[helicon]

Apollo 12 was struck by lightening shortly after launch. I wondered initially if this was the reason for the "extra long burn of the ullage motors".

But according to the Apollo 12 wikipedia page: "a small error in the state vector in the Saturn's guidance system caused the S-IVB to fly past the Moon at too high an altitude to achieve Earth escape velocity".

http://en.wikipedia.org/wiki/Apollo_12