NTS News Center

Latest News in Testing, Inspection and Certification

NTS News Center - Latest News in Testing, Inspection and Certification

FAA Fire Testing at NTS

FAA Fire TestFire and flammability testing is required for products used in a wide range of industries, NTS fire and flammability testing services typically fall into two categories: 1) ignition and flame spread, and 2) fire resistance. The Federal Aviation Administration calls out a number of standards NTS conducts testing to for our aviation customers.

FAA Fire Testing Specifications

  • RTCA DO-160 Section 26
  • ISO 2685
  • FAA AC20-135
  • FAA Powerplant Engineering Report No. 3A
  • FAR Part 25

Meeting these test specifications requires specialized burner equipment as well as customized fire rooms for the safety of the technicians, engineers and customers witnessing their test. The specifications call out various burn lengths, the distance from the original edge to the farthest evidence of damage to the test specimen due to flame impingement, and burn time to failure of components depending upon the component being tested, for example 60 seconds is the specification for interior compartments housing crew or passengers.

NTS utilizes liquid fuel burners, both vertical Bunsen type and horizontal (pictured above). The flame temperature for the burners reaches the required 150°F ± 2000°F (1100°C ± 80°C). The heat flux of these burners are at least 4500 Btu per hour (116 ± 10kW/m²).

Contact us today to learn more and discuss how NTS can help you with all of your safety-of-flight qualification testing! Click here to get started.

HALT Product Design and Reliability Seminar

On November 10, 2017  join engineers and technicians from our NTS Chicago facility as they host an all-day, interactive seminar on HALT (Highly Accelerated Life Test) covering the basics, benefits and how it can help you determine your product’s reliability. Additionally, they will introduce other available tools designed to prevent early life-cycle product failure (e.g. HASS – Highly Accelerated Stress Screening) as well as share with you, answers to some of the most frequently asked questions on product reliability testing.

The seminar will run from 9:00 am to 3:00 pm at our Chicago, IL facility. Click here for more information and to register!

Fuel Icing and Contamination Test Stand Goes Live in Santa Clarita

NTS understands the significant threat to aerospace fuel system components posed by ice and contamination, and that is why NTS Santa Clarita has just completed significant upgrades in its water in fuel, fuel icing and contaminated fuels testing capabilities.

Our novel, stand-alone, water in fuel/fuel icing test stand is equipped to perform testing in accordance with SAE ARP 1401 and MIL-F-8615D on aerospace fuel system components sub-systems and systems, along with our neighboring test stand designed to run contaminated fuel testing in accordance with MIL-F-8615D and SAE ARP-8615.

Our enhanced capabilities allow us to support aerospace fuel system component and/or system testing (including aerial refueling components and systems) with flow capabilities up to 500 gpm at 200 psig.  NTS’ design allows for the ability to perform both recirculated and single pass testing.

Fuel Icing / Water in Fuel Testing

Simply stated, water buildup within aircraft fuel systems becomes ice during changes in altitude, and changes in fuel demand can knock loose this ice, creating significant hazards to fuel system and engine components.  NTS replicates these conditions by injecting a known amount of water into the fuel, then cools the mixture to the required temperatures and flows through the test article.  The mission profile (e.g. Idle, Takeoff, Cruise, Descent, and Landing) is then performed at three temperatures, each representing a different physical state of ice with its own associated failure mode and samples are taken throughout the system to verify the water content meets specified requirements.

Contaminated Fuel Testing


Whether at a commercial airport or the most remote military airfield, contaminants can find their way into a fuel farm and into a plane’s fuel system.  These contaminants have the potential to cause parts to fail over time, whether through wearing out O-rings and seals, or jamming moving parts.  NTS’ test system is designed to test fuel system components’ resistance to failure due to these contaminants by injecting a defined amount and mixture of contaminants into the fuel stream or reservoir and sending this mixture through the test article.  The mission profile is then performed and leakage testing conducted to determine the performance outcome.

These state of the art capabilities, and our partnered approach to testing, uniquely positions NTS to provide you with the testing solutions you need to go to market with confidence. To learn more about the testing capabilities at NTS Santa Clarita, contact us today!

