What is the 91 series?

• A. Electrical systems maintenance
• B. Mechanical maintenance and repair
• C. Supply management
• D. Engineering and construction

Answer: (B)

The 91 series is the Army’s maintenance career field focused on mechanical maintenance and repair of equipment and vehicles. This designation covers diagnosing mechanical faults, repairing engines, transmissions, drivetrains, suspensions, and other mechanical systems, as well as performing preventive maintenance and component replacement to keep gear operational. It’s the pathway you’d expect for technicians who work on the moving parts of vehicles and mechanical hardware, rather than on electrical/electronic systems, supply management, or engineering and construction. So the best fit is mechanical maintenance and repair.