With the introduction of high-speed data communications for the cockpit and the continuing evolution of advanced in-flight entertainment systems in the cabin, avionics connector manufacturers and standards-setting bodies working to define specifications have rarely had more on their plate.
"The aerospace industry has been blessed with a lot of requests for new connector development," said Luc Kaes, multi-signal and fiber optic business development manager with Radiall, based near Paris. "We’ve been quite busy, and over the last 12 to 18 months have seen requests for new architectures, modularity, smaller form factors, and more functions, as well as new requirements linked to higher density."
Kaes described the resultant design challenges. "Electronic components are getting smaller, so the number of inputs and outputs per square inch is increasing," he said. "Our connectors need to be smaller, with a higher density. The challenge is in putting pins closer together without interfering with electrical performance or introducing interference in the signals, and in addressing rising temperatures in the connector. So we need more simulations and to master our processes."
And then there’s the issue of cost, against which everything is judged. Said Kaes: "We’ve been hit hard by the cost of raw materials — gold, silver and copper. Our customers are asking us to find solutions to alleviate those costs. Everybody is now more careful about the types of materials being used.
"The key to avoiding the use of gold or controlling the thickness of gold is in mastering your processes," he said. "Gold and metal are also heavy and weight is a big issue with the cost of oil. So most new connectors are composite connectors. The drawback there is that it is more expensive to invest in the mold. But plastics or composites are gaining ground in replacing parts that used to be metal, particularly in the back shell."
Throw in the conductivity and grounding challenges associated with more-composite aircraft like Boeing’s 787 and Airbus’ A350, as well as environmental standards such as Europe’s REACH (Registration, Evaluation and Authorization of Chemicals) program, which requires manufacturers to identify (and eventually ban) all the toxic chemicals that go into the manufacture of their products, and the industry is spinning in more directions than the electrons passing through the connectors they make.
Trying to make sense of it all is ARINC and the subcommittees and working groups under its Engineering Standards for Avionics and Cabin Systems committees, which are working to bring standardization to the mish-mash of connectors that are now being employed to address high throughput needs.
For cabin applications, in particular, it is not uncommon to see connectors that were designed for one application being used in multiple other applications for which they were not designed.
"There are a lot of mixed approaches with mixed success with existing products," said Larry Paterson, principal technical designer with Boeing Airplane System Laboratories, who cited EMI problems when common connectors are used for high-speed applications.
"We’re seeing the use of Quadrax, which was developed for Ethernet, being used for digital video and low voltage differential signaling," Paterson said. "We’re seeing a problem in trying to adopt these connectors to other applications."
Paterson also is a member of the AEEC Network Infrastructure and Security (NIS) Subcommittee, which is defining ARINC 664 protocols to implement Ethernet on commercial aircraft. The concern extends beyond the application of the connector to the maintainability of the part, he said.
"As we see a mix of different connectors for different applications, repairs being made to those connectors could be to different standards for different places on the airplane," he said. "Shoehorning existing connectors into new applications has an effect on repairability. We want to limit the number of connector types in order to limit the complexity of connectors being maintained. All of this is active, and these are things we’ve been talking about for several years.
What’s needed, the standards developers agree, is defined systems, protocols, software, hardware and maintenance requirements for the present and coming generation of connectors.
It was just those issues that topped the agenda of the Technical Connector Working Group within the Cabin Systems Subcommittee, which met in Las Vegas in December. It was the third meeting for the working group, which had also met in Hamburg and Dublin over the prior six months.
The gigabit Ethernet connector is at the top of the list for standardization, as the major IFE providers — particularly Thales and Panasonic Avionics — are designing systems that will require gigabit Ethernet (over 1000BaseT) connectors. Connector manufacturers, including Deutsch, Souriau and Tri-Star Electronics International are developing products for gigabit Ethernet.
"We’ve been working in 100BaseT Ethernet up until now, which simply required use of a Quadrax contact," said David Gracey, an aerospace technical consultant who spent 35 years with Boeing and is a member of the Connector Technical Working Group and Cabin Systems Subcommittee. "It’s certainly possible in three to four years that we’ll need a 10 gigabit connector because of the speed at which these systems will be running."
Boeing’s under-development 747-8 Intercontinental, for example, will require gigabit Ethernet connectors, as will the Airbus A350XWB. The 787 Dreamliner uses Quadrax connects, but future versions of the aircraft will likely be enabled for 1000BaseT-and-up connectors.
"Boeing is working along the lines of the industry on a gigabit Ethernet solution as an alternative to Quadrax," said Paterson. "The argument is when do you migrate to fiber? At one point we thought that would be after 100BaseT, but there is still a lot of interest in copper.
"Fiber has several issues associated with it, including requiring airline mechanics to be pseudo telecom technicians. They would have to learn about optical sources. So fiber is good from a weight standpoint, but it has its own set of issues."
Members of connector-related subcommittees and working groups of the Cabin Systems Subcommittee discussed four different categories of connectors needing further definition: (1) those for IFE systems in first and business classes; (2) back-of-the-seat connectors for IFE in coach class; (3) connectors for the IFE passenger control unit; and (4) seat-to-seat connectors.
