Advancements Lead to Better Lightning Tests for Aircraft

August 2006

Today’s aircraft incorporate more—and more complicated— electrical and electronic systems. As a result, the requirements for lightning susceptibility testing of aircraft avionic systems have grown accordingly.

Advancements in lightning research have helped us better understand the complex nature of lightning and its effects on avionics. Through ongoing research and development, the test methods and requirements have evolved into today’s stringent lightning tests, demonstrated in industry specifications such as Section 22 of RTCA DO-160E.

Recognizing the need to remain at the forefront of lightning test services, Elite has invested heavily in lightning equipment and test technology.

A Lightning Primer
The probability of a lightning strike to an aircraft depends on local climate, type of aircraft and other factors. In climates where lightning occurs commonly, the estimated probability of a lightning strike to a commercial aircraft is approximately one in every 1000 hours of flight.

In a lightning strike, the aircraft becomes part of the conductive path between the electrically charged cloud and the oppositely charged ground—or, in some cases, the oppositely charged neighboring cloud. Lightning attaches to a particular portion of the plane and travels as an electrical current along the aircraft structure and fuselage. It exits the plane at a wingtip or another rear projection of the plane as it travels to a lower voltage potential.

A direct lightning strike has a peak current amplitude of approximately 200,000 amperes. The heating effects and rate of rise from these currents cause failures ranging from damage to antennas, radios and instruments to burnout of components such as Electromagnetic Interference (EMI) filter capacitors and relay suppression diodes.

The “indirect effects” from lightning strikes refer to the current and voltage transients that are picked up on the aircraft wiring harnesses as a consequence of the direct strike.

Electrical currents from a direct strike produce electromagnetic radiation which couples to the harness. Lightning currents also conduct through equipment leads and grounds attached to aircraft structure grounds.

Indirect voltages and currents can be as high as 4,000 volts and up to 5,000 or more amperes. They can damage electrical/electronic components. Their repetition rate and fast rise times can also produce data errors and erroneous commands on digital systems and consequently compromise the continued safe operation of the aircraft.

The indirect environment is commonly described with five individual waveforms which represent the potential composite effects of the induced currents on cabling and equipment interfaces. These waveforms are defined by rise time, decay time, peak amplitudes which are then applied to double exponential (short and long duration), derivative double exponential and damped oscillatory wave shapes.

The amplitudes of the wave shapes are stated in terms of the open circuit voltages and short circuit current. Five standard amplitude levels are identified, though special wave shapes and amplitudes are required when applicable to a particular aircraft situation.

Single pulse (Single Stroke) transients are applied to individual pins to evaluate the damage susceptibility of the test. In addition, a series of pulses (Multiple Stroke and Multiple Burst) are coupled onto the cable harnesses to evaluate the operational susceptibility of the system.

We put Lightning to the Test
For years, Elite has maintained a highly capable lightning test ability to complement its military, aviation and telecommunication RF testing. Our most demanding levels have included pulses on surge arrestors and other lightning protection equipment at short-circuit current levels up to 20,000 amps and open-circuit voltages of 10,000 volts.

In May, 2005, we began to develop a new generation of lightning test equipment and protocols. The effort was led by Thomas Klouda, Assistant Director of Engineering and chief lightning and electrical surge expert.

Elite now has full level-five capability for the RTCA DO-160E lightning surge testing on pins or cable bundles. We can also generate damped oscillatory pulses at 1MHz and 10MHz in the multiple burst format at the level 5 amplitudes. And our newly developed pulses are tailored to special OEM requirements, such as the Joint Strike Fighter and F-22 Raptor.

Elite will present our enhanced lightning test capabilities on August 17 at the Portland 2006 EMC Symposium New Product Showcase. For more details on test levels and achievable current and voltage limits, as well as a complete listing of our capabilities, please contact an Elite sales engineer.

Elite Provides Research into Correlation Issues between ALSE and MTRC

August 2006

Automotive, military and aerospace specifications allow for the use of either an Absorber Lined Shielded Enclosure (ALSE) or a Mode Tuned Reverberation Chamber (MTRC) to perform radiated RF immunity testing on electronic modules. While both methods are industry accepted, they can provide significantly different test results in practice.

A team of Elite engineers, headed by EMC Laboratory Manager Craig Fanning, evaluated the correlation issues between these two methods in relation to automotive industry standards. The study results support the use of a reference ground plane in an MTRC without adversely affecting test results. The engineering team also addressed possible causes for the lack of correlation and the use of innovative equations, which achieve correlated results between the two test methods.

The results of this study are being evaluated by the SAE and ISO committees charged with developing standards for ALSE and MTRC testing. A technical paper covering the study will be presented by Craig Fanning at the 2006 EMC Symposium in Portland, Oregon.

Elite Achieves Canada Certification

August 2006

In February, Elite received its designation as an Industry Canada Certification Body (CB) for radio frequency transmitters. This new recognition adds to Elite’s present resume of certification services. They include Telecommunication Certification Body (TCB) for FCC Certification and CAB/Notified Body for European Union CE Markings. Elite is also in the process of establishing other international recognitions and certification credentials to provide clients with seamless and convenient access to global markets. These services will be available directly through Elite as well as established international partners.

