Falcon 9 breaks apart 139 seconds into the CRS-7 cargo mission to the ISS after a strut in the upper stage fails

SpaceX/Falcon 9 & Falcon Heavy

A Falcon 9 carrying SpaceX's CRS-7 Dragon cargo mission broke apart 139 seconds after launch on June 28, 2015, due to a failed support strut holding a helium tank inside the upper stage's oxygen tank. SpaceX found the 2-foot-long strut failed at just 2,000 pounds of force, barely one-fifth of its 10,000-pound design rating.

• Failed strut: ~2 feet long, 1 inch thick, rated 10,000 lbs but failed at 2,000 lbs
• Supplier component without independent acceptance testing; SpaceX committed to unit testing all future struts
• Helium leak into oxygen tank caused structural breach and catastrophic failure
• Return to flight: Not before September 2015 at earliest; company committed to finishing 2015 missions by year-end