Percival next commanded the U.S. schooner on an 1830–1831 cruise against the troublesome West Indian pirates. While on leave in 1832, the department notified him of his promotion to Master Commandant effective in March 1831. After, in 1834–1835, he had the U.S. sloop-of-war on the Brazil station. In 1836, once again, he took over as executive officer in Boston. While assigned this duty, Percival displayed his concern for the welfare of the common sailor. A group of seamen transferring from the Brooklyn yard to Boston were injured, four of them seriously, when their train derailed along the way. The four received a total settlement of $12,862. Percival volunteered to administer a trust set up in behalf of the men. He did so over several years with prudence and faithfulness, paying out every cent to the beneficiaries or their survivors. The extensive and detailed record of Percival's careful and honest handling of the matter can be found in his papers at the Massachusetts Historical Society. (This relatively insignificant episode warrants this brief mention, because a careless writer, relying on insufficient research, wrongly charged that Percival absconded with the funds. From time to time, the misrepresentation is repeated.)