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Machinist’s Mate Auxiliary

A United States Navy Machinist’s Mate Auxiliary inspects the diesel engine aboard a submarine.

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Machinist’s Mates Auxiliary (MMA) are systems specialists who operate and maintain non-nuclear mechanical systems aboard submarines. As an MMA, you are a vital element in the day-to-day operations. Your responsibilities as an MMA may include:

  • Manufacturing and storing oxygen
  • Removing carbon dioxide, carbon monoxide and hydrocarbons from breathable air
  • Maintaining and testing emergency diesel engines, watertight doors and hatches and mast and antenna hoists
  • Repairing and replacing on-board equipment such as valves, filters, pumps, compressors and hydraulic and pneumatic devices
  • Operating and repairing refrigeration systems and water desalination plants
  • Maintaining air conditioning systems and galley equipment
  • Keeping and analyzing records and reports for machinery

Work Environment

MMAs work primarily aboard submarines in the U.S. and abroad. You may also be assigned to shore stations for part of your Navy service, but most of your assignments will take place at sea. In this job, you can expect to be part of a team and perform work of a physical nature.

Training & Advancement

Upon completion of initial training at Recruit Training Command Great Lakes (known as Boot Camp), you’ll report for specialized training, including:

Basic Enlisted Submarine School (9 weeks) in Groton, CT, for training on basic submarine systems.

Machinist’s Mate "A" School (9 weeks) in Groton, CT, for training on mechanical theory, safety precautions and programs, piping systems and equipment, mechanical systems and equipment, tools and instruments, the Maintenance Material Management System (3M), technical documentation and basic watch standing procedures.

Machinist’s Mate "C" School (7 weeks) in Groton, CT, King’s Bay, GA, or Mangor, WA, for specialized training on technical knowledge and skills necessary for auxiliary systems operators.

After you complete your training, you may be assigned to a submarine or a naval repair station in the United States or overseas. While the majority of your career will take place at sea, you may also receive shore assignments such as recruiting duty or serving as an instructor at “A” or “C” Schools.

Promotion opportunities are regularly available but competitive and based on performance.

Advanced Training

Advanced training as a Machinist's Mate Auxiliary may also be available during later stages of your career. For those with further leadership aspirations and a college degree, Officer roles may be available, providing opportunities to lead and train others.

Post-Service Opportunities

Specialized training received and work experience gained in the course of service can lead to valuable credentialing and occupational opportunities in related fields in the civilian world, such as power plant operation, industrial machinery and more.

Education Opportunities

Beyond offering access to professional credentials and certifications, Navy technical and operational training as a Machinist’s Mate Auxiliary can translate to credit hours toward a bachelor’s or associate degree through the American Council on Education.

You may also continue your education through undergraduate degree opportunities like the Navy College Program and Tuition Assistance and the Post-9/11 GI Bill.

Qualifications & Requirements

A high-school diploma or equivalent is required to become an Enlisted Sailor and a Machinist’s Mate Auxiliary. You must also be a U.S. citizen eligible for security clearance.

MMA applicants must be willing to serve aboard a submarine. You should possess excellent math skills, good speaking ability, the ability to keep accurate records and perform detailed work, and an aptitude for working with tools, equipment and machines.

Important personal traits for MMA applicants include the ability to get along with others and work well as part of a team. Good manual dexterity is required.

General qualifications may vary depending upon whether you’re currently serving, whether you’ve served before or whether you’ve never served before.

Part-Time Opportunities

Serving part-time as a Navy Reserve Sailor, your duties will be carried out during your scheduled drilling and training periods. During monthly drilling, Machinist’s Mates Auxiliary in the Navy Reserve typically work at a location close to their homes.

For annual training, you may serve anywhere in the world, including locations in the U.S., at bases overseas, or in areas where humanitarian needs are great.

Take a moment to learn more about the general roles and responsibilities of Navy Reserve Sailors.

Most of what you do in the Navy Reserve is considered training. The basic Navy Reserve commitment involves training a minimum of one weekend a month (referred to as drilling) and two weeks a year (referred to as Annual Training) – or the equivalent of that.

Machinist’s Mates Auxiliary in the Navy Reserve serve in an Enlisted role. Before receiving the ongoing professional training that comes with the job, initial training requirements must be met.

For current or former military Enlisted servicemembers, prior experience satisfies the initial Recruit Training requirement, so you will not need to go through Boot Camp again.

For those without prior military experience, you will need to meet the initial Recruit Training requirement by attending Boot Camp in Great Lakes, IL. This training course will prepare you for service in the Navy Reserve and count as your first Annual Training.