Which SSSn pertains to APU operation?

The correct set of standards, 49-10-01, directly pertains to APU operation as it is associated with the specific guidelines and maintenance protocols relevant to Auxiliary Power Units. This designation is necessary for Air Force personnel to reference when performing the operational checks, troubleshooting, and repair procedures for the APU. Each number in the sequence corresponds to a specific topic within Air Force technical orders, and 49-10-01 indicates a focus on power systems, which includes the APU.

Other options listed do not relate directly to APU operation. For instance, 12-30-25 and 12-15-01 typically deal with airframe systems or avionics rather than ground power sources like the APU, while 15-25-35 may relate to a different system entirely. Each of these code designations points to instructions or procedures outside the scope of APU operation, making 49-10-01 the appropriate choice for understanding the operational aspects of the Auxiliary Power Unit.