This key metric is moving in the company's favor.GE Aerospace (GE 1.28%) stock trades up more than 60% year to date, and it's understandable if investors are starting to think it might be overvalued. However, the company's second-quarter earnings just revealed something that strengthens the investment thesis for long-term investors.Improving long-run profit potentialAerospace companies are typically not judged on near-term earnings, but rather on their potential for a long-term stream of recurring revenue f ...