The aerospace industry has been reminded in recent years that structural integrity cannot be taken for granted. One of the most widely publicized events was the January 2024 in-flight structural failure involving an Alaska Airlines Boeing 737 MAX 9. Shortly after takeoff, a mid-cabin door plug separated from the aircraft, causing rapid decompression and substantial structural damage. Fortunately, the flight crew landed the aircraft safely and no fatalities occurred. Subsequent investigations by the U.S. National Transportation Safety Board (NTSB) concluded that the event resulted from multiple system failures, including missing retaining bolts and deficiencies in manufacturing quality assurance, training, documentation, and oversight. (NTSB)
Although the Alaska Airlines event was ultimately linked to assembly and quality-control issues, it highlights a broader truth in aerospace engineering: catastrophic failures are rarely the result of a single defect. Instead, they often involve a chain of missed opportunities for detection, verification, and corrective action. The aerospace industry has also faced ongoing scrutiny regarding structural integrity concerns in aircraft manufacturing, including investigations into fastener installation practices and long-term fatigue performance of airframe structures. (Reuters)
This is where Nondestructive Evaluation (NDE) plays a critical role. NDE methods are specifically designed to detect discontinuities, defects, and degradation before they become safety hazards. Techniques such as ultrasonic testing (UT), radiographic testing (RT), computed tomography (CT), eddy current testing (ET), and visual inspection can identify cracks, corrosion, manufacturing defects, disbonds, porosity, and other structural anomalies without damaging the component being examined.
In aerospace applications, NDE is used throughout the entire life cycle of a structure:
- During manufacturing to verify conformity and detect production defects.
- During maintenance to identify fatigue cracking, corrosion, and service-induced damage.
- During life-extension programs to evaluate aging aircraft.
- During failure investigations to determine root cause and prevent recurrence.
The importance of NDE becomes even more apparent when considering fatigue-related structural failures. Aerospace structures experience millions of load cycles during service. Small cracks can initiate at stress concentrations and grow over time until catastrophic failure occurs. Modern research continues to focus on crack-growth monitoring, digital image correlation, acoustic emission monitoring, and advanced structural health monitoring systems to detect damage before failure occurs. (arXiv)
For engineers, inspectors, and quality professionals, understanding NDE is therefore not simply a compliance requirement—it is a fundamental element of risk reduction and public safety.
The ATI Nondestructive Evaluation (NDE) Course provides students with the foundational knowledge needed to understand how inspection technologies are applied to prevent exactly these types of failures. The course introduces the principles, capabilities, limitations, and applications of major NDE methods used throughout industry and aerospace. Through this training, students gain an appreciation for how inspection planning, defect detection, probability of detection (POD), and inspection reliability contribute directly to structural integrity and safety.
Recent aerospace events serve as powerful reminders that quality assurance does not end at design or manufacturing. Effective NDE programs provide one of the most important safeguards against structural failures by ensuring that defects are identified and addressed before they can threaten aircraft safety. As aerospace structures continue to become lighter, more complex, and more highly optimized, the role of qualified NDE personnel and advanced inspection technologies will only become more important.