Connectors for Aerospace – It’s All About Standards and Performance

It is no secret that manufacturers in the aerospace sector are at their most demanding when it comes to the electrical and electronic interconnection industry. As with the military sector, the choice of aerospace connector and how it is used is hugely influenced by standards and approvals, traceability and overall performance as well as the obvious weight and space saving considerations. Although fake connectors in this mission critical sector are not common, buyers and specifiers know that they must only source their products from accredited makers and suppliers.

Modern military and commercial aircraft utilise a vast amount of critical electrical and electronic systems for the purposes of monitoring and flying the plane, managing the engines, providing communications, and so on. In parallel to these are less critical applications such as in-flight entertainment. In total, these system installations mean many hundreds of connector devices are needed within every airframe.

Airplane manufacturers and, more recently, the space industry have had a significant influence on the design and performance of connectors. The circular connector was “born” in the 1930s when a leading plane maker commissioned a connector manufacturer to develop a high-performance multi-pin connector solution. The derivatives of this design are today in use across many non-aerospace sectors where the application demands a reliable connection in the most difficult of environments.

8D/MIL-DTL-38999

The most prevalent circular connector format throughout the aerospace industry is 8D / MIL-DTL-38999 [pictured top]. These are threaded coupling connectors which are available in a wide range of shell materials like aluminium, titanium, composite and stainless steel, and they are supplied in different finishes including RoHS compliant, black Zinc Nickel and Zinc Cobalt plating.

The availability of different shell materials provides the user with the option to choose a connector for applications like aerospace where weight is clearly a concern. To give you an example, a size 15 connector with a stainless steel shell weighs 58.8g while one with a titanium shell weighs 33.9g, a weight saving of 42%. Things get even lighter with an aluminium shell at 20.35g – 40% lighter than titanium – while a composite shell at 14.30g comes in at 30% lighter than aluminium. Since these connectors are used in their hundreds some serious weight saving is possible. And, because a considerable range of different fluids are used throughout the aerospace sector -  mineral and synthetic hydraulic fluid, de-icing fluid, cleaning fluid, extinguishing fluid and of course JP5 - high resistance to these types of fluids is another reason to choose 8D/38999 connectors.

The 8D/38999 connector is also a very versatile option. Aside from the extensive variety of sizes, materials and finishes, customers are able to specify contacts to suit the application. Potential contacts that we supply include signal, power, high power, coax, triax, quadrax and Elio fibre optic. This means our customers can “build” connectors to their own specification from our huge connector and accessories inventory. The connectors are manufactured by Souriau for whom Lane is an assembling distributor.

8D / MIL-DTL-38999 derivatives [some of which are pictured below] are also available and greatly extend the range of use for these connectors. Derivatives range from reinforced and hermetic sealing, to clinch nuts to ease assembly and on to double flange versions that can handle serious levels of vibration.

To complete our 8D Series / 38999 solution we offer a range of connector accessories including lightweight plug and receptacle caps and gaskets, with a wide choice of plating options with steel wire rope or nylon cords. These are manufactured by Weald Electronics and available exclusively from ourselves.

Never an industry to stand still, a series of miniature 8D/38999 connectors – the micro38999 series – has recently been developed and is being used in many aerospace applications including aircraft cabin systems and UAVs. The Souriau micro38999 connector system provides true 38999 capability but in a smaller and lighter format for maximum weight and space saving.

Rack and Panel

One disadvantage of circular connectors in some applications is the amount of space they occupy in rack and panel installations. Here, the most popular solution is the rectangular connector. Once again, standards play a great part in these types of connectors and this is best illustrated by connector systems like the ARINC 600 [pictured below]. This connector solution is widely used in avionics bays, cockpit displays, radar systems and engine management. Capable of housing up to 800 signal contacts, Souriau’s ARINC 600 compliant connector system can also accommodate power, coaxial, triaxial, filter optical fibre and waveguide connection contacts.

There are not too many manufacturers of connectors built to the standards required by the aerospace industry and we are fortunate to partner with one of the leaders, Souriau. Buyers and specifiers of components for mission critical applications are well briefed on the standards and approvals needed by the maker and the supplier. Although price is important, quality and continuity of supply is the buyer’s most important criteria.

You can view the MIL-DTL-38999 Connectors we have available for the aerospace industry here and view our Rack and Panel connectors here.

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