The last combatant ship commissioned at the Boston Naval Shipyard, Thomas C. Hart conducted sea trials off the east coast before being homeported in Norfolk, Va.

Following shakedown at Guantanamo Bay, Cuba, she returned to the Norfolk Naval Shipyard on 1 February 1974, where she underwent a major structural conversion, altering her after superstructure to accommodate the new Light Airborne Multi-purpose System (LAMPS) facilities.

Deploying to the Caribbean, Thomas C. Hart conducted weapons systems tests and antisubmarine exercises and, upon completion of these duties, called at Port-au-Prince, Haiti, before returning to Guantanamo Bay for further training.

This deployment, which lasted from 16 June to 22 December, consisted primarily of operations with USS John F. Kennedy and other escorts while making a number of port visits in company with Pharris.

Thomas C. Hart spent the first six months of 1976 engaging in two major fleet exercises in preparation for her four and one-half-month, unsupported participation in Unitas XVII later in the year.

The second exercise, "Solid Shield," occurred during the period 13 to 18 May and involved operations off the coast of the Carolinas in support of a full amphibious landing on Onslow Beach.