Principia doesn't take into account damaged engines

[FioraAeterna]

A testflight-damaged engine can have 50% performance loss -- which isn't necessarily the end of the mission! Perhaps, for example, you can do half the burn, getting into a highly elliptical departure orbit, then finishing the burn on the second go-around. Recovering from this kind of failure can be fun.

But unfortunately, Principia doesn't know that the engine is damaged, so it continues planning with the burn time as if it was not damaged, making this much more difficult to do.