Accredited Calibration Services via Elite Partner: Standards and Calibrations

August 2006

As an accredited laboratory with more than 2,500 separate units of test instrumentation and equipment, Elite faces a formidable task maintaining all its equipment in calibrated and ready-for-service condition. To meet the challenge, Elite has relied on Standards and Calibrations of Des Plaines, Illinois, to augment our in-house calibration effort with outsourced calibration expertise.

Standards and Calibrations is an A2LA accredited full-service calibration laboratory providing services on a wide range of instruments such as voltage meters, temperature measurement instruments and dimensional gauges. Their capabilities include frequency and time calibrations required for calibrating RF test equipment such as Rohde & Schwarz receivers and Agilent RF power meters, spectrum analyzers, and signal generators.

Elite has partnered with Standards and Calibrations in order to offer accredited calibration services to Elite clients. If your company has development or compliance test equipment that requires calibration, Elite can offer a convenient and cost effective solution through its association with Standards and Calibrations. Contact an Elite sales engineer for details today.

John Lindberg Receives Environmental Award

August 2006

Elite’s Environmental Laboratory Manager, John Lindberg, received the David S. Steinberg Award at the Institute of Environmental Science and Technology Symposium in May, 2006.

The award is given for outstanding achievement in improving the reliability of electronic equipment that operates in severe environmental conditions—including vibration, shock, acoustic and various thermal extremes. Mr. Lindberg received the award for his contribution in identifying problems and developing solutions in many commercial products and in military equipment.

Elite Celebrates 50 Years of Testing Innovation

May 2004 - Company’s history is marked by growth

In many ways, Elite Electronic Engineering began aboard a United States Air Force bomber. Flying out of Wright Patterson Air Force Base in Dayton, Ohio, the bomber was equipped for the first time with a new, aerial camera. That camera could produce consistent photographic intelligence by adjusting automatically to the plane’s altitude and speed.

That first flight took place in the 1950s—and it didn’t go well. As soon as the camera was turned on and began to function, its electronics began to interfere with the bomber’s autopilot programming. The plane would gain altitude, then readjust to its original setting, and then gain altitude again. In no time, the camera was turned off and the bomber was back on the ground. An urgent call was placed to the manufacturer’s engineer in Chicago, James C. Klouda—Elite’s founder.

With a little sleuthing—and a little shielding—Klouda made the necessary adjustments to the firm’s prototype model and air-shipped it to the Air Force base for testing the next day. There was no interference the next day and the in-flight test went off without a hitch.

Elite’s founder went to work expanding his knowledge—and understanding the application—of EMC testing technology. About five years later, James Klouda approached the military about creating an engineering firm with a testing focus on EMC. He was encouraged to do so.

“Fifty years doesn’t seem that long ago. But we’ve seen a lot of change since then,” Klouda said. He is currently Elite’s President. “Technology has advanced so far and so fast-and we’ve made it a company-wide goal to always keep pace.”

While the company has grown exponentially in both customers served and services offered, the original values that Elite was founded on still hold true today. They include:

• Constant investment in new technology
• Cost-efficient and time-efficient testing
• Comprehensive dedication to the customer

Those principles have helped Elite become a leader in the industry—and have helped the company grow consistently during the past half century. In 1954, Elite had two employees and operated out of a 2,500 square foot storefront in south Chicago. By 1973, the company had 20 employees and occupied 22,000 square feet. Today, with 50 employees, and more than 45,000 square feet, Elite can offer unmatched expertise and equipment.

“We know that to stay on top we have to offer the best equipment and a fair price. But there’s more to it than that,” Klouda said. “We also have to offer experienced and knowledgeable people. Many of our people have been with us for decades.”

The company is substantially larger, the technology is significantly more advanced and the customer base is greatly diversified, but one thing hasn’t changed in 50 years: Elite is dedicated to complete customer satisfaction.

“I think back to that Air Force bomber every now and then,” Klouda concluded. “It turns out that camera wasn't the only good idea to get off the ground that day.”

Elite Plays It Cool with Liquid Nitrogen

As part of an initiative to expand and enhance its Environmental Stress Lab, Elite has recently installed a bulk liquid nitrogen (LN₂) system. The new LN₂ system utilizes a 6,000-gallon vacuum-insulated storage vessel, special vacuum jacketed piping to deliver the liquid to various chambers and cryogenic controls for its test chambers.

With LN₂, Elite can achieve extremely fast thermal ramp rates for its HALT/HASS testing. In addition, LN₂ is used for more efficient thermal shock testing, very low temperature cycling tests and to eliminate moisture for extremely low-humidity tests.

Elite chose vacuum-jacketed piping (VJP) over conventionally insulated copper piping because of its superior insulation performance. With VJP, the liquid retains its state longer, eliminating frost accumulation and sweating on the pipe exterior. This initial investment in VJP will reduce the higher operating costs associated with liquid loss due to evaporation.

“Our customers tell us that it’s not only important we develop new capabilities, but to also find ways to reduce overall costs,” says Steve Laya, Elite’s Sales and Marketing Manager. “This investment in bulk LN2 accomplishes both those goals.”

