NTS News Center

Latest News in Testing, Inspection and Certification

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

Coming soon – The “Monster Machine” Massive Wave Simulator

From our underwater shot test quarry facility in Virginia to our 25 foot centrifuge in California, NTS has a tradition of “going big” when it comes to new test equipment. The engineers at our Hunstville, Alabama facility are keeping up with this tradition as they take delivery and work on the installation of their newest equipment, appropriately dubbed “the Monster Machine”.

The Monster Machine is a 20 foot tall, 32 foot wide, 16 foot deep wave simulation machine capable of supporting 30,000 pounds on a 14 foot square test table. Equipment under test will be subjected to 360 degree rotation at 6 RPM! The table can be adjusted to various radii enabling the center of rotation to be matched to the test article over a large range of adjustments. The large test table allows NTS to configure to test article as a package on the ground. Setup, calibration and pre-test is all done prior to lifting the package 12 feet in the air, eliminating physical hazards and making test article changes more efficient and expedient.

Will Roberts PE, Engineering Manager and his team have finished the primary installation and painting, the motor which will operate this machine is being installed now.  Contact the team in Huntsville to discuss this and other test capabilities.

Left to right on the floor: Will Roberts, Engineering Manager, Glenn Kalte, Chief Designer, Jim Birkholz, Senior Engineer-Drive Systems, Domenico Monastero , Senior Mechanical Engineer. On the Platform, Blake Rees – Test Engineer.

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!

Expanding Capabilities in Rocket City

EMI testing Huntsville ALIt has been a busy time at our Huntsville, Alabama test facility! We’re added a number of new chambers, enabling us to expand our test offerings for our defense and aerospace industry clients.

We have added two EMI chambers to our EMI department, bringing us to a total of six MIL-STD-461 compliance EMI Chambers. Additionally, a third new chamber is on the horizon to replace one of our older, smaller chambers. All of our new chambers have a low sill height, which eases the installation process for larger equipment under test (EUT).

The Huntsville EMI facility now has the necessary amplifiers and antennas to allow MIL-STD-461 radiated susceptibility testing up to 40- GHz at 200 V/m. Additionally, new equipment has been added that enables us to perform the common mode test required by MIL-STD-461F/G CS114 in the frequency range of 4kHz to 1 MHz for items that are intended to be installed on ships or submarines.

To learn more about these and other testing at NTS Huntsville, contact us today!

 

 

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!

What the FOD? Foreign Object Debris Testing at NTS

“As defined in AC 150/5210-24, Foreign Object Debris (FOD) Management, FOD is any object, live or not, located in an inappropriate location in the airport environment that has the capacity to injure airport or air carrier personnel and damage aircraft.” via https://www.faa.gov/airports/airport_safety/fod/

FOD can be a tool left behind, a piece of debris from a plane that recently departed, or a flock of geese. The presence of FOD is a significant concern for the safety of air travel. Airports, Airlines and manufacturers all play a part in the avoidance and minimization of FOD.

Testing systems and materials to determine their ability to withstand FOD is a key part of the development of safe airplanes. NTS conducts FOD testing at a number of our laboratories, including Tinton Falls, NJ.

The video below shows a 0.75 inch steel ball traveling at 187 mph hitting a 0.085 thick aluminum plate. The takeoff speed of the Airbus A340 and the Boeing 747 is 180 mph. The result is the 0.26 inch deep dent in the plate. The 747 outer skin, made out of aluminum alloy, is just 5 millimeters (0.2 inches) thick. Installed between it and the internal panels are soundproof and heat-resistant insulation materials. The wall is 19 centimeters (7.5 inches) thick.

Lightning Strikes!

Any electronic component is potentially susceptible to lightning damage. As sophisticated navigation and communication systems come to play a larger role in maintaining safe flight operations, lightning testing is an increasingly important part of quality control for both military contractors and avionics equipment manufacturers. Accurately replicating the effect a lightning strike will have on a device is the only way to measure its durability.

Increasing Vibration Capabilities in Boxborough, MA

The already extensive dynamics testing capabilities at our Boxborough, MA location are about to get even better!

We are eagerly awaiting the arrival of our new Unholtz Dickie T2000 – 3 – PB. This new shaker has a 3 inch stroke and a rating of 25,000 force pounds for sine vibration, 23,000 force pounds for random vibration, and 67,000 force pounds for shock. It has a F2000 Field Power Supply and Heat Exchanger with 2 bays, and series/parallel stators for high SRS shock.

This will be the eighth T2000 for NTS across the US, our other T2000 shakers are in Fullerton and Los Angeles, CA, Chicago and Rockford, IL, Camden, AR and in Plano, TX (above on installation day in 2016).

Contact us today to get your vibration testing scheduled! The schedule will fill up fast! Request a quote here, or contact the Boxborough team today!

