November 2001

Welcome to The CTMA Connector, a monthly newsletter designed to provide news and ideas about the Commercial Technologies for Maintenance Activities (CTMA) program. The CTMA program is a joint Department of Defense/National Center for Manufacturing Sciences (DoD/NCMS) effort promoting collaborative technology development between industry and the DoD maintenance and repair facilities. This newsletter highlights ongoing projects, serves as a forum for promoting new project ideas, and provides other news of interest to the program. Our goal is to stimulate your participation and solicit your input. Feel free to submit items for the newsletter as well as any suggestions to make it more useful. More information about the program can be found at http://ctma.ncms.org. To subscribe or unsubscribe to the CTMA Connector, send a message to CTMAConnector@ncms.org with "subscribe" or "unsubscribe" in the subject line.

Ongoing Project News

CTMA funds for FY02: Although the fiscal year began on October 1st, the Defense Appropriation bills in the Congress have not been completed. The Senate has been stalled on its bill due to the inclusion of emergency spending as a separate title. With Congress in recess this week, any action will be taken after the Thanksgiving holiday.

The following technologies were developed by or available through the consortium members of the Leak Test Technology Development Project:

Photo Acoustic Leak Detection (PA): The PA technology has sensitivity similar to helium mass-spectrometers (~1E-5 sccs) and can locate leaks in free air (no vacuum chambers and pump down times) using a part charged with SF6 and an infrared (IR) laser that is raster scanned over the part. Leak sites that are illuminated by the laser light will make a popping sound as the SF6 gas strongly absorbs the laser light. This sound emitted at the leak site has harmonics that are integer multiples of the laser scan frequency. Recovery of the SF6 is desirable from a cost and environment point of view. This system is being developed under a Consortium formed by Ford, the National Center for Manufacturing Sciences, Vacuum Instrument Corp., Laser Imaging Systems, Argonne National Laboratory, Honeywell FM&T, and the University of Michigan.

Speed of Sound Sensor (SoS): A rugged hand sensor from Argonne National Laboratory that can detect gases with different molecular rates than that of air. The SoS can locate leaks < 10E-3 sccs of Helium and Hydrogen, and other gases with molecular weights different from air such as Freon, SF6, etc. If a part fails a Helium mass-spec test with a 10^-4 range leak, the location of leak sites on parts could be sensed with the SoS. We have piloted this sensor at the Jacksonville Naval Air Station checking for fuel system leaks in F-14 fighter aircraft, and we also piloted this technology at Ballard to locate specific leak locations to assist the repair fuel cell units. Future pilots are scheduled for testing on powertrain component applications at DaimlerChrysler and defense production applications at Honeywell FM&T. This sensor also can detect the presence of particulates in the air, in environments such as fire fighting and as a vehicle exhaust sensor.  This system is also being developed under the Consortium.

In a follow-on project, we anticipate piloting these and additional nondestructive leak test technologies such as a portable mass spectrometer. Contact Connie Philips at 734-995-7051 to discuss your application and leak test needs and to determine if we have a suitable solution to solve your leak detection problem.

With composite materials becoming more prevalent in present and future aircraft structures, the need for quick and structurally sound composite skin repair is growing accordingly. Currently, the repair of damaged composite aircraft structures requires time-consuming methods that are reliant on manual processes. This is particularly true in the repair of high performance composite structures, where repairs are typically required to retain the aircraft’s outer moldline. These repairs are referred to as flush or near-flush repairs and often require the damaged region of the aircraft to be scarf-machined prior to installing a repair patch. The current state-of-the-art in accomplishing scarf-machining is through the use of manual routing tools manipulated by aerospace technicians or aircraft maintenance personnel. This machining step accounts for a large portion of the time required to complete the repair and typically can involve several days of arduous hand labor. A meaningful reduction in the maintenance burden of composite aircraft repairs requires that the time spent scarf-machining the damaged structure be reduced to periods of a few hours.

Lockheed Martin Aeronautics Company is proposing to complete development of the STARC Automated Scarf Routing system recently established by PushCorp Inc. under a Navy sponsored small business innovative research program (SBIR). In its current form, the STARC router has demonstrated the unique ability to accurately scarf-machine mildly contoured composite structures using a fully computer controlled Stewart Platform manipulator. This first generation STARC router system successfully eliminates the current repair operations that involve a combination of low technology hand-held rotary grinding tools and highly skilled hourly personnel. This project proposes to adapt the STARC system to address machining of the most critical and frequently repaired portions of advanced fighter aircraft. The composite structures of concern are the leading and trailing edges of the aircraft. The combination of their high susceptibility to in-flight damage and hanger rash along with their critical performance requirements identifies edge structures as major drivers for aircraft sustainment costs. Severe radii and complex contours associated with edge tips, roots and flaps present geometric challenges that the current Stewart Platform manipulator is unable to address.

In response to the limitations of the first generation STARC router, the program team proposes to design, fabricate and test a new robotic manipulator configured for machining fighter aircraft leading and trailing edge structure. The program will also modify the appropriate STARC software modules to control the leading edge manipulator. These modules will perform the required kinematic calculations to position the manipulator throughout the scarf-machining operation. The new manipulator will be designed such that it can be attached to the aircraft via vacuum cups, straps or at hard attachment points. In addition, the manipulator will be able to work in a freestanding mode separate from the aircraft. Further improvements in the current STARC software modules will permit the system to scarf machine pre-cured composite patches, off-the-aircraft which accurately match the machined parent structure located on-the-aircraft.

At the conclusion of the proposed program, working prototypes of the leading edge manipulator and control system will be delivered to participating depot repair organizations. These prototypes will be used to market the benefits of the automated routing system among the military’s many structural maintenance facilities. The demonstrated benefits of the prototype routers are expected to lead to incorporation of the such systems into standard repair manuals used to govern field and depot repair operations. Industry team members will be provided unique rights to procure additional STARC router systems for their internal use.

• Hands-free machining operations and dust control systems increase operator safety
• Eliminates the dependence on highly skilled (artisan) machinists
• Reproducibility and quality of the machined joint is improved. Robotically controlled routers eliminate the variability resulting from hand held routers whose applied loads have been shown to vary from 0 to 5 lbs.
• The ability to provide a software simulation of the machining operation improves quality and trace ability of the repair process.
• Patches of higher cure temperature materials, such as bismaleimides, can be formed, postcured and machined off-the-aircraft to prevent the need to expose sensitive aircraft components to long, high temperature process cycles.
• The STARC’s ability to profile surface contours via an integrated laser mapping system can lead to flat pattern cutting programs for rapid patch fabrication.
• The versatile STARC manipulators can also be used to automate the nondestructive inspection and painting segments of the repair process.

NCMS Develops e-Learning Capabilities

Calendar Items

New Project Ideas (click on topics to see descriptions)