Hydrogen embrittlement (HE) poses a critical safety risk in the aviation industry, causing unexpected failures in high-strength metals and alloys used in essential components. This study focuses on detailed analyses of multiple aviation incidents and accidents where HE played a significant role, particularly concerning failures in helicopter drive systems and fixed-wing aircraft crankshaft bolts. Investigations revealed that these failures were primarily caused by hydrogen introduced during manufacturing processes, such as electroplating and surface treatments, which were insufficiently mitigated by post-processing techniques like dehydrogenation. These incidents led to Airworthiness Directives (ADs), which mandated corrective actions to prevent similar occurrences, such as improved manufacturing protocols and enhanced material testing. By presenting concrete evidence from metallurgical analyses and documented aviation failures, this paper highlights the critical need for robust manufacturing controls, stringent post-treatment procedures, and continuous monitoring to address hydrogen embrittlement risks effectively and enhance aviation safety.

Hydrogen embrittlement (HE) poses a significant risk in the aviation industry, leading to unexpected failures in high-strength metals and alloys used in critical components. This paper investigates multiple aviation incidents where hydrogen embrittlement contributed, notably in helicopter drive systems and fixed-wing aircraft crankshaft bolts. The failures were attributed mainly to hydrogen introduced during manufacturing processes, particularly electroplating and surface treatments, which left residual hydrogen despite dehydrogenation procedures. These incidents led to the issuance of Airworthiness Directives (ADs), which mandated stricter manufacturing controls and post-processing treatments, such as baking, to eliminate residual hydrogen and prevent future embrittlement. While the paper briefly covers traditional mitigation strategies like cathodic protection and surface coatings, its primary focus is on the need for improved quality control in manufacturing processes to reduce hydrogen-related failures, thereby enhancing the safety and reliability of aviation systems.