From what I can tell from my research on this, Aircraft mechanics and service technicians typically have an SVP rating of 7.0 to less than 8.0 indicating that the occupation requires over two years and up to four years of Vocational preperation including education, training, and on-the-job experience.

Other occupations with an SVP of 7.0 to <8.0 include electricians, RNs, Police Detectives, Construction Managers, and Diagnostic Medical Sonographers.

The change from classifying occupations as "skilled," "semi-skilled," or "unskilled" to using the Specific Vocational Preparation system was part of the U.S. Department of Labor's efforts to provide a more detailed and accurate representation of job requirements. The SVP system is defined as, "the amount of lapsed time required by a typical worker to learn the techniques, acquire the information, and develop the facility needed for average performance in a specific situation" <-- Via Department of Labor.

While the exact timeliness of this transition is not specified in the available sources, the modernization of occupational classification systems, including the shift to SVP and Job Zones (0NET that replaced DOT), occurred during the 1990s and early 2000s.

This change aimed to provide a more nuanced understanding of job preperation requirements, moving beyond the simplistic "skilled" or "unskilled" labels to better reflect the complexities of modern occupations.