WASHINGTON– As the independent review of last December’s test flight of Boeing’s CST-100 Starliner commercial crew vehicle nears conclusion, the company stated it will carry out more extensive testing to catch errors that slipped through on that flight.
In a Feb. 28 rundown at Boeing workplaces here, John Mulholland, vice president and program supervisor of Starliner, said the company is continuing an audit of the software on the spacecraft after 2 considerable errors were found throughout its two-day uncrewed test flight, while making strategies to perform more rigorous screening prior to future missions.
” We understand we require to enhance, especially with restoring trust with our client, and we promise our discipline and dedication to doing so,” he said. “We’re going to use additional rigor to systems engineering and software development.”
That test flight, called Orbital Flight Test (OFT), was shortened to two days, and a planned docking with the International Spaceport station cancelled, since a problem with a mission expired timer on the spacecraft kept it from performing an orbital insertion burn as planned soon after separation from the rocket’s upper stage. An investigation found that the spacecraft’s timer was initialized at the incorrect time during the launch countdown, triggering it to be off by 11 hours.
At a Feb. 6 conference of NASA’s Aerospace Safety Advisory Panel, members stated they had been briefed about a 2nd software application problem, called a “valve mapping error,” for the thrusters on the Starliner’s service module
Mulholland stated that the timer issue was not fixed in prelaunch screening with United Launch Alliance because the business split testing of the spacecraft into different phases of the mission. For launch, the tests ended instantly after spacecraft separation, and thus did not spot the timer offset. “If we would have run the incorporated test with ULA through the first orbital insertion burn timeframe, we would have seen that we would have missed out on the orbital insertion burn since the timing was corrupt,” he stated.
Going forward, he said Boeing will test Starliner operations from launch through docking, and from undocking to landing. “The team thought at the time it was more sensible to break these objective stages into portions and do a lot of screening in those smaller portions,” he said.
The valve mapping problem involved the use of what Mulholland called a “legacy propulsion controller” on the service module. One mapping, which determined thrusters and valves in software application, is required when the service module is connected to the team module while another is needed for use after separation.
” Unfortunately, that requirement was not gotten” in interface control documents for that propulsion controller, he stated. “The only thing that was gotten was the one jet map for the incorporated spacecraft and we missed the jet map that was needed for the service module after separation.”
That oversight wasn’t caught in testing due to the fact that the controller itself was not offered when the software was checked because it was being utilized for a service module hotfire test. The emulator used in its place didn’t allow engineers to identify the missing out on jet mapping.
In the future, Mulholland stated they’ll more closely study hardware requirements for screening. “We’re not just going to define exactly what tests have to be carried out, but we’re going to require that specify precisely what the hardware setup requires to be in the laboratory,” he stated.
At a Feb. 7 briefing, Boeing revealed it would examine all the Starliner software application, accounting for about one million lines of code. Mulholland stated that audit had finished all of the “high” and “medium” products in regards to complexity of their reasoning, and the majority of the low-complexity ones. That audit found a couple of spaces in screening that engineers are now following up on, however no proof of additional software application abnormalities.
Asked why some testing was neglected, Mulholland stated it wasn’t a matter of cost-cutting or otherwise taking intentional shortcuts. “They did an abundance of screening and in particular areas we undoubtedly have gaps to go fill,” he said of the Starliner team.
Other aspects of Starliner performed well throughout the shortened test flight with only minor technical problems. Engineers are still investigating a communications issue that prevented initial efforts to recover the spacecraft after the timing issue kept it from performing its orbit insertion burn. That problem happened 37 times during the mission, all however one over the same area, northern Europe and Russia, he stated, with the sole exception a known case where the antenna incorrectly believed it was locked.
Mulholland said it’s not clear yet if the issue is caused by interference special to that area or if the particular choice of antennas for interacting with relay satellites made it more prone to regular disturbance. “We really require to look a bit deeper into that before we provide any final results,” he stated.
The investigation into the interactions issue is not likely to be completed prior to an independent evaluation team provides its outcomes. While the rundown remained in development, NASA revealed another media briefing was set up for March 6 to discuss the findings from the rest of that independent team’s work, with both NASA and Boeing personnel arranged to get involved.
Mulholland decreased to speculate on whether a 2nd OFT mission should be flown prior to performing a crewed Starliner flight, or when that flight would take location. “The timeframe between now and the next flight is going to be identified by us methodically working our way through that audit procedure,” he stated, consisting of any issues it might yet uncover.
A choice on whether the next flight will be uncrewed or crewed, he included, will ultimately be made by NASA and not Boeing. “NASA is doing the assessment of that now, and it’s their decision on which flight will be next.”
Congress will be carefully seeing that decision and other elements of NASA’s total industrial team program. “It is absolutely something we’re following and concerned about,” said Rep. Kendra Horn (D-Okla.), chair of your house area subcommittee, in a Feb. 28 interview prior to the Boeing rundown.
” We’re looking at something that has slipped. There have been problems with both of the contractors,” she said, a referral to SpaceX, the other business team company, which suffered the loss of a Crew Dragon spacecraft last April during screening for an organized in-flight abort test. “That’s why it is necessary that NASA have that ability to direct and oversee and have gain access to at all parts of this procedure.”