Boeing Co., stinging from the recent loss of a major military satellite contract, is expected to announce that it plans to cut the jobs of about 750 engineers and technicians, most of them in Southern California. The job cuts mark one of the largest for the region's aerospace industry in the last few years and come on the heels of Boeing's losing out on what is expected to be one of the last big space programs for at least a decade. The contract, potentially worth more than $3.5 billion to build a new generation of GPS satellites, was awarded to rival Lockheed Martin Corp. The global positioning satellites are intended partly to make the now-ubiquitous GPS navigation equipment more accurate and powerful. Chicago-based Boeing, the largest private employer in the region with 31,000 workers, would have made the satellites at its sprawling facility in El Segundo where it has a workforce of about 5,000. The bulk of the job cuts are expected in the South Bay area, which in recent years enjoyed a resurgence of aerospace jobs amid a surge in defense spending.