During World War II, combat aircraft with significant accomplishments were sometimes pulled from front line service and flown back to the United States to conduct War Bond Tours. Hell's Angels, a B-17F-25-BO (S/N 41-24577) of the 358th Bomb Squadron, 303rd Bomb Group, was one of the first aircraft to participate in a War Bond Tour.
It was common for people building aircraft to "sign" aircraft at significant spots in the production run (i.e. 5,000th aircraft built). The members of the 358th Bomb Squadron got the idea to sign the Hell's Angels before it left for the States. The idea caught on and other squadrons signed their aircraft before sending them back to the United States. In addition to being the first 8th Air Force B-17 to complete 25 combat missions, Hell's Angels completed 48 missions without ever turning back from its assigned target.