Avionics Digital Edition
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Avionics Test Equipment: Challenges Ahead

What equipment providers are doing to keep up with new tech on today’s airframes.

Today’s avionics testers are addressing the needs of complex boxes and architectures, but challenges remain in areas such as cyber protection, fiber optics, productivity, versatility, size and no-fault-founds (NFFs).

Cyber is emerging as a big driver, said Troy Troshynski, VP of marketing and product development with Avionics Interface Technologies (AIT), a player in data-bus testing. He expects to see more of an emphasis on cyber protection from the military, especially in large depot test programs, but that “flows down to us even at the instrument level.”

“You’re taking all of these systems and subsystems off an aircraft and putting them on trays and connecting them to [test] systems,” he said. “So the first thing is, we’ve got to secure these [test] systems, so that they’re not infecting the aircraft systems.”

Avionics bus and network test instruments also need to be protected from hacking. And test data needs to be secured “when it resides in the [tester] and when it’s used and passed on to other systems.”

Troyshynski also anticipates that more testing will be done on board aircraft. It’s a question of when, not if. As avionics test equipment continues to decrease in size, weight and power, it will become increasingly economical “to have [it] become part of the actual aircraft.” As the data infrastructure — aircraft network connectivity — advances, at “some point soon both of these trends will converge and the benefits … will outweigh the costs.”

Operators also are keen to reduce the NFF problem, which stresses the repair pipeline and creates uncertainty as to which boxes are really good. NFFs cost airlines $250,000 per aircraft per year, said Ken Anderson, CEO of Universal Synaptics, a provider of intermittent testers. For a large fleet, that’s a loss of about $40 million a year, he added. Anderson also cited a 2015 statement by a former deputy assistant secretary of defense that NFFs were costing the services more than $2 billion a year.


Given the looming technician shortage, in coming years there will be fewer people on the ground to keep airplanes in the air, said Lew Wingate, VP of distribution and ground support test equipment for Barfield. “They will need easier, faster and more cost-effective equipment” in order to meet key productivity and NFF targets.

AIT’s portable data loader.Photo courtesy of AIT

One step along that path is a recent upgrade to the tablet-based remote controller of the company’s DPS1000 air data test set equipment, allowing technicians to access component maintenance manual and aircraft maintenance manual documentation. Barfield also has partnered with Universal Synaptics to distribute the latter’s wire-bundle and box-level intermittent fault testers in the commercial market.

“As much automation as possible” is a good thing, along with removing “Murphy” from the equation, said Scott Brooks, director of avionics solutions at Pentastar Aviation. Automation has improved functions such as air data test, removing the possibility of damaging an aircraft’s altimetry and airspeed sensors if the test equipment is used incorrectly, he added.

Air data test rival, ATEQ Aviation, also features tablet-based wireless control. Patrick Brousseau, ATEQ’s sales manager, said the company’s ADSE 650 product is at least half the size of other units. The tablet “connects” to a wireless transceiver built into the instrument, but it’s not using the internet.

The next big change in this niche will come when aviation moves to digital sensors, he said. “But I would not even imagine 10 years being enough time” for the industry to get to that point.

Brousseau also noted a coming mandate regarding tire pressure monitoring systems (TPMS). ATEQ, which is big in automotive TPMS tooling, has had preliminary conversations with OEMs, he said. EASA expects its TPMS regulation to materialize in 2020.


The ADS-B Out mandate continues to ring up sales for related testers. But the increasing installation rates of in-flight entertainment and communications systems has also driven demand for associated test equipment, said Astronics Ballard Technology President Jon Neal.

Pentastar said it recently acquired an Aeroflex/Viavi Solutions IFR6000 multifunction ramp tester, a portable transponder tester that can be used for ADS-B Out, DME and TCAS/TIS.

Viavi continues to improve its “ADS-B Integrity” software application, which uses the IFR6000/6015 and IFF-45TS in conjunction with its GPSG-1000 satellite simulator “to allow full verification of the ADS-B installation on the ground,” said Guy Hill, director of avionics test products. He said customers also want more versatility. “These days, it can be difficult for our customers to get approval to purchase capital equipment, so when a customer can buy one tester that accomplishes what two testers used to do, that’s good.”

Multifunctionality, however, can be a mixed bag, Brooks said. “While multifunctional [automated test equipment (ATE)] can boost productivity and reduce training costs, the equipment is somewhat expensive,” he said. This could impact the capacity of smaller shops that don’t have the budget to own two units if the ATE incurs damage or requires calibration and there is no backup unit. Neal agrees that factors such as reliability, longevity, ease of use and overall value are the most important considerations.