Several New Initiatives Keep Elite Ahead of the Field.

August, 2003 - Recent additions from software to personnel—at Elite demonstrate the firm’s commitment to innovation and constant improvement.

“We’re not about status quo. We constantly look for ways to deliver greater value-added services to our clients,” said Steve Laya, Elite’s Sales & Marketing Manager. “Through our new service enhancements, Elite can now better assist customers reduce development time, cut compliance test costs, and get products to the marketplace quicker.”

EMI Software Simulation and Circuit Modeling Services
Elite now offers leading-edge EMI computer simulation services to model electromagnetic emissions from printed circuit boards (PCB). Utilized early in the development cycle, these services provide advantages that include:

Design insight and increased attention on circuit elements that may cause non-compliant testing.

Reduced manufacturing costs. Because the PCB is optimized as a “virtual board,” fabricating many PCB iterations becomes unnecessary.

Virtual design iterations are generated quickly thereby reducing development time.

Software output and design modifications performed in a virtual environment easily facilitate “what-if” analysis.

Reduced costs for compliance testing and retesting.

Elite utilizes Omega PLUS Signal Integrity and EMI simulation software from Quantic EMC Inc. Omega PLUS provides all the tools to evaluate SI/EMI performance, crosstalk, ringing, overshoot, undershoot, settling time, and noise margin violations. Near-field radiated emissions are predicted from tracks, vias, and pins, even if the board is encapsulated in copper planes.

Elite also offers the Flomerics FLO/EMC system-level modeling software. This powerful tool analyzes emissions from enclosures and cabinets, including the effects of cables, seams and apertures. Applications include shielding effectiveness, far-field emissions prediction, and RF coupling between aircraft wiring harnesses and airframe.

HALT/HASS Testing Added to Environmental Stress Lab
HALT (Highly Accelerated Life Testing) involves applying combined six-axis vibration and temperature extremes. HALT overstress testing systematically produces test item failures to rapidly identify mechanical, electrical, design and functional vulnerabilities that demonstrate design weaknesses.

HASS (Highly Accelerated Stress Screening) is an overstress test that identifies defective products before shipment. HALT and HASS have become essential industry accepted elements in the product design, validation, and manufacturing cycle. By accelerating the discovery of design flaws before a product is in full production, manufacturers save significant time and costs associated with test and validation, warranty replacement costs, and product liability litigation.

HIRF Testing at 2,000 V/m to 3,000 V/m
A recent acquisition of specialized equipment means Elite can now generate extremely high intensity radiated fields (HIRF). This new capability serves Elite ’s commercial aviation and military clients who manufacture aircraft avionics, engine controls and electrical power systems.

Many such systems must now comply with rigorous DO-160D, military and OEM requirement for immunity to high intensity RF. HIRF testing ensures that critical aircraft systems operate safely when exposed to radar, radio and television broadcast stations, and/or satellite and other communication transmitters.

Elite’s new powerful amplifiers, high-gain antennas, and custom test automation software generate pulsed RF fields in excess of 3,000V/m. In addition to the pulsed RF, other Elite equipment delivers CW and modulated fields up to 600V/m at 1 meter test distance.

Elite clients can now comply with typical test profiles as well as the most severe EMC requirements through one test laboratory, which means greater convenience and project cost savings. The acquisition of this equipment demonstrates Elite’s commitment to remain a leader in testing for commercial aviation and military electronics.

John Lindberg joins Elite’s Environmental Stress Test Laboratory.

DOWNERS GROVE, IL July 2003 - Elite Electronic Engineering is proud to announce the addition of John Lindberg to the environmental stress test laboratory staff. John has worked in environmental stress testing for or the past 19 years providing expertise in mechanical vibration, shock, and simulated environments.

In addition to his responsibilities at Elite’s environmental lab, Lindberg will also head Elite’s new HALT/HASS accelerated testing services. A new Thermotron HALT/HASS chamber is scheduled to be on-line at Elite by the end of July 2003. Following installation of the HALT chamber will be a new 19,000 force-lb vibration table. The new vibration table and controller will provide enhanced field data replication capabilities and enable the generation of vibration profiles associated with actual product environments.

“The addition of John Lindberg signals a major commitment by Elite to expand its environmental stress test laboratory”, said James Klouda, Elite’s President and founder. “We’re very excited to have an engineer with John’s credentials, expertise, and reputation of excellence available to assist our clients with their test and reliability needs”.

Elite has a full environmental stress test laboratory including vibration, mechanical shock, temperature/humidity/altitude, corrosion, and many other types of climatic and dynamics testing.

Elite Electronic Engineering was founded in 1954 as an independent EMC test laboratory and engineering consulting firm. It is a privately held company providing testing, as well as EMC regulatory and design engineering services. The company has its main laboratory in Downers Grove, Illinois and an EMC test facility in Cocoa Beach, Florida. Elite serves the automotive, military, aerospace, industrial, commercial, and telecommunication industries.

Contact Steve Laya at Elite Electronic Engineering for additional information on this release. (1-800-ELITE-11)

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