) program, linking the vehicle's powertrain control module (PCM) to the alternative fuel (natural gas or propane) control module (AFCM). The system allows precalibrated diagnostic routines (OBD and non-OBD) to be selectively modified and disabled which otherwise would be affected by alternative fuel operation. The system enables the broadcasting of selected information from the PCM for use by the AFCM. An additional benefit is smoother transition between alternative fuel and gasoline operation when the gaseous fuel is depleted. Also, improved emissions on the alternative fuel have been noted due to the link. System development and function are detailed in this paper.

A novel piezo-fluidic gaseous fuel injector system designed for natural gas engines is described in this paper The system consists mainly of no-moving-part fluidic devices and piezo electro-fluidic interfaces The steady state and dynamic characteristics of the system were tested on a laboratory experimental rig The results show that the system can handle the large gas volume flow rate required by natural gas engines and is capable of operating via pulse width modulation. A few typical commercial solenoid type gas injectors were also tested and the results were compared with those from the piezo-fluidic injector system. It was found that the piezo-fluidic gaseous fuel injector system has faster switching responses and smaller injection cycle-to-cycle variations

Throttle tip-in and tip-out tests on a 2.0 litre passenger car engine were performed using four different natural gas fuelling systems an air-valve or variable restriction type mixer, a venturi type mixer, central fuel injection, and port fuel injection. The in-cylinder fuel-air equivalence ratio, ϕ, was measured using a fast response flame ionization detector sampling about 7 mm from the spark plug gap. The data reveal characteristics of each fuel system's in-cylinder fuel-air ratio response and torque response.

This paper describes experimental studies carried out as part of a program to develop a neat methanol (M100) version of a GM 4-cylinder light truck engine. The engine was originally intended for variable fuel applications with fuels containing up to 80% ethanol. To permit M100 operation, a variable energy ignition circuit and special recessed surface gap ignitors have replaced the standard ignition components. This is referred to as a “plasma jet” ignition system, and is employed both to overcome the cold starting difficulties inherent with neat alcohol fuel and to permit less enrichment to be used during start-up in the interest of reduced hydrocarbon emissions. The plasma jet ignition systems used in previous related studies suffered from excessively high ignition energy requirements which would be detrimental to ignitor durability.

Tins report describes the experimental procedure used to evaluate the effect of selected fuel components (butane, propane and propene) of liquefied petroleum gas (LPG) on both regulated and speciated exhaust emissions. A total of seven LPG fuels were tested on three different vehicles. FTP-75 emission tests were conducted on each fuel blend for all three vehicles. Full hydrocarbon and carbonyl speciation were included for at least one test on each fuel. In general, fuel composition effects on post catalyst emissions were overwhelmed by vehicle to vehicle differences. There was no clear indication that one fuel showed best emissions in all vehicles. Results also suggest some dependence upon initial LPG fuel system calibration. Data presented here may lend itself to further statistical analysis which is beyond the scope of this paper. These mixed results suggest that more research is needed to provide greater insight on the effect of LPG fuel components on vehicle emissions.

A range of gasoline/alcohol blends containing methanol, ethanol, iso-propanol and n-propanol, up to 5% oxygen content by mass, was tested in a multi-valve production engine to quantify the raw exhaust emissions, performance and burn-rate. A heat-release model was developed to facilitate the quantification of burn-rate. The engine was operated with various control strategies to enable the results to represent the response of different engine types. With standard open-loop engine calibration the alcohols reduced the equivalence ratio which resulted in increased combustion duration and reduced regulated emissions, while there was no difference between the effects of the different alcohols.

A new Electronic Gantry Applied Drilling System has been developed and demonstrated which provides a CNC controlled, multi-axis drilling system to replace hand drilling and countersinking operations at Assembly Jig Stations. Therefore improving hole quality while reducing touch labor and tooling costs. The system has statistical process control capabilities which confirm position accuracy for tooling details, parts holes.

Under Contract No. N00019-93-C-0006 EMD with the Department of the Navy, Bell Helicopter Textron Inc. (BHTI) conducted a Manufacturing Process Verification Test as part of the V-22 Engineering Manufacturing Development process. The objective of this test was to develop a “One Step” drilling solution for peck drilling close tolerance holes in V-22 major assemblies. These assemblies consist of Titanium / Graphite / Titanium and Aluminum / Graphite compositions. The V-22 is a graphite / epoxy composite structure that has metal detail parts mechanically attached to the basic structure. Attachment of these detail parts is accomplished with two piece titanium fasteners that require a close tolerance of .003″ per hole. To achieve this tolerance a drill / ream process is currently used.

A new wing panel riveting cell capable of replacing tack fasteners and performing small repair jobs has been developed. Using two mobile scissor lift platforms with electromagnetic riveters mounted on each, the operators can access every portion of the wing panel without the use of ladders or platforms. This method minimizes fatigue, allows workers to carry all tools and supplies with them, meets current safety standards and minimizes coldworking of the components.

This technical paper will address the advancements made in the area of automatically riveting complex double-contour 180 degree fuselage panels. Detailed is an automatic fastening system that accomplishes the aforementioned task in a single workframe mounted panel/fixture sequence. Through the use of innovative machine motions and enhanced adaptive controls, increased production throughput for difficult to rivet panel assemblies has been realized.

