In our August 2004 issue we reported that the saga surrounding the establishment of a fiber optic connector standard "has reached a climatic decision point." It has. But the saga continues. And it no doubt will for some time.
As we noted then, the airline community was intent on establishing a single ARINC standard for fiber optic cable and connectors in order to avoid a repeat of the Ethernet standard for copper wire. ARINC 600 for copper wire and connectors wound up being a dual standard--for both the quadrax and twinax designs--because both types of wire and connector were too far along in development and acceptance to be omitted.
The fiber optic working group, which has been part of the Airlines Electronic Engineering Committee's (AEEC's) New Installations Concepts (NIC) Subcommittee, has the new ARINC 801 standard for fiber optic connectors nearly ready for presentation and formal acceptance at the annual AEEC general session, to be held in Seattle, Oct. 3-6. "We only need to dot some I's and cross some T's," says Dan Martinec, who is with ARINC Industry Activities and serves as the NIC Subcommittee secretary.
ARINC 801 will not be the only fiber optic standard to be approved at the AEEC general session. ARINC 801 is the base fiber optic connector standard, or the "bible," according to Martinec. But committee members also will decide on other components of the 800 series of standards: ARINC 803, covering fiber optic systems design guidelines; ARINC 804, covering active components standards; ARINC 805, covering fiber optic test procedures; and ARINC 806, covering fiber optic cable and connector maintenance. ARINC 802, covering fiber optic cable standards, was approved during the 2004 general session.
Work will continue beyond October on the ARINC 800 series of standards, however. "We haven't started 807 yet," says Martinec. "It will cover fiber optic technician qualification requirements for installation and maintenance."
Fiber optic cable is quite different from copper cable and is more difficult to handle, he explains. "For example, you often need an oven to repair fiber optics, and when you bring an oven on board an aircraft, you need standards, and the line maintenance person needs to have special training."
Martinec adds that, in the fiber optic design document, AEEC's fiber optics working group--which recently has been elevated in status to the Fiber Optics Subcommittee because of the technology's importance to the aviation industry--is looking for ways to repair cable without using ovens to cure epoxy, when epoxy is required. Perhaps the most obvious way to avoid major repair is to have extra cables wrapped into the wire bundle to substitute for faulty ones. "The spare cables could even be preterminated," says Martinec. Since fiber optic materials are quite lightweight, the extra cables will bring only a minor weight penalty.
These and other issues will be ironed out over a two-year period. Martinec says the subcommittee plans to have ARINC 807 completed by 2007.
So now we have a single standard in the making, right? Well, yes--essentially.
The ARINC 801 standard is based on the LuxCis terminus, developed by Radiall Jerrik, which is headquartered near Paris and has a U.S. office in Tempe, Ariz. It is the connector design that Boeing favors for its new aircraft. However, the ELIO connector, developed by Souriau Connection Technology, is favored by Airbus. Souriau also is based in France and has a U.S. facility in York, Pa.
A standard for the ELIO terminus--also known as the "European design"--already has been established, but not by ARINC. Instead, it is the design basis for the European Norm (EN) 4531 standard, drawn up by the Association Europeenne des Constructeurs de Material Aerospatial (AECMA) and approved by the Bureau de Normalisation de l'Aeronautique et de l'Espace (BNAE). (AECMA and BNAE, along with other standards organizations in Europe, all reside in a rather complex organizational chart that has the International Standards Organization [ISO] at the top.)
The advanced development and split acceptance of the two fiber optic connector designs almost resulted in a dual ARINC standard comparable to the copper wire standard. But not quite. While AEEC's fiber optics working group made the LuxCis connector design the ARINC standard, it also added the ELIO connector design in the 801 standard's appendices, as a convenient reference, to accommodate the operators of the A380, according to Martinec.
Will an unadulterated fiber optic connector standard, with no appendices to accommodate a second design, ever exist? It can if it is made in advance of future major programs, beyond the A380 and Boeing 787, which will use the ELIO and LuxCis termini, respectively.
And that's exactly what is planned by the newly created Fiber Optics Subcommittee. The subcommittee, the Society of Automotive Engineers (SAE) and other agencies are looking ahead to a standard based on the next generation of fiber optic cable and connector.
ARINC 801 and EN4531 are based on multimode designs, which accommodate a single wavelength. However, on the horizon are single-mode designs that will support wavelength division multiplexing (WDM) to allow multiple wavelengths, instead of just one, to be transmitted on a single fiber. Single-mode cable does not disperse the light so much as multimode cable does. Another benefit of single-mode cable using multiple wavelengths is a transfer rate that is much greater than the 10 to 40 Gbits/s attainable with today's multimode fiber optics---possibly in the range of terabits/s per fiber.
More work must be done to make WDM fiber optics practical on aircraft, Martinec adds. For example, connector alignment is more critical with the smaller, single-mode cable, leaving less room for connector alignment error.
As the demand for broadband data transmission gains momentum, however, a WDM fiber optic solution is sure to be installed in future aircraft designs. And when it does, a single ARINC standard--and perhaps a single International Standards Organization standard, requiring unanimous acceptance by every standards agency--probably will be on hand for application.
At A Glance
To simplify product support, airlines seek simplified standards. Regarding cable and connectors, the evolution toward a standard based on a single design has been progressing as follows:
ARINC 600--has become a dual standard for copper wire and connectors, based on both the quadrax and twinax cable designs.
ARINC 800--has become a single standard for fiber optic cable and connectors. It is based on the LuxCis design, but includes the ELIO design in the appendices.
ARINC XXX--would cover the next generation of fiber optic cable and connector. The desire is to have it cover one design only.
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