Two decades of avionics testing

European North Atlantic Treaty Organization (NATO) members have created the STANAG (Standardization Agreement) 3910 standard, which is an extension to MIL-STD-1553B (STANAG 3838). The STANAG 3910 high-speed data bus is used onboard the European Fighter Aircraft (EFA). STANAG 3910 (EFAbus) is a data-block-transfer bus (20 Mbps) added to and controlled through a MIL-STD-1553B low-speed line (1 Mbps). EFAbus Express (EFEx) is a newer version that integrates STANAG 3838 into STANAG 3910. Development of STANAG 3910 started in 1987 in Germany to meet the requirements for a deterministic, very high data rate, low-risk avionics bus not subject to EMI. The fiber-optic topologies can be a transmissive star, a reflexive star (EFA), or a linear bus. In many cases, hundreds of onboard Line Replaceable Units (LRUs) need to be integrated and tested during design, production, and in-service support. A mixture of data buses or networks with gateways bridging the various buses and networks is often found on airplanes.

Introducing Eurofighters

According to the EFA Consortium, the EFA Typhoon (Figure 1) is the world’s most advanced new-generation, swing-role combat aircraft on the market. It is not just a single-purpose aircraft because it has to meet the various environmental (from arctic cold to desert heat) and operational requirements of several NATO countries, replacing 11 previous aircraft types. It has been ordered by 6 nations. With 707 aircraft under contract, it is Europe’s largest military collaborative program, providing more than 100,000 jobs in 400 companies. The first prototype flight was in March 1994, and the first operational aircraft flew in July 2006. So far, more than 220 Eurofighters have been delivered. Current plans are for deliveries until 2017. Some of the EFA features are a fly-by-wire system using four redundant computers, a Flight Control System (FCS) with Carefree Handling (CFH), and Direct Voice Input (DVI).

Figure 1: The EFA Typhoon is the world’s most advanced new-generation, swing-role combat aircraft, photo courtesy of EADS, Germany
(Click graphic to zoom by 1.2x)


The Black Forest

The beautiful landscape in southwestern Germany called the Black Forest used to be a source for cuckoo clocks and barrel organs on county fairs. Freiburg, on the western slopes of the Black Forest, is now one of Europe’s top electronic clusters, known for the award-winning MicroTEC Suedwest cluster, for industrial embedded systems, inertial navigation, and digital HDTV electronics, as well as VMEbus-based avionics testers. Freiburg University, established in 1457 AD, is one of the top-ranked German universities.

Testing with AIM

AIM GmbH, Freiburg (Germany), was founded on April 1, 1989 by former engineers from LITEF (now owned by Northrop Grumman). They saw the need for test equipment for the Eurofighter project with all its new technologies. AIM developed and built the first STANAG 3910 VMEbus card and system in 1989 based on VMEbus and fiber-optics technology.

The current AVX3910-x is a fourth-generation advanced VMEbus module for analyzing, simulating, monitoring, and testing STANAG 3910/EFEX data buses used in all EFA production sites in four countries. The AVX3910-x modules provide Bus Controller, Multiple Remote Terminal Simulation, and Chronological/Mailbox Bus Monitoring functions with all modes operating concurrently on one or two fully independent dual redundant STANAG 3910 interfaces on a single VMEbus card; this incorporates full protocol error injection and detection and allows the reconstruction/replay of STANAG 3910 bus traffic.

The AVX3910-x uses AIM’s Next generation Common Core (NCC) hardware design utilizing multiple RISC processors (Xscale, formerly StrongARM). The NCC includes an onboard application support processor and multiple bus interface processors, IRIG-B Time Encoder/Decoder, deterministic timing, and a real-time OS (VxWorks, QNX, LynxOS, INTEGRITY, or others). AIM’s data bus test and analysis software for LabVIEW, Linux, or Windows offers a stand-alone protocol analyzer, a complete systems test bench, and advanced avionics integration facilities. It supports multiple AIM avionics and third-party hardware interfaces within a single application framework. Special software components are available for supporting the SAE AS4112 RT Production Test Plan and for optical testing of the data bus optical waveform.

AIM’s family of VME/CompactPCI-based High Level Bus Analyzers (HLBAs) offers flexible and modular technologies for advanced systems integration and test applications, providing real-time simulation, monitoring, display, control, and record/replay of parameters from multiple MIL-STD-1553, STANAG 3910/EFEx, ARINC429, AFDX/ARINC664, PANAVIA, Fibre Channel, and Serial I/O streams simultaneously. The HLBA is produced using “Black Forest” expertise and engineering, including handcrafted wooden shipping cases for the fully tested advanced data bus analyzer systems. Figure 2 shows the High Level Bus Analyzer for STANAG 3910 testing from AIM.

Figure 2: The High Level Bus Analyzer (HLBA), photo courtesy of AIM GmBH, Germany


The former AIM-USA was transformed into Avionics Interface Technologies, and it broadened its business base. This summer, AIM GmbH announced the establishment of their new AIM-USA enterprise with headquarters in Philadelphia, PA starting on October 1, 2010.

European events

Steckverbinderkongress (fourth year) in Wuerzburg, Germany (June 29-20) is Europe’s largest event on connectors and related technologies. I delivered a presentation on connectors that include liquid, dripless contacts as used in VITA 48.3 (mechanical specifications for microcomputers using REDI liquid cooling applied to VITA 46) and similar products.

For more information, e-mail Hermann at