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        Faulty Metal Brace Likely Doomed SpaceX Falcon Rocket, Musk says

   by Reuters

   A faulty metal brace in an unmanned SpaceX Falcon 9 rocket likely
   triggered the explosion that destroyed the booster minutes after
   liftoff from Florida last month, company chief Elon Musk said on
   Monday.

   The June 28 accident, which destroyed a load of cargo destined for the
   International Space Station, was the third botched resupply run within
   eight months. An Orbital ATK rocket explosion claimed a Cygnus cargo
   ship in October and a Russian Progress freighter failed to reach orbit
   in April.

   SpaceX founder and Chief Executive Musk said Falcon rocket flights will
   not resume until September at the earliest. The company also plans to
   delay the debut flight of its heavy-lift Falcon rocket from this year
   to spring 2016.

   A defective brace, or strut, holding a bottle of helium in the Falcon 9
   needed to pressurize the upper-stage engine's liquid oxygen tank, was
   the most likely cause of last month's accident, Musk said.

   He said the strut, from a vendor he declined to identify, was built
   from steel certified to withstand 10,000 pounds (4,536 kg) of force but
   apparently failed at 2,000 pounds (907 kg) of force, Musk said.

   "It looks like the key strut that holds down one of the helium bottles
   failed. As a result, the helium bottle would have shot to the top of
   the tank at high speed," Musk told reporters on a conference call.

   "It failed five times below its nominal strength, which is pretty
   crazy," he said.

   SpaceX not only intends to buy new struts, most likely from a different
   vendor, but test each one prior to installation in the rocket's tanks,
   Musk said.

   SpaceX had successfully flown its Falcon 9 rocket 18 times since its
   debut in 2010 before the June 28 failure. During those flights,
   thousands of similar struts apparently worked with no issues.

   "We have been able to replicate the failure by taking a huge sample,
   essentially thousands of these struts, and pulling them. We found a few
   that failed far below their certificated level. That's what led us to
   think that there was one just far below its rated capability that
   happened to be at the wrong place at the wrong time," Musk said.

   The results are preliminary, he added.

   In addition to the bad strut, SpaceX is looking for other issues that
   may have caused or contributed to the accident, as well as any
   potential problems that could affect future flights.

   "This is the first time we've had a failure in seven years, so I think
   to some degree the company as a whole became maybe a little bit
   complacent," Musk said.

   The company has a backlog of more than 50 rocket launches, worth about
   $5 billion, for commercial companies, NASA and other agencies.
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References

   1. http://www.voanews.com/content/faulty-brace-doomed-spacex-falcon-rocket-elon-musk/2871387.html