Complex sentence: In 1989, "Morgenthau" was decommissioned to undergo a major mid-life renovation, the Fleet Rehabilitation and Modernization (FRAM) to upgrade berthing and living spaces, rejuvenate engineering systems, and modernize her major weapons and sensors.
Split into simpler sentences: In 1989, "Morgenthau" was decommissioned to undergo a major mid-life renovation under the Fleet Rehabilitation and Modernization (FRAM). The cutter's FRAM included updating berthing and living spaces, rejuvenating engineering systems, and updating/modernizing major weapons and sensors.