Raytheon Technologies Corp., one of the world’s largest aerospace and defense companies, is considering a $1 billion sale of one of its services units, according to people familiar with the matter.The company — parent of Collins Aerospace, Cedar Rapids’ largest employer — is working with an adviser to look at strategic options for the unit, including a sale, said the people, who asked not to be identified because they weren’t authorized to speak publicly.The unit, which provides training for the repair and maintenance of equipment, vehicles and machinery, is likely to interest private equity firms, the people said.A final decision on pursuing a sale hasn’t been made and Raytheon could elect to keep the business, the people said.A spokesperson for Raytheon, based in Waltham, Mass., declined to comment.