IIRC according to Feynman's memoirs the O-rings were the leading candidate already in his first meeting with NASA engineers, and in his first days in DC General

IIRC according to Feynman's memoirs the O-rings were the leading candidate already in his first meeting with NASA engineers, and in his first days in DC General Kutyna made the link to cold-weather brittleness. It did not take them months to have a plausible idea. They spent months looking into lots of things anyway.