V. 1. 5. 1
Engine Component designs are not disappearing when obsoleted but other components are still able to. Ship design window, No error text, weirdly I was able to obsolete 1 of the two engines but after some time designing a ship, making prototype comps it just wont disappear as obsolete comp. it was a conventional start, 49 years into the game, intermittent after some times 3 engines were now unable to be obsoleted.