Complex sentence: It was not until the spring of 1944 that the engine was routinely lasting 50 hours and could enter full production, going on to power the majority of the Luftwaffe's jet designs.
Split into simpler sentences: It was not until the spring of 1944 that the engine was routinely lasting 50 hours and could enter full production. It nevertheless went on to power the majority of the Luftwaffe's jet designs.