Machinist’s Mate, Auxiliary (MM-AUX)

Navy Enlisted Rating (Job) Description

USS City of Corpus Christi
Steve Kaufman / Getty Images

The MM-AUX is a Machinist Mate (MM), assigned aboard a Navy submarine, who specializes in maintenance and repair of auxiliary equipment. MM-AUX are specialists that work to maintain and operate the different submarine mechanical systems, and non-nuclear related operations systems in air, refrigeration, hydraulic, atmosphere control, diesel and plumbing systems. You cannot get a guarantee for this rating. You can volunteer to become a Submarine Machinist Mate, and you are assigned to either MM-AUX or MM-WEP (Machinist Mate for submarine weapons) during the training pipeline. There are also nuclear-trained Machinist Mates aboard Navy submarines.

Typical duties include:

  • manufacturing and storing oxygen;
  • removing airborne waste products such as carbon dioxide, carbon monoxide, and hydrocarbons;
  • cleaning, adjusting, testing and performing preventive maintenance on submarine emergency diesel engines, mast and antenna hoists, hatches and watertight doors;
  • repairing or replacing valves, filters, pumps, compressors and hydraulic or pneumatic control devices; operating, troubleshooting and repairing ship's refrigeration systems;
  • testing equipment using voltmeters, ammeters, meggers, and ohmmeters;
  • testing and replacing portable cable, self-contained relays, lamps, and fuses; locating and identifying components and assemblies of electronic equipment;
  • using and caring for common hand tools, special tools, and soldering equipment;
  • tracing mechanical/electrical circuits on schematics and drawings.

Working Environment

Machinist's Mates (Submarines) work within, and external to, the hull of a submarine in engine rooms or shops that are sometimes hot, noisy and dirty. Their work is sometimes physical, and they must be able to work closely with others as well as alone with limited supervision.

A-School (Job School) Information

  • Groton, CT -- 4 weeks (Basic Enlisted Submarine School)
  • Groton, CT --4 weeks (Sub MM A School)

Note: Following MM A School, students go on to either the Auxiliary Pipeline or follow-on Weapons courses.

ASVAB Score Requirement: VE+AR+MK+MC=210

Security Clearance Requirement: Secret

Other Requirements

  • Must be U.S. Citizen
  • Most have normal color perception
  • Must have normal hearing.
  • Must volunteer for submarine duty
  • Must have no record of conviction by civil court for any offense other than minor traffic.
  • Moral turpitude offenses are generally disqualifying.
  • No history of drug abuse.
  • This job (like all submarine jobs) is closed to women

Sub-Specialties Available for This Rating: Navy Enlisted Classification Codes for MM

Current Manning Levels for This Rating: CREO Listing

Note: Advancement ( promotion ) opportunity and career progression are directly linked to a rating's manning level (i.e., personnel in undermanned ratings have greater promotion opportunity than those in overmanned ratings).

Sea/Shore Rotation for This Rating

  • First Sea Tour: 54 months
  • First Shore Tour: 36 months
  • Second Sea Tour: 42 months
  • Second Shore Tour: 36 months
  • Third Sea Tour: 42 months
  • Third Shore Tour: 36 months
  • Fourth Sea Tour: 36 months
  • Forth Shore Tour: 36 months

Note: Sea tours and shore tours for sailors that have completed four sea tours will be 36 months at sea followed by 36 months ashore until retirement.

Much of the above information courtesy of the Navy Personnel Command