State commission tentatively finds malfunction of Soyuz fuel dump valve - source
MOSCOW. Oct 12 (Interfax) - A valve malfunction may have caused the accident involving the first stage of the Soyuz-FG rocket that was launched from Baikonur on Thursday, an informed source told Interfax.
"The state commission has tentatively established a malfunction of the fuel dump valve of the rocket's oxidizer tank: exhaust gas coming from the valve pushes a side section away from the center section. The valve appeared to be defective and failed to function," the source said.
The valve passed the preflight check, he said. "It was opened before the launch, and closed afterwards consistent with the procedure," the source said.
Once the rocket is fueled, the valve dumps redundant oxygen. "It is closed several minutes before the launch. It is supposed to open after the side section separates from the central section, but that did not happen," the source said.