SWaP-optimized instruments for flight line test and measurement

Today’s flight-line test systems are small enough to fit in a technician’s toolbox, and offer new features like Ethernet and USB interconnects, as well as data and cyber security

Perhaps nowhere else is avionics test and measurement more crucial than on the flight line. This often is the final check to ensure that aircraft weapons, navigation, communications, databuses, and other mission-critical systems are in working order. The ability to detect potential faults at the last minute can spell the difference between mission failure and mission success, and it’s up to the technicians on the flight line — on the air base tarmac or on the aircraft carrier flight deck — to perform these last important checks.

These technicians need to be fast, thorough, and well trained. Their equipment also needs to be reliable, easy to use, and work in some of the most difficult and demanding conditions imaginable: extremes of heat and cold; rain, fog, and salt spray; and in the darkness of night. How many flight-line techs tell stories about rendering military aircraft mission-ready at 2:00 in the morning during a driving rain?

The good news: flight-line test and measurement equipment represents one of the most promising opportunities for systems upgrades and technology insertion. Never a top investment priority compared to aircraft, avionics, and weapons, flight-line test gear tends to be large, cumbersome, and dated. Not only can it be difficult to use right beside aircraft — especially in harsh operating conditions — but some of these instruments also are falling behind technologically as aircraft weaponry evolves rapidly from dumb bombs to smart munitions.

The Abaco palm-sized BT3-USB-MON MIL-STD-1553 avionics databus monitor is for flight line databus test applications.

“The biggest thing driving our customers is moving away from sustaining legacy testing that was designed before the era of smart weapons,” explains Stephen Sargeant, CEO of Marvin Test Solutions Inc. in Irvine, Calif. Marvin specializes in trouble-shooting the electronic connections between aircraft weapons racks and the weapons themselves.

Sargeant makes a distinction between what he terms the “old-old,” and the “new-old,” when it comes to flight line test equipment. The “old-old,” he says, refers to antiquated test gear that’s nearly impossible to keep working, due to obsolete parts and hard-to-find batteries. The “new-old” describes redesigned test equipment that takes care of obsolescence issues, but that still has the same technological limitations of the pre-smart-weapons era, namely, an ability to check for faults in electrical signals, but not in digital data signals.

“Customers want not just to get the old made new, but want new technology to enable the best testing of smart weapons,” Sargeant says. “We can look beyond the Mk 82 and Mk 84 bombs, which are relatively dumb weapons, to JDAM [Joint Direct Attack Munition] and Small-Diameter Bomb. We can allow technicians to test functionality beyond just continuity.”

Flight line test today involves more than just testing aircraft cabling and connectors for their ability to carry electrical signals properly, Sargeant says. “Sure, you can test with that Ohmmeter to test whether that lamp will function properly, but now take an airplane with MIL-STD-1760 bus between the aircraft and the weapon,” Sargeant says. “We can test the functionality of this 1760 bus with our handheld test system, and actually emulate the weapon. We allow for the ability of the airman to test the functionality, select the test he wants to run, test whether it is properly communicating between the airplane and the weapon, and test the arm-and-release sequence prior to loading-up the weapons on the aircraft.”

The flagship flight line test instrument from Marvin Test is the MTS-3060 SmartCan, an advanced tester for pylons, launchers, bomb racks, and pods. The hand-held device is in the shape of a beer can that provides measurement, loading, and stimuli functions for continuous squib circuit monitoring, multiple load channels, audio and video simulation, and MIL-STD-1760 support.

The SmartCan is compatible with legacy beer can testers, and offers new adapters and cables to help reduce costs, improve reliability, and provide a path forward from legacy adapters and cables.

The MTS-3060 SmartCan from Marvin Test Systems is an advanced tester for aircraft pylons, launchers, bomb racks, and pods, and offers MIL-STD-1760 support.

Size, weight, and power consumption (SWaP)

One of the chief advantages to the Marvin SmartCan is its small size, weight, and power consumption (SWaP), compared to legacy flight line test gear. “Today when you look at the F-16, F-15, A-10, F-22, and F-35 military aircraft, all have different-level test equipment supporting their armament,” Sargeant says. “Now the Air Force can have the same hand-held test set across all its fighters, manned and unmanned.”

The Marvin SmartCan is 8.25 inches long, 3 inches in diameter, has front and rear panels that measure 3.5 by 3.5 inches, and weighs 4.2 pounds — just right for a flight tech’s toolbox. The SmartCan kit adds adapters, cables, and case, and weighs 35 pounds.

Abaco Systems in Huntsville, Ala., offers the palm-sized BT3-USB-MON MIL-STD-1553 avionics databus monitor for flight line test and measurement applications. It interfaces by USB port to laptop computers and oscilloscopes to provide flight techs with just the equipment they need, rather than provide large integrated test and measurement gear.

The 1553 databus moves data at 1 megabit per second — relatively slow for today’s standards — and is designed to send digital instructions to aircraft control surfaces, weapons, and other flight- and mission-critical subsystems. It’s ubiquitous, has been in service for decades, and should be part of military avionics for many years to come. “I don’t see 1553 going away in any of our lifetimes; it will be out there forever,” says Mike Hegarty, product line manager of databus products at Data Device Corp. (DDC) in Bohemia, N.Y.

“The BT3-USB-MON plugs into a laptop with our software called Bustools 1553, and plugs into the aircraft 1553 cabling at a coupler to record and analyze databus data,” says Peter Gardiner, sales specialist for avionics at the Abaco Systems Avionics Products segment in Goleta, Calif.