Love that muddy water? Slurry Testing at NTS Detroit

Slurry testing is a specialty at NTS Detroit testing laboratory. It is a great way to gauge the durability of products at the risk of failure due to various environmental operating conditions. Commonly used in the automotive industry to test rotating components such as motors, alternators, and bearings, slurry testing implements the use of one of our mud slurry test rigs or fabrication of a custom test setup to expose your product to the different environments it would encounter during end-use.

Slurry Testing Dana Inc

Also referred to as mudsplash testing, mudbath testing, mud resistance testing, or muddy water durability testing, it is a fast and consistent method to determine things such as overall durability, seal quality, or leakage. This testing can be done at specified temperatures, for various durations, using any combination of mud, salt, or dust, and with radial and/or axial load applied. It commonly goes hand in hand with dynamometer testing. We can also determine if a component can maintain its original properties during exposure to slurry, such as its ability to dissipate heat. A unique test we offer exposes prop shafts to hot/cold, salt/sand slurry, and torque/speed, all while monitoring the bearing temperatures with infrared cameras.  Our expertise encompasses nearly every aspect of a vehicle’s drive train including Hybrid and EV.

Some specifications that call out slurry testing include ISO16750, Continental Spec CS11982, and Ford Laboratory Test Method FLTM BI 168-01.

Click here to discuss this and other automotive testing needs with our experts!

What is Climatic Testing?

Ingress Protection

Ingress Protection testing at our Montreal, QC laboratory.

Climatic testing is a type of environmental stress testing that recreates in a controlled setting all environmental/weather conditions a product could conceivably encounter. This is done not only to ensure compliance with any applicable regulatory standards, but also to determine the reliability of a product and its potential longevity. Products that undergo climatic testing will perform more reliably and be easier to bring to new markets.

NTS’ extensive climatic testing capabilities give manufacturers an accurate picture of how their product will perform in any environment. Our engineers can design a testing program that meets your requirements. Contact our office directly for assistance.

Types of Climatic Testing

Climatic testing is a broad category covering a range of simulations and testing programs. It may include:

  • Temperature and humidity testing: NTS performs temperature and humidity testing in a variety of chambers to accommodate products of any size. We can provide static testing at a constant temperature/humidity level or thermal cycling to determine how a product reacts when exposed to rapid environmental shifts. Thermal cycling is frequently used to measure the reliability of a solder joint. Static testing, or steady state testing is often used to determine high and low ground survival temps when testing aerospace equipment.
  • Corrosive atmosphere testing: Salt spray and salt fog testing measure the ability of protective coatings and electronic components to withstand corrosive environments. For this type of testing, we use a sealed chamber in which a product or component is exposed to an atomized sodium chloride solution. One of the more common tests we perform involves subjecting a product to a 5% salt solution for 720 continuous hours, ensuring compliance with ISO 9227:2012 standards.
  • Sand and dust testing: Sand and dust testing is especially important for electronics used in military ground vehicles and other delicate applications. In our facilities, we can test components as large as 8 ft3, simulating winds up to 40 mph and temperatures in excess of 200˚F. Using the results of these tests, our clients can produce reliable ruggedized components that meet the MIL-STD-810 standard. We can also perform dust explosion testing to OHSA, NFPA and other standards.

Other tests we provide involve wind and rain, hail impact, solar radiation, altitude and other simulations. We can combine our testing programs with shock and vibration simulation for a more accurate picture of the real-world conditions your product will face. Contact one of our engineers to explore your options.

Benefits of Climatic Testing

Climatic testing is often a requirement when bringing military, aerospace and other components to market. Testing is also essential for demonstrating that your product meets end-user expectations. For example, through climatic testing, manufacturers can determine a product’s high and low operating temps. By sweeping through a wide range of climatic conditions, it’s possible to pinpoint specific failure modes, reducing liability and improving overall product quality.

NTS provides climatic altitude testing for aerospace and aviation manufacturers that meets RTCA DO-160 requirements. Other standards we frequently work with include MIL-STD-202 and MIL-STD-883, as well as industry and manufacturer-specific programs for OEMs. For more information, contact NTS by submitting a request for quotation online.

 

Solar Radiation Testing in Accordance with Method 505 of MIL-STD-810

MIL-STD-810 Procedure 2 Solar TestingSolar radiation (sunshine) testing is one of the basic tests required for any military equipment planned to be deployed in the open and therefore subject to direct radiation from the solar source. The effects of this radiant energy can generally be divided into two groups or classes, heat effects and photochemical effects. Heat effects on exposed equipment can raise the internal temperatures of the equipment substantially above the ambient air temperature. Temperatures in excess of 160oF have been recorded in parked aircraft exposed to the sun while ambient air temperature was in the 90oF range. Photochemical effects of sunlight may hasten the fading of colors and lead to the deterioration of plastics, paints, rubber and fabrics. The combined effects may lead to the outgassing of plasticizers in some materials along with discoloration and a reduction in transparency.

