Sept. 23 -- No longer in production, the 53E heavy-lift helicopters are a case study of the broader fatigue affecting the U.S. military’s air fleet. After two post-Sept. 11 wars and recent Pentagon belt-tightening, the Sea Dragon and Super Stallion are “worn out and in need of replacement,” says Todd Harrison, a defense analyst at the Center for Strategic and International Studies, a Washington think tank. But Sea Dragons are scheduled to continue to fly until at least 2025, and Super Stallions until at least 2029. The obvious question is why. Bloomberg Businessweek's Paul Barrett has more on "Bloomberg Markets."