When it comes to analyzing analog electrical signals, the Abaco BT3-USB-MON also plugs into an oscilloscope to help technicians see rise and fall times, zero-crossing point violations, and message timing. “If the problem is in the cabling infrastructure, that can change the 1553’s characteristics,” Gardiner says. “This is easy to use on the flight line, and is a monitor-only device so it is very simple, and priced so we can see this in the tool kit of an avionics technician.” The BT3-USB-MON is designed to be rugged to withstand drops onto concrete by flight maintenance personnel.

The Abaco device is a simple and straightforward databus monitor. “To sniff 1553 data, you don’t need a high level of functionality,” Gardiner says. “You just want to listen to the data, look at the data in real time, be able to record this data, and then analyze this data offline to look at and assess what’s happening in the data.”

DDC’s Hegarty says flight line test equipment is following a trend like computing equipment “as things get smaller, lighter, faster, and in portable computing platforms as COTS building blocks.”

Future trends in flight line test equipment are extending beyond 1553 to higher-speed data networks like Ethernet, experts say. “On the military side, 1553 is old technology; it’s been around since the 1970s,” says Abaco’s Gardiner. “There are new communications protocols all the time, and it’s highly likely that flight line test equipment will move to Ethernet. I see a parallel set of tools that will emerge for those kinds of applications,” he says. “There is a need, because you must be able to support these products in the field at the flight-line level.”

The Marvin Test MTS-3060 flight line test system can operate on a variety of combat aircraft, including the F-16 jet fighter and the A-10 ground-attack aircraft.

Logistics and flexibility

Today’s flight line test equipment is capitalizing on modern computer technology to offer advantages above and beyond SWaP. Marvin’s SmartCan test system, for example, can accommodate several different software profiles that represent different weapons and aircraft to enable one system to handle a wide variety of test scenarios.

“We have loaded multiple airplanes with their weapons into one of our test sets, and have deployed with one test set loaded with as many as four aircraft, and have tested all the weapons they carry,” says Marvin’s Sargeant. “We haven’t maxed the can out yet. The software is how we adjust adding additional aircraft, matching the steps of the test to how the airplane talks to the weapons and back.”

In addition to software, Marvin designers are using field-programmable gate arrays (FPGAs) to enhance the SmartCan’s utility. FPGAs, Sargeant says, “offer a lot of flexibility, and help us miniaturize the size and logistics footprint down to handheld size, and provide very ruggedized flight-line-qualified packaging.”

These advantages extend to maintaining advanced military aircraft when they are away from their home bases on extended deployments. Modern test equipment typically is small enough to move easily to new facilities where maintenance personnel might not be familiar with newly arriving aircraft, Sargeant points out. “DOD [the U.S. Department of Defense] is looking to reduce the total cost of procurement, sustainment, and ownership of test equipment,” he says.”

This also can help lighten the burden of training for aircraft maintenance technicians. “Part of smaller and more interoperable test equipment is ease of training,” Sargeant points out. “If you are an Air Force armament maintainer on the F-16, you will have new equipment requiring more training when you move to another aircraft. But if you train on the SmartCan, you can switch airplanes and not have to be retrained. Just select a different airplane on the SmartCan, and you’re ready.”

The compact Avionics Interface Computer (AIC) from Data Device Corp. is a small-form-factor computing box with avionics-specific I/Os that can function as a router or gateway, as a flight-line tester, or as part of a flight-line test system.

Data security

Increasingly, flight line test technicians need the ability to separate classified and unclassified data as they test for the integrity of aircraft information and communications links. DDC is partnering with data security specialist Tresys Technology LLC in Columbia, Md., to enable separation of so-called red and black data, Hegarty says.

“They have a data diode, where you have secure and unsecure networking, and this controls what information flows from the secure to the unsecure network,” Hegarty says. “We are manufacturing a system in partnership with them that does this in a 1U form factor rackmount server setup. We have the capability to apply their algorithms to our equipment, like the Avionics Interface Computer (AIC) — a small-form-factor computing box that people can use to host all kinds of applications,” he says. “It has avionics-specific I/Os, and people can use it as a router or gateway, as a flight-line tester, or as part of a flight-line test setup.”

There is more to data security than separating red and black data, however, and avionics test and measurement experts are extending their expertise to include future cyber security threats like software malware and other kinds of data corruption.

Cyber security

“There is a lot of activity related to cyber security,” Hegarty says. “In flight line equipment, that is one area of vulnerability because it does offer potential paths to introduce threats in systems, and that is a major concern. A trend is more cyber-secure and cyber-aware solutions going forward.”

Any time that aircraft avionics systems connect to a USB thumb drive, laptop computer, the Internet, or any other outside data path poses the potential for infection from computer viruses, worms, or other malware that could corrupt or steal data, or even enable an adversary to take control of the system. “The threat of cyber attacks, and the need for cyber security to defend against them is huge,” says Marvin’s Sargeant.

One way Marvin defends against cyber threats is providing no connection between the SmartCan and the Internet. Plus, the latest version of the instrument has built-in cyber security. The device also has a removable SD memory card that users physically can lock away, if necessary.

The SmartCan “can do all the work, like downloading test logs, from a stand-alone computer system,” he says. “The interface has been USB. That is still available, and some customers are saying they need to block USB and add Ethernet, which is less susceptible than USB to malware attacks.”