Teradyne’s VERTA can check optical power levels at all sending and receiving ports of units under test (UUTs) to isolate faults in the boxes’ optical transceivers.Photo courtesy of Teradyne

Neal also points to the increasing accessibility of data about the health of avionics units while they are still on aircraft via systems such as aircraft interface devices (AIDs), equipment that’s manufactured by Astronics and others. Products like the AIT portable data loader, which can upload software updates and download data from systems such as engine controllers at the same time, can also speed analytics.

Obsolescence, however, remains a problem, Hill said. “Some test equipment has been in the field for … 25, 30 or even 40 years and … [some] components … can no longer be sourced.”

Fiber Optic Challenges

The military’s gradual move from copper- to fiber-optic-based avionics communications in areas such as radar and electronic warfare also poses challenges. One problem is that components such as optical transceivers, which convert optical signals into electrical signals and back again, age more rapidly in an environment with high shock and vibration levels as well as temperature extremes. The components may start to fail in subtle, hard-to-detect ways.

In addition the amount of optical signal that’s available on the receiving end — after accounting for losses in transit — may be a “very narrow margin,” said Tony Erwin, product manager with Teradyne’s Defense & Aerospace Group. “We feel it’s very important to be able to tell diagnostically what’s going on.”

The company’s new optical tester/switch matrix, VERTA, can check optical power levels at all sending and receiving ports of units under test (UUTs) to isolate faults in the boxes’ optical transceivers. The LXI-based depot-style tester pre-integrates high-density switching — between avionics boxes and test instruments — optical power meter, and optical attenuator functions into one piece of equipment, something that’s unique in the ATE industry, Erwin said. (LXI stands for LAN eXtensions for Instrumentation.) It can also be forward-deployed on an aircraft carrier or used in factory test, he added. At the same time that it’s testing optical parametrics, VERTA sends the optical data stream to multiple data bus-test instruments that are connected to the UUTs. The test instruments can stress-test communications protocols, such as Ethernet and Fibre Channel, to see whether something is amiss at that level of the architecture.

It’s important to test optical parametrics and bus functions simultaneously, Erwin said, because it simulates real-world network operating conditions “by margin-testing optical transceivers across the full operating power range while communicating to the UUTs” via their own bus/network protocols. Overall test time is also shorter. VERTA can measure average power within plus or minus 1.1 dB accuracy, he said.

Here’s an example of where VERTA would shine: Box A is talking Ethernet to Box B, and everything seems fine. But there are underlying issues related to optical signal loss, which a functional test may not identify. Communications, for example, may be going through a lot of retries. Such a problem is traceable to the attenuation of the transmitted signal, either because of degraded output power from Box A’s transceiver transmitter or degraded sensitivity in Box B’s transceiver receiver, Erwin explained.

Intermittent Fault Testers

Universal Synaptics’ Voyager Intermittent Fault Detector (VIFD) and Intermittent Fault Detection & Isolation System (IFDIS) — both highly parallel testers — look for discontinuities in electrical wiring systems at the harness and box levels, respectively.

Voyager tests every wire in a harness bundle simultaneously and continuously, rather than sequentially, Anderson said. Once the unit finds a problem, its software engages spread spectrum time domain reflectometry to pinpoint the distance to a fault. Voyager scales from 128 to 256 to 512 test points.

IFDIS tests wiring in the backplanes of avionics boxes. Universal Synaptics is poised to deliver a 10,240-test point system to the Naval Air Systems Command, Anderson said. Though that might sound like overkill, the density of today’s buses and networks — wired through the backplane — requires commensurate density in real-time circuit monitoring equipment. The system can scale to a maximum of 20,480 circuits without any loss of detection speed or continuous monitoring, he said.

It’s important to monitor all circuits simultaneously, he said. If you look at only one wire at a time, the fault “has to align perfectly with the scanning measurement window,” an unlikely event.

The company said that both Voyager and IFDIS can detect and isolate problems in all three stages of intermittent fault development. Stage 1 encompasses random, low-level, nanoseconds-duration “micro-breaks” that are difficult to detect and may not manifest themselves operationally. Stage 2 includes circuits that fail intermittently in operation yet pass ground tests and circulate around the inventory as NFFs. Stage 3 includes hard failures such as the opens and shorts that traditional ATE is designed to detect.

The equipment can sniff out intermittent events as short as 50 nanoseconds in duration, he said. AVS