3 Strategies for the NDT of Aerospace Composites

Composite materials have become increasingly important components for airplanes and spacecraft. The failure of a single composite component, or the airframe itself, can cause flight failure. This risks lives and, in this high-dollar industry, up to hundreds of millions of dollars. In addition, aircraft inspections are required by law, imposing further financial penalties on aircraft owners and manufacturers who neglect them. Yet composite materials are difficult to inspect for defects or wear. So, aerospace companies rely on nondestructive testing (NDT) solutions, like advanced ultrasonic techniques, to ensure safe flights and profitable operations. Following established best practices predicts success in the NDT of aerospace composites. 

NDT Capabilities for Aerospace Composites

Many different NDT strategies can be used to inspect aerospace composites, including visual inspection, ultrasonic testing, thermography and more. Of these, phased array ultrasonic testing is often preferred for its speed, portability, capability, reliability, and cost. 

The tolerances of composite materials used in airframes, such as carbon fiber reinforced plastics, have been mapped thoroughly. Defects or damage to composite structures including increased porosity, the presence of voids or foreign materials, variation in the density of the carbon fibers themselves, and delamination can cause materials failure during flight. 

These defects can be detected using a combination of phased array ultrasonic testing instrumentation with an agile scanner and probes that don’t require an immersion tank. With this approach, the component or area being testing can be safely flagged for repair or removal from service. 

In order to successfully detect damage and defects in aerospace composites using NDT methods, companies should follow a simple set of strategies as standard practice. 

Aerospace NDT: Strategies for Success

Aerospace companies must possess adequate equipment, knowledge, and diligence to successfully implement an NDT testing regime for the composite materials essential to their aircraft. 

NDT Equipment for Aerospace Composites

Aerospace operators and manufacturers must invest in quality equipment to sufficiently scan their composite components. Separate pieces of equipment are needed for phased array ultrasonic scanning. In addition to the instruments themselves, agile scanners with location and orientation tracking capabilities, as well as flexible wedge and immersion probes are also necessary for efficient operations. Advanced software capabilities embedded in the instrument guide technicians through the process, help identify defects, and prepare documentation for internal and external review. Given the size of airframes, portable equipment without the need for an immersion tank is greatly preferred. 

NDT Knowledge for Aerospace Composites

It is imperative for technicians performing NDT inspections on aircraft to be appropriately trained and certified. As technology and materials develop, technicians should also be periodically recertified. Companies should allow technicians time to pursue training opportunities relevant to ultrasonic testing of aircraft, as well as seek out qualified technicians from elsewhere. For example, NDT certification is prescribed by the American Society for Nondestructive Testing, and competent trainers can be found at universities, third-party laboratories, and NDT equipment manufacturers. 

Diligence in NDT Testing of Aerospace Composites

Companies must exercise diligence in several ways to successfully implement an NDT testing program. Directly, technicians must meticulously perform their testing duties—and be incentivized to do so. Managers should schedule adequate time for recurring, routine testing, as well as training, while continuously ensuring that technicians and equipment are both performing up to expectations. Finally, recordkeeping must be kept up-to-date as well, in order to provide research data for the company in addition to proof of inspection for the Federal Aviation Administration and other regulatory bodies. While advanced software capabilities on modern NDT instruments can record and prepare data, it is up to company officials to carefully organize, store, and preserve that data in order for it to maintain value. 

With the right equipment, the right knowledge, and a diligent approach to the task, aerospace companies have all they need to safely and successfully certify their aircraft for flight. 

At Zetec, we have the equipment and the knowledge your company needs to safely test the composite materials used in your aircraft. To learn more,  contact us today!