Lightning Protection of Wind Turbines

lightning protection for wind turbinesOver the past decade, we’ve all watched the world’s energy markets shift towards cleaner, alternative sources. Technological advancements in renewable industries like wind, solar, and tidal, have enabled us to make these potential solutions a reality. As research and development continue to improve efficiency, and drive down cost, these solutions will become more and more prevalent.

We still face considerable obstacles. Wind turbines, in particular, take on one of the largest hurdles; weather. Their fixed location poses unique challenges for turbine and blade manufacturers, which are expected to increase the longevity and reliability of their products without compromising effectiveness, or substantially raising costs. Lightning strikes can cause significant damage to turbines. This damage is extremely expensive to repair, and can shut a turbine down completely.

Severe storms are generally comprised of one or more cumulonimbus clouds, which can be several kilometers in height. As these clouds develop, warm air rises towards the top of the cloud. As the air rises, it becomes cooler. At the dew point, excess water vapor condenses into water droplets and forms the cloud.

When the air has risen high enough, the temperature can drop to -40 degrees Celsius –  water vapor within the cloud will freeze. As ice crystals and hailstones form, and become heavier, they fall through the cloud. When additional water droplets freeze onto the hailstone, small splinters of ice chip off, many of which are positively charged (electrically). Together, these can deposit a net negative charge. Vertical winds carry these smaller splinters upwards into the cloud, while the hailstone falls until it reaches warmer air.

This process causes pockets of electrical charge to form within the cloud, which creates strong electric fields. These electric fields allow charge from the surface of the earth to be “pulled” upwards. in an effort to become charge neutral (typically through tall objects and structures). As these charges get closer together, the electric field in the air further intensifies until it reaches levels of ~30,000V/cm.

When the field intensity reaches these levels, air begins to break down, allowing charge (in the form of current) to flow through the air. Sharp objects significantly intensify the electric field, forming corona (also called St. Elmo’s Fire). Charge from the lightning cloud begins propagating towards the earth. At some point, charge from objects on the ground begins flowing upwards. When these two flows meet, a conductive channel is formed, and lightning occurs.

During a lightning strike, currents of up to (and even greater than) 200,000A travel between the cloud and the object where the lightning channel formed. Wind turbine blades have a sharp, aerodynamic profile – this not only allows them operate efficiently; it also makes them extremely susceptible to lightning strikes. Without suitable conduction paths to safely carry such high current, this transfer of energy can devastate a wind turbine blade.damaged wind turbine blade

Most wind turbine manufacturers strive to make blades and turbines that are more reliable, and can withstand natural phenomena such as lightning. These designs attempt to provide “preferred” current paths for the lightning current; conductive meshes over the exterior of the blades, lightning receptors (preferred lightning attachment locations), and large down conductors, help carry high currents safely to ground.

All of these precautions require highly-detailed planning that includes proper grounding of conductors, shielding of signal wires, wire routing, providing parallel current paths, etc. Despite the complexity of these designs, the benefits are significant; the effects of lightning are not entirely negated, but damage can be significantly reduced – instead of a total blade replacement, getting the turbine up and running again becomes a maintenance and repair exercise.

lightning damage repair progressionThe repair may be straightforward, but it’s still physically demanding. Most modern wind turbine blades are several dozen meters in length. The turbine tower itself can extend 50-100 meters above the ground. Maintenance workers must climb the tower, or be carried up to the blade via a crane. The repair generally involves removing the exterior coating, prepping the damaged area for repair, repairing the laminate, and reapplying the exterior coating.

The physics of nature make lightning almost unavoidable. Therefore, manufacturers must build an effective lightning protection design into the blade.

Most modern design approaches leverage a combination of numerical simulation and testing. Utilizing numerical simulation, electromagnetic models for wind turbine blades can be developed to analyze distributions between structural carbon, and surface protection layers. These models allow the determination of what is electromagnetically important, such as voltages or currents induced throughout the blade, including CFRP pultrusions, heater elements, surface protection layers, and down conductors. They capture critical design details such as material thicknesses, conductor routing, and receptor locations. Further evaluation exposes conductive materials and associated performance risks, such as arcing between blade elements, excessive current in structures, and induced transients into control systems.

After modeling is complete, one or several candidate protection designs is proposed, intending to conduct lightning current with lowest potential for damage or repair. In order for the model data to be considered high fidelity, it needs to be validated by replicating exactly the measurements taken during laboratory tests, and comparing them to the analytical data to determine correlation. This is typically done with high voltage strikes, high current physical damage testing and induced transient tests.

Lightning will always affect wind turbines. It’s complicated, and requires a well thought out design to reduce the severity of damage. If a good protection design is implemented, lightning damage can be reduced to a standard maintenance/repair operation, rather than a total loss.

Justin McKennon is a Senior Engineer and Manager of Simulation and Modeling at the NTS Pittsfield, MA location that specializes in lightning testing and protection services. Justin has a Bachelor’s and Master’s degree in Electrical Engineering from the University of Massachusetts, Dartmouth. He specializes in simulating and modeling the electromagnetic effects of lightning on wind turbine blades, electrical components, aircraft, and other structures.