Manufacturing a connector for the IFE systems used in first- and business-class seats is a challenge because of the articulated arm that holds the video screen. This configuration is also used in the row behind the bulkhead and in emergency rows.
"What’s happening is a problem with the connector between the monitor and the arm because there is not much room in there for a wiring harness and it is difficult to do a gate replacement of that monitor," explained Gracey. "There is a real need to be able to do that, though, because they can’t sell a first-class seat if the monitor isn’t working."
IFE providers in some cases have clauses in their contracts with airlines that make them financially responsible for premium seats that go unsold because of malfunctioning IFE equipment.
"We need a rack-and-panel-type connector that makes it possible to lift the monitor off the arm and replace it with a new one," said Gracey. "You don’t have to mate the connector; just the act of screwing down the monitor means it is always fully mated and sealed against moisture."
The second category would be an improvement over the inexpensive D-sub connector used in the seatback. The connectors have latches that sometimes aren’t properly engaged by the technician, which leads to an intermittent connection when one comes loose. The solution, said Gracey, is a latch with a positive action like a twist so there is a tactile and audible indicator when the connector is fully latched.
The third connector issue is related to the passenger remote control unit that is attached to the armrest with a wire that pulls out of a cradle. Many of the connectors for this type of application have wires soldered to the connector.
"Boeing and Airbus don’t like solder in wiring," said Gracey. "It is impossible to fix at the gate, and, as per the FAA, you can’t use a heating device on an airplane with fuel. You need a crib contact that you can take out with a tool, strip it and put a new contact on without heat."
The fourth need, as defined by connector working groups, is for a seat-to-seat connector, which is expected to be a gigabit Ethernet connector. A daisy chain configuration is used today, but alternatives are desired because of cost and weight. A circular-type connector could be a solution here.
Avionics Magazine’s Product Focus is a monthly feature that examines some of the latest trends in different market segments of the avionics industry. It does not represent a comprehensive survey of all companies and products in these markets.
Following are some recent developments announced by connector manufacturers.
ITT Interconnect Solutions, Santa Ana, Calif., in December announced the development of a micro miniature connector capable of providing 100 signals in a lightweight, compact package. The MDM PCB connector features contact pitch spacing of 0.050 inch, providing maximum signal density for applications where board space is at a premium. It is described as ideal for applications in avionics, oil field exploration, electronic instrument packages and satellite systems. "The MDM PCB connector meets specific customer requirements for a 100-position robust, compact connector design," stated Keith Teichmann, ITT Interconnect Solutions director of marketing. "We have also integrated EMI shielding via a special back molding process, saving further space and weight on the PC board."
ITT introduced a number of other avionics interconnect systems in 2008, including the Trinity MKJ Series, a family of miniature circular connectors, in November. The new connectors are up to 71 percent lighter and 52 percent smaller than comparable devices. Other products introduced include the NDD Series, a family of high density, low-profile connectors that meet MIL-DTL-32139 specifications; and an ARINC 600 connector designed specifically for in-flight entertainment systems in commercial aircraft.
Delphi Connection Systems, of Warren, Ohio, entered into an agreement with JR Aero Services, of Cincinnati, to promote Delphi’s data-connectivity systems, including USB connectors, ports, hubs and cabling, to commercial and corporate aircraft operators.
Positronic Industries, of Springfield, Mo., in December announced that it had achieved AS9100 certification for its North American operations.
Ralph L. Phillips was appointed president of Smiths Interconnect, of Morton Grove, Ill., by parent company Smiths Group plc. Phillips, who had been acting president since May, joined Smiths Interconnect with the Smiths acquisition of TECOM Industries in 2004. The Connector Technology Group of Smiths Interconnect includes Hypertac Ltd., of London; Hypertronics Corp., of Hudson, Mass., and Sabritec, of Irvine, Calif.
Sabritec passed qualification testing of its Size 16 ARINC 801 terminus for single and multimode applications. The terminus is available both as a pull-proof design and a general use design for tight jacketed cable. Sabritec also introduced new Expanded Beam Fiber Optic contact technology designed to fit into standard size 12 cavities of MIL-DTL-38999 Series I, III and IV connectors; and a new range of High Frequency Coax Contacts for multi-pin connector applications.
A.E. Petsche Co. opened a new connector assembly operation at its Dallas headquarters. The 20,000-square-foot facility increases the company’s assembly capacity to a rate of 10,000 mil-aero connectors per day.
BTC Electronic Components, of Wake Forest, NC, signed an agreement to become a fully franchised distributor of RF interconnect products manufactured by Trompeter Electronics, Mesa, Ariz. Trompeter is a subsidiary of Emerson Network Power of St. Louis.
Radiall, based near Paris, in 2008 released the LXC-R, a single-channel fiber optic connector suitable for applications in in-flight entertainment, sensors and military radio networking. The LXC-R is qualified to withstand a high level of vibration and shock and is specifically designed to be compatible with the industry standard LuxCis ARINC 801 fiber optic termini. LXC-R products include keyed plugs and receptacles with various options for different environmental sealing requirements.