A new control architecture has been utilized to control an “anti-wink” automatic slug riveting process which improves fastening accuracy, reliability and cycle time. Cycle rates are equal to or better than that of conventional slug riveting. This technique of fastening provides for virtually no work piece movement during the forming process allowing for the use of rigid fixturing.

Two new concept of flexible fixture subsystem (FFS) for aircraft wing spar assembly are introduced in this paper. The advantages and characteristics of FFS are discussed and compared with the current assembly method and fixtures. The objective of FFS is to replace the dedicated tooling and be able to quickly reconfigure itself for new types of spars. The fixture enables a family of spars to be mounted and assembled in the same tooling. Left- and right-hand side spars, varying lofts(spar cap angles), height, and depths are all accommodated on the same tool, within its envelop.

McDonnell Douglas Aircraft in St. Louis, MO manufacturers various transport and fighter military aircraft such as the C-17 and the F/A-18. With shrinking military budgets and increased competition, market forces demand high quality parts at lower cost and shorter lead times. Currently, a large number of different fastener types which include both solid rivets and interference bolts are used to fasten these assemblies. The majority of these fasteners are installed by hand or by using manually operated C-Frame riveters. MDA engineers recognized that in order to reach their goals they would be required to rethink all phases of the assembly system, which includes fastener selection, part fixturing and fastener installation methods. Phase 1 of this program is to identify and to develop fastener installation processes which will provide the required flexibility. The EMR fastening process provides this flexibility.

Many of the large CNC controlled riveting systems that were purchased in the late 1970s and 1980s are beginning to show signs of dated technology. To protect the original investment in this equipment, aerospace companies are looking into refurbishing these machines. Issues such as pre-planning, teaming concepts, communications, and a thorough understanding of the equipment are essential to a successful project. This paper is based on the case history of one such refurbishment project.

This paper is focusing on considerations pertaining to riveting/fastening systems and assembly methodology currently in use for large aircraft fuselage structures. Discussion of process principles on which current systems are based is addressing distribution of rivets along the aircraft structure, riveting/fastening systems and equipment flexibility. An attempt was made to predict the most probable future equipment development trends based on the need for more efficiency in all aircraft structural assembly and in high level and final assembly areas.

Airframe manufacturers have radically changed their operational approach to improve the affordability of their products. The deployments and use of automated fastening equipment has changed as well. Many manufacturers have adopted a cellular manufacturing flow model as a method to reduce cost, inventories and work-in-process. Automated fastening equipment can be integrated into a cellular manufacturing environment as free-standing service cells or dedicated to a specific cell. The operational techniques and the machine capability requirements differ from the traditional factory operation and layout.

The multiple axis flexible CNC riveting cell consists of three major systems: a multi-axis part positioner, a multiple head drill and rivet machine and a multi-bowl rivet feed system. The CNC positioner has seven axis of control; the five common axis of X, Y, Z, Alpha, and Beta plus lower ram position and tool position on the knee style lower ram. The six function rivet head contains a pre-drill spindle, a rotary spin dimple spindle, a final drill spindle, a sealant applicator, a rivet insertion station and a rivet shave spindle. The unique lower knee style ram will allow the machine to fasten small radius high curvature parts as well as flat panels with minimal changes. The fastener feed system utilizes a bank of vibratory bowls that feed fasteners through a single feed tube. The fasteners are allowed to tumble and then are aligned prior to insertion into the anvil fingers. Countersunk fasteners as small as -4-3 will be fed by the system.

Machine vision systems, having been in use for a number of years on specialized applications, are now being more commonly used in new machines to enhance accuracy and in older systems to achieve today's tolerance requirements without major mechanical refurbishment. Additionally, the data received from such systems is being used to create custom machine routines which provide useful tools on parts where complete numerical data is not available for programming. This paper will discuss how the need for such a system arose at Northrop Grumman and the solution developed.

A new freshman course is currently being developed and taught on a pilot basis to approximately 40 cadets per semester at the United States Air Force Academy. The purpose of the course is to better address the educational outcomes desired in Academy graduates. Problem Base Learning is used to present engineering as a problem solving process that involves a variety of interdisciplinary issues. The pedagogical setting for student teams is an Air Force System Program Office responsible for planning a deployment mission to put a research team on Mars. Students are guided by mentor-instructors to identify the relevant tasks and engineering requirements pertinent to the plan. Traditional instruction is used sparingly only to present tools that enhance students' learning. An integrated assessment program is also part of the course development. It is being used to determine the value of this instructional approach, and how well the educational outcomes are being met.

The commercial aviation maintenance industry has been changing rapidly for the past ten years. Declining demand and overcapacity, shifting market/financial forces, and issues of personnel training and technology have combined to drastically change the business of maintaining air transport fleets. This has placed great stress on existing maintenance organizations who must struggle to survive. This paper describes one approach which can be used by aviation overhaul and maintenance service providers to devise new growth and management strategies. The approach, known as Market Driven Maintenance, uses classic product marketing strategies to help aircraft maintenance centers adjust scheduling and marketing strategies to attract new and more profitable market segments.