MIL-STD-810, Method 505.5 outlines two procedures for performing the Solar Radiation test. Procedure I requires a cyclic exposure based on the diurnal cycle and is most useful for determining heating effects on exposed materiel as well as materiel enclosed within a container. Procedure II is a steady state (non-cyclic) exposure most useful for evaluating actinic (photochemical) effects of ultraviolet radiation on materiel since it represents an accelerated test with a factor of 2.5. Because Procedure I is more akin to a natural cycle and does not have the acceleration factor of Procedure II, it is not an efficient cycle with which to evaluate long term exposures. Therefore, when it is used mainly to evaluate the direct heating effect, Procedure I can be performed with source lamp arrays emitting less than the full solar spectrum. Procedure II however, demands full spectrum sources emitting light in the ultraviolet range if the total effects of long term exposure are to be properly evaluated.

The solar light spectrum has been accurately measured over the wavelength range of 280 – 3000 nm as well as the power distribution within this range, and it is this range that we would seek to reproduce in the Solar Radiation test.  Reproducing this entire range using lamp sources however can be quite challenging. Sources emitting ultraviolet wavelengths between 280 and 400 nm tend to be quite costly and their performance deteriorates quickly. Some of the MIL-STD recommended sources such as xenon arc and carbon arc fall into this category.  In fact, it was reported that the first commissioned sunshine test facility in 1945 fell short of the contract requirements due to several deficiencies, one of which was the amount of UV that could be produced at the test item. Cost and reliability issues are why many test labs have chosen to perform only Procedure I  with source lamps covering the visible and infrared spectrum range of 400 – 3000 nm (0.4 – 3.0 µm).

Reproduction of the required environment for the Solar Radiation test requires a chamber space in which the ambient air temperature and airflow over the test item can be controlled as well as a solar light source which may consist of a single source in the case of arc-type lamps or a multiple source array in the case of metal halide or incandescent type lamps. The distance of the light source from the test item may be varied to achieve the required irradiance. Airflow over the test item can significantly impact test results. When MIL-STD-810D introduced the “cycling for heat effects” (Procedure I) the guidance for airflow was to use airflow as low as possible consistent with achieving satisfactory control of the ambient air temperature at the test item or between 0.25 and 1.5 m/s (50 to 300 ft/min). The current guidance from MIL-STD-810G has changed for procedure I to 1.5 to 3.0 m/s (300 to 600 ft/min) in recognition of better field data. The requirement for peak radiation intensity at 1120 W/m2 has changed little over the history of the Solar Radiation test although there have been slight changes to the spectral energy distribution based on updated measurement techniques of the actual solar source.

When the primary concern is testing for heat effects, the question is often asked why an oven or chamber test for enclosed equipment could not be used in place of the Solar Radiation test.  The primary reason is that ovens and chambers transfer heat from a uniform ambient atmosphere surrounding the test item, whereas the solar test transfers heat through direct radiation. The directional effect of radiant heating produces temperature gradients through the test item that are not replicated in ovens or temperature chambers.

When a Solar Radiation test is required,

  • Perform the Solar Radiation test prior to the High Temperature test, as the product temperature measured in the solar chamber may need to be used as the ultimate high operating temperature for the product.
  • Consider the orientation of the test item within the solar chamber so as to replicate the in-use conditions with respect to both the direct radiant light energy and the airflow direction. This will affect both the temperature gradients and any cooling effects provided by the airflow.
  • When testing to Procedure I, remember that several consecutive cycles will likely be required for the product to achieve the ultimate high operating temperature for the most critical area of the test item to be within 2oC of the previous cycle. This usually means 3 to 7 cycles.
  • If operation of the test item is required, operational times will need to coincide with the peak response temperature of the test item in each cycle which will not coincide with the peak radiation intensity.

How can I relate the results of MIL-STD-810 salt fog testing to the life time of my product?

