Boeing’s OFT-2 Starliner Flight Test Delayed Indefintely

Boeing’s OFT-2 Starliner Flight Test Delayed Indefintely

Launch of Boeing’s second flight test of its Starliner commercial crew spacecraft has been delayed indefinitely. The company and NASA announced today that Starliner will have to go back to the factory for further troubleshooting after 13 valves in its propulsion system failed to open hours before a scheduled launch on August 3. The root cause of the failure still is not understood.

Countdown to launch of the Orbital Flight Test-2 (OFT-2) mission was proceeding nominally on August 3. Weather was the only concern. Then suddenly about two hours before the expected launch, Boeing tweeted it was scrubbed, later explaining it was due to “unexpected valve position indications in the propulsion system.”

Boeing discovered that 13 of the 64 valves in Starliner’s service module were still closed. They must be open before launch.

At a media briefing today, John Vollmer, Boeing’s Vice President and Program Manger for Commercial Crew, said that after a week-and-a-half of troubleshooting, they still do not understand why.

The Aerojet Rocketdyne propulsion system has 24 oxidizer valves, 24 fuel valves, and 16 helium valves. All are the same design.

All 13 malfunctioning valves are oxidizer valves. They are on both the Reaction Control System (RCS) thrusters and the Orbital Maneuvering and Attitude Control (OMAC) thrusters needed for Starliner to reach orbit and maneuver once there.

When it was clear the problem could not be diagnosed while the spacecraft was still on the launch pad atop United Launch Alliance’s (ULA’s) Atlas V rocket, Boeing and ULA rolled it back to ULA’s Vertical Integration Facility (VIF) so the service module was more accessible.

Working on the Starliner spacecraft at ULA’s Vertical Integration Facility. Boeing tweet, August 9, 2021.

By yesterday, Boeing had managed to get nine of the 13 valves to open “after the application of electrical and thermal techniques,” but it was clear that fixing the remaining four and completing the detective work would require removing the spacecraft from the rocket and taking it back to the factory — the Commercial Crew and Cargo Processing Facility at Kennedy Space Center.

The leading theory right now is permeation of the teflon seals on the valves by the nitrogen tetroxide (NTO) oxidizer, which can happen when the NTO is exposed to moisture and turns into nitric acid.

The valves operated correctly when they were tested 5 weeks before launch. They are the same type of valve used for a Starliner Pad Abort Test in November 2019 and the OFT-1 mission in December 2019, all of which worked fine. Engineers do not understand what happened differently this time. Perhaps ambient moisture was trapped in the valve during assembly, or perhaps it was due to high levels of atmospheric moisture during a severe storm the night before the scheduled launch.

Boeing initially thought the heavy rains that night could have damaged the valves, but now are convinced that was not the case. The valve covers were disrupted and there was some water entry resulting in erroneous readings, but that is unrelated to the permeation, Vollmer said today. Boeing is working that as a separate issue.

The OFT-1 mission, an uncrewed test flight, did not go as planned due to software failures. Boeing decided to refly Starliner without a crew before putting astronauts aboard and OFT-2 was born. Starliner is a Public-Private Partnership between NASA and Boeing and the company is working under a fixed-price contract, meaning the entire cost of OFT-2 falls on Boeing. It took at $410 million pre-tax charge at the end of 2019 to cover the costs.

How much more Boeing will have to pay now is not clear. “I don’t know that I have a complete answer to that. I’ll work that with corporate. … An answer will be forthcoming. I just don’t have an answer today,” Vollmer said.

NASA’s Kathy Lueders, head of the human spaceflight program, and Steve Stich, head of the commercial crew program, are “disappointed” the launch is delayed again, but not “frustrated.” They and Vollmer stressed Starliner will not launch until it is ready, with safety, not schedule, as the highest priority.

No one would venture a guess as to when that day will come, but one complicating factor is there are other launches in the queue and Starliner will have to wait its turn. ULA is getting ready to launch a NASA mission, Lucy, to study the Trojan asteroids, which are in the same orbit around the Sun as Jupiter. That mission must launch during a very specific window of time, October 16-November 7.

Stitch said “we are definitely on the other side” of Lucy’s launch.

Starliner will dock at the International Space Station (ISS), so the launch must be timed to arrive when a docking port is available. ISS is a busy place, so that is no mean feat either. The Crew-3 Crew Dragon will launch on October 31, occupying one of the ports. Crew-2 is now docked and will return “in the November time frame,” which will free one up, but a cargo resupply mission is scheduled for late in the year. NASA’s ISS program manager Joel Montalbano said he would work with Boeing and ULA to find the best solution for everyone.

User Comments has the right (but not the obligation) to monitor the comments and to remove any materials it deems inappropriate.  We do not post comments that include links to other websites since we have no control over that content nor can we verify the security of such links.