HASS Testing: Using Pickering’s PXI and LXI Switching Products in an Automated, Highly Accelerated Stress Screening Test Solution for Three Avionics PCBs in Parallel

The Customer:

TBG Solutions TBG Solutions is a national UK test, measurement and control business. TBG works with customers to understand their requirements and, on identifying the principle challenges, engineer robust solutions that combine hardware and software. The company has delivered over 300 successful projects over the past 15 years and has maximized the use of technology to meet its customers’ ever changing demands.

“Our team decided on using Pickering Interfaces’ PXI & LXI switching products in this test system as they provide both flexibility and maintainability so we will be able to take advantage of them both now and into the future.” - Steve Bale, TBG Solutions

The Application:

Manufacturing flaws and reliability problems can cause mission-changing and even catastrophic or fatal consequences, as well as significant financial penalties, in the avionics defense industry. To mitigate these problems, original equipment manufacturers are required to perform highly accelerated stress screening (HASS) testing to ensure on-going product quality and reliability by exposing latent defects in components and assemblies. HASS testing is a form of product stress test designed to improve reliability by characterizing failures and using the information to improve the design or manufacturing process. Temperature and vibration cycling are commonly performed during the HASS testing process.

TBG Solutions needed to develop a solution to test three avionics remote input/output printed circuit boards (PCBs) simultaneously. This necessitated performing multiple procedures per Unit Under Test (UUT) in parallel, each having 500 test points encompassing a wide variety of signal types while situated in a HASS chamber. The previous test system, which was GPIB and VXI based was just too slow to get the results needed in a timely manner.

The Solution:

TBG Solutions worked closely with Pickering Interfaces, who specializes in providing modular switching solutions for use in automated production test and measurement solutions, to design a fully automated test system that utilizes Pickering’s PXI and LXI switching products.

This test system performs 50,000 electrical tests, including voltage, resistance, current, capacitance, frequency, phase, and trip, on three parallel units residing in a HASS chamber. The test system generates and executes HASS profiles and operators can exclude or include specific tests and adjust temperature and vibration levels and ramp rates. The fully automated parallel testing involves aircraft simulation, a two-part firmware download, highly accurate capacitance measurements, and load trip testing.

TBG Solutions designed and built the complete system using CAD and computer-aided manufacturing, and controlled it via National Instruments’ LabVIEW and TestStand. They decided to utilize a Pickering 18-slot LXI Chassis (model 60-103B-001) incorporating a full suite of Pickering’s PXI switch modules, including high power, matrix, and RF switches, along with three Pickering LXI Matrix modules (60-551-024 256X4) with Built-In Relay Self-Test (BIRST) in order to facilitate extremely accurate, flexible and easy-to-perform measurements. TBG created an interface driver for each instrument within the system, and the commonality within the Pickering software API allowed them to combine these drivers and other components together seamlessly to create flexible test sections that could then be sequenced on the fly. TBG took advantage of switch parallelization to test the three units as a batch, starting and ending the testing simultaneously.

Using Pickering’s PXI and LXI Switching Products in an Automated, Highly Accelerated Stress Screening Test Solution Figure 1. Pickering Interfaces’ 18-slot LXI Chassis with PXI Switch Modules and their LXI Matrix Module

Figure 1 shows the Pickering’s PXI and LXI switching products designed into the test system. Figure 2 below shows a CAD image of the TBG test system, with the PXI chassis and LXI matrix modules hidden behind a panel accessible from the rear of the two-bay 19-inch rack.

TBG Solutions HASS Test System
Figure 2. Test Equipment Rack CAD Image

Test System Benefits:

The test system not only tests three units in parallel but also brings the individual single-unit test time down from three hours to 45 minutes. This decrease in test time means a 12X increase in test throughput - significantly reducing costs for the manufacturer and, ultimately, the end customer.

Using system software tools, operators can change test sequencing, looping and HASS parameters such as vibration level, temperature level, and respective ramp rates. Operators can create a specific test profile to replicate a real-world fault on a particular component. Using system flexibility, operators can perform diagnostics, debug testing and R&D.

Conclusion:

Pickering Interfaces provided a range of switching modules with such flexibility and ease-of-use that the test system developers and designers could focus on the best way to perform tests on the UUTs rather than designing complex interconnection harnessing and circuitry. By using Pickering’s PXI and LXI switching products, the TBG team was able to provide a test system that combines high flexibility and reliability with low maintenance that will serve the end user long into the future. Pickering’s BIRST diagnostics assured the user that the signal switching was working correctly allowing for accurate testing.

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