This is a very common question that we get asked quite often and unfortunately there is no correlation between what the product sees in the salt fog chamber to what it will experience out in the field. In order to understandSalt Fog Testing why, you must first understand the purpose of the test.

Originally stated by V.J. Junker in The Evolution of USAF Environmental Testing(1), the test is to determine the resistance of aerospace ground and aerospace equipment to the effects of a salt atmosphere.

According to Mil-STD-810G, the test is performed to determine the effectiveness of protective coatings and finishes on materials. The stated purpose of the test is to determine design flaws such as dissimilar metals, improper coatings, uncoated materials, electrolytic action, binding of parts, etc. Therefore, results can be related to the suitability or quality of parts or assemblies, but cannot be directly related to exposure time in the marine environment.

Salt Fog and Salt Spray testing are conducted at 14 NTS locations across the country. Visit our locations page to find the lab closest to you!

(1) Junkers, V.J. The Evolution of USAF Environmental Testing, Technical Report AFFDL-TR-65-197, October 1965.

Breaking Ground at NTS Chicago!

New NTS Chicago FacilityWe are pleased to announce that work has started on NTS Chicago’s new facility in Mount Prospect, Illinois. Opening this summer, the new location will accommodate the aggressive expansion of our capabilities to include advanced electromagnetic compatibility (EMC) testing, additional environmental simulation and enhanced reliability testing.

This purpose-built, 40,000 square foot site will perform the full suite of testing for the automotive, avionics, aerospace, military, commercial, medical and industrial markets, to name a few.

Enhanced capabilities will include a large-format semi-anechoic chamber for emissions measurements, an assortment of EMC chambers for testing and troubleshooting, additional environmental testing offerings such as blowing sand and blowing dust, expanded ingress protection, increased capability for corrosion testing and expanded capacity for many of our current high-demand tests such as HALT and vibration.

These capabilities, when added to the existing list of services offered out of our Rockford facility, will give us the strongest presence of any test lab in the region. We look forward to sharing the progress of this build with our customers and anticipate inviting everyone to an open house when the weather is warmer this summer!

 

Ensuring the Reliability of Products with Environmental Stress Screening

ESS is a series of tests aimed at the identification of potential manufacturing flaws. By utilizing more intense versions of temperature and vibration test methods, ESS is able to accelerate failure at weak points. This allows manufacturers eliminate units more likely to fail and ship only the highest quality products to customers.

Manufacturers are achieving significant gains in reliability through Environmental Stress Screening (ESS).

Test methods including vibration, thermal cycling, and thermal shock are utilized to run the equipment under test (EUT) through an accelerated profile. , manufacturers now can run the final product through an accelerated profile to prove out its ability to endure its intended environment and life span.

Thermal shock testing and thermal cycling are two methods used to accelerate product failures, especially for products which are intended for use in environments where extremes in temperature are encountered. Extreme changes in temperature may cause materials to expand, contract, loosen, over-tighten or simply fail.

Thermal Shock Chamber

Thermal Shock Chamber

The thermal shock chambers are generally dual zone chambers. These test chambers have either an elevator or a conveyor that transfers the samples being tested from one temperature extreme to the other. The low temperatures are achieved with liquid nitrogen, while resistance heating elements are used to achieve the required high temperatures. Temperatures typically range between -70⁰ C and 180⁰ C. The samples are transferred between temperatures in five seconds or less.

Thermal cycling chambers have a larger volume and are single zone. The temperature transition is achieved by turning off the heating elements and injecting liquid nitrogen. The transition is slightly slower than the thermal shock chamber, at roughly 60⁰ C per minute. Temperature ranges are typically between -70⁰ C and 150⁰ C. Typical volume of these chambers is 9 cubic feet.

Thermal cycling chambers have a larger volume and are single zone. The temperature transition is achieved by turning off the heating elements and injecting liquid nitrogen. The transition is slightly slower than the thermal shock chamber, at roughly 60⁰ C per minute. Temperature ranges are typically between -70⁰ C and 150⁰ C. Typical volume of these chambers is 9 cubic feet.

Following testing, reliability engineers are able to predict the actual life of a product in the real world

The ESS process identifies unanticipated flaws in design and discovers issues related to daily variations in the manufacturing process. Different environmental simulations bring to light specific failure modes in the product.

