ASAP reviews Boeing failure, positive SpaceX success ahead...
- by NASASpaceFlight.com
- Jul 30, 2018
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Another area of discussion related to the COPVs, Composite Overwrap Pressure Vessels, that will be used in the Falcon 9 rocket, new COPV designs set to debut on the uncrewed DM-1 mission with Falcon 9 core B1051.
According to ASAP, “We’ve learned a lot this week about a very detailed and structured approach for certification of the COPVs used on the SpaceX design. There’s been a lot of testing and a lot of follow-up and investigations to try to understand the physics of things like what could cause potential ignition mechanisms or other failure mechanisms.
“And the panel really wants to commend the deep dive team [for their work], but we do recognize that there’s still a lot of work to do. The jury is still out on this. And we look forward to seeing what the results of what this work will mean in terms of final characterization of the risk and whether that risk will be acceptable. And if not, what further risk mitigation measures might be necessary concerning those COPVs.”
Another area to watch – one that ASAP believes is on course to a “satisfactory conclusion” – relates the Falcon 9’s Merlin 1D engines and their upgrades for crew configuration. “The first two engine started to go through the qualification procedure, and upon tear down there were observations of some anomalies in the hardware that were considered potentially dangerous – certainly not desirable,” noted the ASAP.
“There was a program undertaken to try to modify the design and to correct these anomalies. SpaceX and NASA agreed on a requalification plan that actually includes six engines – two ground test configurations and one in-flight test configuration.”
The Block 5 Falcon 9 takes a Crew Dragon to space during one of SpaceX’s upcoming Demonstration Missions. (Credit: Nathan Koga for NSF/L2)
As work on this issue continued, SpaceX developed two short-term corrective actions that are deemed worthy and safe to fly on the uncrewed DM-1 mission. At the same time, SpaceX began designing and implementing two longer-term solutions to the anomaly seen on the test stand.
The ASAP noted that the two short term actions could also potentially be used on the crewed DM-2 flight should they prove safe enough during post-flight and post-test stand teardown and inspections. A decision on whether those short-term actions can fly on the crew demonstration mission will not be taken until a better understanding of the short-term actions are known.
Nonetheless, the ASAP is “optimistic that those courses of action will result in a satisfactory conclusion.”
Final Certification – a discussion:
Through all of this, the ASAP was primarily quite pleased with the overall status of the Commercial Crew Program and the current final drive toward certification of the products being delivered by the two providers.
There was a specific note that no schedule pressure was observed during the latest round of oversight meetings, with both providers acutely aware of the safety and risk factors involved and that those take precedence over any perceived/looming desire to see the programs up and running.
With a Starliner docked safely to ISS, a crew Dragon approaches the Station using the C2V2 radio. (Credit: Nathan Koga for NSF/L2)
However, “as we approach the certification milestones, we still have to be assured that not only will the component hardware design be ready for certification, but that the overall integrated risk of human spaceflight missions can be effectively managed in both the design of the hardware and the operational practices of using the hardware,” noted the ASAP.
To that end, one ASAP member took time to discuss, in detail, what certification of these products actually means. During his statements, Dr. Don McErlean sought to clarify for everyone what the final certification process entailed – as it is often referred to as a “paper process.”
“It needs to be noted by everyone, and we’re especially interested in making sure that all of the external stakeholders realize this, that while the concluding process of certification has sometimes been described as a paper process, that is really just a shorthand clarification and in reality it could not be further from the truth,” noted Dr. McErlean.
In reality, the process is as follows. “In a certified design, the design agent – the contractor or partner in this case – performs the design and in the certification plan, the design agent and the certification agency (NASA) agree on the submittal of certification evidence.
“This could be measurements, it can be test data, it can be analysis, but it almost always involves the submittal of detailed technical data, not simply paper descriptions or forms. Sometimes it involves witness testing and sometimes it involves physical inspection. But it almost always wraps around important technical submittals.
“The technical arm of the certifying agency – NASA in this case – then reviews and analyzes that data to validate that in fact the design meets the stated requirements with the expected margins. This validation activity extends to many aspects of the design and also to the operation of the integrated mechanism or the entire system. Once the certifying agency agrees that these validations are correct and acceptable, then it certifies the design and then we can state that we have run to conclusion of the certification process.
“It is this technical review of certification data and products which in fact constitutes the work required to conclude the certification process, and if successful, results in the agency in fact certifying the design.
“In short, we want everyone to realize that this is not a paper sign off process. It involves considerable detailed technical activity by both the certifying agency – NASA in this case – and the design agency or the contractor or partner as well.
“In addition, it should be stated that the design is certified for a given range of operations. This is assumed as part of the process. And we all realize that should his range of operations be significantly exceeded, the data would have to be reevaluated and reexamined to determine if the design was adequate for the new regime.
#BREAKING @NASA news! I will be at @NASA_Johnson on 8/3 to announce the astronauts assigned to the first crews launching on American-made spacecraft from American soil since the retirement of the Space Shuttle Program.https://t.co/SA6cj81ah5
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