How corrosive valves may have delayed the launch of the Boeing Starliner

How corrosive valves may have delayed the launch of the Boeing Starliner
How corrosive valves may have delayed the launch of the Boeing Starliner

Boeing says it is downplaying the source of the problem that delayed the launch of its new Starliner spacecraft this summer, attributing the problem to excess water and moisture causing the craft’s valves to remain at the front of flight. The company plans to study the problematic fuse in depth over the coming months and implement design changes, hoping to relaunch the Starliner in mid-2022.

Boeing’s CST-100 Starliner is a new passenger spacecraft, designed to transport astronauts to and from the International Space Station for NASA’s Commercial Crew Program. Before the Starliner can carry a crew, NASA wants Boeing to launch a successful flight of the craft with no one on board, to demonstrate that the spacecraft can safely perform all the movements of a typical launch.

But Boeing’s attempts to launch a Starliner drone encountered some speed bumps along the way. The company first launched the unmanned vehicle in December 2019, but a series of software problems prevented the spacecraft from reaching the correct orbit needed to reach the International Space Station, and flight controllers were forced to return the craft earlier than expected. Boeing was hoping to try again in early August 2021, throwing in another empty Starliner. But just hours before takeoff, the company discovered that a number of Starliner valves, used to transport the oxidizer – an essential propellant needed for flight – were not in the correct alignment.

In an update today, Boeing officials said 13 of the 24 oxidizer valves would not function properly, and would remain in the wrong position. While the Starliner was still on the launch pad, Boeing was able to release nine of the thirteen fuses, but four of them stubbornly failed to move properly. This prompted Boeing to return the Starliner to the factory for further inspection. Since then, engineers have dissected three of the valves, which helped them figure out what happened.


Boeing CST-100 Starliner before launch.
Photo by Greg Newton/AFP via Getty Images

“We’ve been able to eliminate a number of these things like bad wiring or hardware giving a false reading,” said Michael Parker, vice president and chief engineer at Boeing, at a news conference Tuesday.

Ultimately, Boeing believes that some of the oxidizer inside the valves has already leaked, causing the sticking. The valves are sealed with Teflon, and it is known that the oxidizer can sometimes leak through Teflon, according to the company. Boeing said Teflon was “chosen because it is compatible with the oxidizer” while other sealants are not. The theory is that as the oxidant escaped, it mixed with additional moisture and moisture at the launch site, causing the valves to corrode slightly. This wear is why Boeing can’t get the valves to move the way they want them to.

Since the launch delay, Boeing says it has fired 12 of the 13 stranded valves using a combination of additional heating and higher voltage. The Starliner team is deliberately keeping the valve stuck in the meantime, as they decide what kind of repairs they can put in place to make sure it doesn’t happen again. This can include adding additional heaters in the valves. In addition, Boeing removed two of the valves and sent them to NASA’s Marshall Space Flight Center, where they will undergo CT scans for more accurate analysis.

Perhaps most troubling is that Boeing still does not understand why the problem did not arise before the flight. The company says engineers conducted extensive testing on the valves before the vehicle was on the launch pad and the equipment worked as expected. “We have no indication that there is a problem with these valves,” said John Vollmer, Boeing’s Starliner program manager. Vollmer says Boeing added the oxidizer to the Starliner 46 days before the flight, but they expected to be able to add the fluid up to 60 days before the mission without any problems.

If Boeing flies the Starliner in the middle of next year, the company hopes to fly the vehicle with its first passengers by the end of 2022.[Our objective] is to safely resume the flight — and I insist on safety — as soon as possible,” Vollmer said. “So everything we’ve done so far, and the path that we’re developing in the future, is going to take us out there and back on the plane safely. Meanwhile, another commercial crew resource for NASA, SpaceX, has already begun transporting astronauts to and from the International Space Station on a regular basis, with another scheduled for October 31. When Starliner begins flying, the plan is for SpaceX to fly crews once a year, and Boeing to fly crews once a year.

When asked what would have happened if the Starliner had taken off with the fuses attached, Boeing said such a scenario would never have occurred, as flight controllers must check the fuses prior to flight. “It was one of those things that absolutely had to work, otherwise we wouldn’t fly,” Vollmer said. “So it’s not a problem if we’ve come forward and we didn’t know it. We knew perfectly well that these fuses would be in the correct position prior to launch. “

 
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