Journal of Aviation/Aerospace Education & Research





Key words

safety management systems, Part 21, Part 145, Airworthiness Directives, design and manufacturing, aviation, safety


The European Union Aviation Safety Agency (EASA) continues to promulgate Safety Management Systems (SMS) across aviation organizations when it recently issued SMS requirements for EASA certificated Part 145 maintenance, repair and overhaul (MRO) organizations and Part 21 Design & Manufacturing (D&M) organizations. Currently, the Federal Aviation Administration (FAA) has no such rule in place for these U.S.-based organizations, which may challenge those doing business in countries where EASA policies apply. Given that a majority of the United States’ D&M and MRO population is made up of smaller organizations, it is likely a U.S. SMS regulation will require justification of the associated costs and benefits. This study explored the potential benefits SMS may provide these organizations by exploring the overall scope and nature of safety controls implemented through Airworthiness Directives (AD), which may help safety practitioners better understand how SMS in D&M organizations may reduce the number of AD related corrective actions. Researchers analyzed a sample of 189 ADs issued over a ten year period and found that approximately 55% of the sampled ADs were the result of a new risk control and approximately 45% were the result of a revised risk control. In these cases, the risk controls were not sufficient, and the AD action was necessary to ensure an acceptable level of safety. More effective risk controls have the potential to significantly reduce the number of ADs the industry must address. Every AD involves unplanned costs, often at multiple levels, and other variables that must be managed and implemented as part of the aircraft maintenance and manufacturing process. SMS may further improve the industry’s safety performance by reducing the number of corrective actions and their associated costs.



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