Interconnect Product Showcase
Glenair's Manufacturing Model and Qualification Process
In the F-16 Falcon, every available square inch of internal wing and body space is used to carry either fuel, ordinance or a critical air borne system. Usable space is at such a premium, that the cable harnesses used to transmit fuel consumption data, signal the Fly-by-Wire flight control system, and provide connectivity to and from critical avionic devices must travel directly through the jet's internal fuel tanks - a design and engineering challenge of the first order.
Total Immersion Fuel Tank Air-Borne Cables (TIFTAC) must exhibit extremely high integrity while fully immersed in jet fuel, lubricating oil, hydraulic fluid and other liquid chemicals. The cables must be able to withstand penetration and degradation from these caustic fluids for their entire lifespan, as any failure could potentially cause a dangerous flight safety condition. This is especially true since the F-16, for reasons of efficiency, performance and resistance to battle damage, carries no mechanical backup to its electronic flight control system. That the F-16 TIFTAC cables must provide such faultless performance under extreme conditions of strain, vibration, shock, and sudden changes of pressure and temperature only adds to the challenge of engineering and building these mission-critical cable assemblies.
In the first few decades of flight, aircraft were controlled through direct force - moving control sticks and rudder pedals linked to cables and pushrods that pivoted control surfaces on the wings and tails. As engine power and speeds increased, more force was needed and hydraulically boosted controls emerged. In the early 60's, NASA engineers began work on an electrical Fly-by-Wire (FBW) control system which would provide aircraft engineers with more flexibility in aircraft design and architecture, especially in the placement of control surfaces.
Fly-by-Wire systems matured rapidly, and in 1976 General Dynamics took the step of eliminating backup hydromechanical controls from the design of its FBW F-16 Fighting Falcon - making it the first high-performance aircraft to rely completely on electrical wires to relay flight commands, instead of the usual cables and linkage controls. F-16 pilots apply hand pressure to a side stick controller which sends electrical signals to actuators of flight control surfaces such as ailerons and rudder. Avionics systems, including navigation, radar, instrument-based landing systems, warning systems, fuel consumption gauges and so on, also rely on this same electrical interconnect cabling which passes through sealed bulkhead fixtures, and into and out of the jet's internal fuel tanks.
The F-16's Fly-by-Wire control system has evolved over the years from a four channel analog system to the quadraplex digital FBW system used in today's F-16/C and D designs. But regardless of the nature of the electrical signal, a specially fabricated fuel cell cable assembly is used to house and protect the copper conductors as they intersect the F-16's internal fuel tanks. The overmolded cable assembly consists of custom bulk multi-conductor cable, circular Mil-Spec multi-contact connectors, machined molding adapters, bulkhead feedthrough connectors, various breakout support plates and reinforcing members, and a fluorlastomeric (Viton®) cable jacketing.
Zero-Defect Manufacturing Model
Developing manufacturing, assembly and test procedures which will insure "zero defect" quality standards and strict adherence to customer/military qualification specifications is the first order of business when building TIFTAC and other mission-critical cable assemblies. The assembly of high performance interconnect cables for use in military and commercial applications is simply not possible in any setting other than a tightly controlled, 100% inspection and test environment. Glenair's over-molded cable assemblies are manufactured in just such a setting, and meet the most stringent reliability requirements for rough handling and harsh environmental conditions.
The harnesses are typically manufactured using either one-of-a-kind transfer molds or high volume injection molding machines. In the case of the F-16 TIFTAC, a range of new injection molding equipment and tooling was required to meet the production forcasts and quality control requirements of the customer, General Dynamics - Fort Worth.
F-16 TIFTAC cable assemblies are fabricated in accordance with General Dynamic's original specification control documentation and a host of relevant Mil-Spec standards in a tightly controlled "closed-loop" assembly process. In order to qualify to produce the F-16 TIFTAC assembly, and to extend the qualification by similarity to other fuel tank cable assemblies, Glenair instigated dedicated TIFTAC manufacturing controls and procedures which effectively segregated the entire fabrication process from the rest of the shop floor. From the receipt and storage of incoming materials to the final test and inspection of the finished cables, TIFTAC manufacturing is accomplished with dedicated personnel using controlled tooling and equipment. The manufacturing control procedure followed by Glenair in the manufacture of the F-16 TIFTAC includes the following major steps and controls:
- Incoming material inspection and storage: all materials are inspected upon receipt and segregated in a controlled TIFTAC stock room.
- Bulk cable fabrication: specially trained staff insure 100% inspection and test of color coding, lay length and direction, tape overlap, cable tension, diameter, respooling and storage.
- TIFTAC cable jacketing: cutting, breakout, hand lay-up, taping and Viton® jacketing is completed in preparation for interconnect component installation and termination.
- Surface preparation of component parts: Special Glenair proprietary processes insure proper adhesion of molding compounds to plated components.
