"Also, during the holidays there was a flight from Philadelphia to London that did a u-turn about 3+ hours into the flight, and returned to the Philadelphia airport. I don't recall if there was any follow-up info. regarding why they returned."
There was a follow-up...it returned to Philly, stayed for a whole 3 mins and then took off for London again.
Air ambulance crashes in Wyoming.
http://www.signonsandiego.com/news/nation/20050112-1332-wst-airambulancecrash.html