Complex sentence: The companies began a program for the improved G.222, named C-27J in 1996; this used a U.S. military type designation based on the G.222's C-27A U.S. designation.
Split into simpler sentences: The companies began a program for the improved G.222, named C-27J in 1996. This was a U.S. military type designation based on the G.222's C-27A U.S. designation.