- Breakout and bulkhead feedthrough molding: specialized interconnect components and cable breakouts are abraded, primed and molded in place using special Glenair proprietary processes.
- Connector termination: trained and certified staff position molding adapters and follow provided assembly instructions to complete crimping, termination and 100% in-process inspection.
- Connector molding: molding adapters are prepared and installed to connectors using thread sealing compound. Curing, potting and Viton® molding and over-molding is completed according to exact manufacturer's specifications.
- Identification: color coding, stamping and identification documentation is completed prior to final inspection.
- 100% final inspection: appearance, identification, dielectric, continuity, and insulation tests are completed on a 100% basis in preparation for final customer source inspection.
Glenair's three cable harness assembly plants in Glendale California, Chicago Illinois and Mansfield England provide completely wired, terminated, and tested products ready for immediate use. Glenair has produced thousands of individual cable assembly designs - from "The Golden Umbilical" used in the first US space walk to precision fiber optic systems and microminiature harnesses used in military, commercial and industrial applications. Glenair has qualified to build some of the most difficult and challenging interconnect assemblies in the industry, and has earned its reputation as a reliable supplier of high-performance, mission-critical cable harnesses one cable at a time.
Glenair has been manufacturing fuel tank cable assemblies since 1984 when it first received qualification to build these high-reliability total immersion cables for the F-16 fighter. To date, Glenair has manufactured over 35,000 F-16 TIFTAC cable assemblies with zero real-time failures. The procedures developed by Glenair to meet the high quality standards specified by General Dynamics-Fort Worth, the original manufacturer of the F-16, have been applied successfully by the company to similar assemblies for the F-18, the F-22, the V-22 and the F-2 (the Japanese version of the F-16). It goes without saying that qualification to build such mission-critical interconnect harnesses is achieved only after considerable research and development. The fuel cell cable for the F-18, for example, is a unique over-molded hybrid electrical/fiber-optic design which very few manufacturers in the world would even attempt, let alone successfully qualify to the exacting specifications of the manufacturer.
Qualification to supply the F-16 TIFTAC assemblies was achieved by Glenair following extensive prototyping. Representative samples of the F-16 TIFTAC cables were subjected to qualification testing by National Technical Systems, an accredited testing lab. The qualification procedure for these assemblies included the following performance tests and laboratory analysis, all of which were passed successfully by the Glenair produced cables:
- Continuity/Circuit resistance
- Insulation resistance
- Dielectric withstanding voltage
- Water immersion
- Mechanical strength (pull test)
- Mold adhesion
- Strain relief
- High temperature resistance
- Low temperature resistance - storage
- Low temperature resistance - operating
- Moisture resistance
- Fluid compatibility (short term)
- Fluid compatibility (long term)
- Low temperature flexibility
- Volume resistivity
Glenair's unique ability to develop qualified manufacturing processes which meet the exact needs of its key customers is a strength only rarely found in the interconnect industry. In the case of the F-16 TIFTAC program, this ability resulted in rapid qualification, the on-time fulfillment of tens of thousands of orders, and an impressive 15 year track record of spotless performance.
Glenair has used the experience gained in producing the F-16 fuel cell cable to build a wide range of other high-reliability assemblies for use in fuel cell environments, many of which are so unique and demanding that Glenair is the only qualified source.
The special processes and materials developed by Glenair which insure proper adhesion of molding materials to the interconnect sub-assemblies, as well as a host of other skills gained in the course of servicing the F-16 TIFTAC program, have made Glenair the supplier of choice for these demanding, mission-critical cable assemblies.
Glenair's unique capabilities in fuel cell cable manufacture include:
- Three tightly controlled, 100% inspection and test manufacturing plants, complete with value-added engineering services and an abundance of manufacturing and assembly capacity.
- Complete cable over-molding and jacketing capabilites using Viton®, Butyl, Neoprene and other harsh environment coverings as well as NBC (nuclear, biological, chemical) materials.
- Custom fiber optic and electrical cable extrusion capabilities and one of the industry's broadest selections of metal and fabric shielding and sleeving.
- Proven shielded and unshielded designs for virtually any environmental or electromagnetic application.
- Standard Mil-Spec circular connector assemblies as well as complete Micro-D and nano harnesses and pre-wired connectors.
- ISO 9001, BSENISO9000, MIL-I-45208A and MIL-Q-9858A quality systems.
In addition to being the world's leading manufacturer and supplier of electrical connector accessories, Glenair offers a complete range of fiber optic systems, specialty connectors, conduit, composite thermoplastic components, microminiature connectors, assembly tools and custom cable assemblies. Glenair maintains the world's largest inventory of commercial and Mil-Spec connector accessories, and the industry's fastest turnaround on quotes and custom orders. Our worldwide presence has made Glenair the supplier of choice for companies whose business interests, like ours, span the globe.
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