How many sub-categories does a JAR 66 CAT-A certifying staff license have?

The correct answer highlights the specific categories defined in the JAR 66 structure for certifying staff licenses. A CAT-A certifying staff license pertains to the maintenance of aircraft and is the foundational level of certification. The categories under JAR 66 further classify the areas of aircraft maintenance into distinct groups based on the complexity and type of aircraft systems.

In this framework, the categories are differentiated as follows: Cat A refers to aircraft maintenance where the staff is qualified to perform maintenance on airframes and systems. B1 and B2 categories specialize further, with B1 focusing on mechanical systems and B2 on avionic systems. Category C relates to the authorization for the maintenance of large aircraft.

Therefore, understanding this classification represents the correct answer. The other options presented do not conform to the standard JAR 66 classifications as they either introduce incorrect category labels or do not delineate the structure accurately. This understanding reinforces the hierarchy and specialization present in aircraft maintenance licensing.