Some common techniques and their associated failures when used with electronic packages are:

  • Thermal Cycling: Cracked Traces, Under-Specified Components, Materials Failure, Solder Joint Failure
  • Thermal Shock: Discontinuity Due to Thermal Expansion, Solder Joint Failure
  • Vibration: Pad Delamination, Cable Interface Issues, Solder Joint Failure, Intermittent Connections,
    Materials Cracking, Nuts, Bolts, Screws, etc. Getting Sheared

Vibration testing is another useful tool in ESS testing. It is used to identify resonances in a product which can cause the product to self-destruct. It can also be used to accelerate metal fatigue failures. Fatigue testing has traditionally been performed using servohydraulic systems, which can be expensive and take considerable time to perform. Utilizing electrodynamic vibration systems can reduce test time because high frequencies can be used and acceleration levels can be increased. Vibration data can be collected in real world situations and replayed through the vibration table. This process can reduce the expense of field trials and predict design and manufacturing defects. Additionally, transportation vibration testing can be performed on the unit to determine if failures will occur in transport.

Vibration testing is performed on an electrodynamic shaker system. The shaker

Vibration Tables

Vibration Tables

can reproduce vibrations such as sine vibrations which occur on rotating machinery, or random vibration, such as that which occurs in an automobile driving down bumpy streets. The electrodynamic shaker operates like a giant loudspeaker system with frequencies limited between 5 and 3000 Hz. (Loudspeakers operate between 20 and 20,000 Hz, which is the range of human hearing.) There are numerous versions of vibration systems, but the most common is a system capable of performing vibration tests in three axes, one axis at a time. The vertical axis is done with the shaker in the horizontal position; the other two axes are done by rotating the vibration head 90 degrees and using a slip table. The photograph in Figure 3 shows the vibration table in the vertical position in the background. The slip table is in the foreground. It is a metal plate on a granite table which has lubricating oil continuously pumped between the plate and the granite to minimize friction.

HALT (Highly Accelerated Life Testing) is another frequently used test method.

Halt Test Chamber

Halt Test Chamber

HALT combines all of the above test methods. It is used to expose design defects and constraints in a product by accelerating stress levels. HALT primarily uses a combination of thermal and vibration step stresses to expose any latent weaknesses in a product. These primary environmental stresses may have additional stresses such as voltage and frequency added. HALT stresses a product well beyond its design specifications, up to the destructive levels of the product or the fundamental limit of the technology. It is a tool used to optimize product quality and reliability.

HALT testing does not have a specification, but instead uses guidelines. It is a five step process that starts with a cold step stress test, goes on to a hot step stress, followed by temperature cycling, then onto vibration, and finally a combination of temperature cycling and vibration. The test starts at room temperature and the temperature is lowered in 10⁰ C increments until the product fails. Once the product fails, the temperature is raised in increments until it recovers. This establishes a lower operating limit for the product. Then the temperature is successively lowered and raised to find the temperature at which the product fails. This establishes the lower destructive limit. Cooled with liquid nitrogen, temperatures in the chamber can reach -100⁰C. The next step is to do the same with high temperature. The high temperature can reach up to 200⁰ C. Then the temperature is cycled between the operating limits. The fourth step is a vibration step stress test in which the acceleration level is raised in 10G increments up to 60G. The vibration profile is pseudo-random in 6 degrees of freedom and is created using pneumatic hammers under the test table. Again the operating and destructive limits are established. Finally, all of the test modalities are combined.

In HALT testing the product usually, but not always, fails at each stage. It is up to the engineer to decide if changes should be made to correct the cause of the failure, depending on how the product will be used. The use of HALT testing can significantly reduce the random failure rate of a product during its useful life.

Another test which is an adjunct to HALT testing is HASS (Highly Accelerated Stress Screening) testing. Once the operating limits have been established in the HALT test, the HASS test can be used to screen products in which warranty returns increase after changes in components or production processes are made during the life of the product.

Testing can be performed on bare boards, populated subassemblies or full products, allowing focus on predetermined trouble areas. Depending on the level of reliability required, the number of test units can range from 100% to a few units from each vendor, manufacturing line or batch. Active monitoring can be used to track the shift in electrical properties as the circuits encounter the extremes of each test. If a measurement is found to be out of tolerance, a root cause analysis is conducted to determine the source of the problem and corrective action established.

The end product of all testing is a clearer understanding of how products will react in defined ranges of conditions. Once satisfactory results are obtained, manufacturers can confidently package these products and ship them to their customers.