SpaceX Crew Dragon Challenges: Welds, Cracks & Water Seepage

SpaceX Crew Dragon Weldment Structure (Credit: SpaceX)
SpaceX Crew Dragon Weldment Structure (Credit: SpaceX)

Excerpted from, “NASA’s Commercial Crew Program: Update on Development and Certification Efforts,” NASA Office of Inspector General, Report No. IG-16-028, September 1, 2016

SpaceX’s CCtCap contract initially included 18 milestones ranging from establishment of the original requirements baseline to final vehicle certification. During the first year of the contract, SpaceX and NASA agreed to separate SpaceX’s Propulsion Module Testing and Critical Design Review into multiple segments, which increased the total milestones to 21.20

As of June 2016, SpaceX had completed eight milestones (38 percent), five less than planned under the original schedule, and received $469 million (18 percent) of the total contract value. Of the 18 SpaceX milestones, five related to specific NASA program requirements:

  1. Certification Baseline Review,
  2. Design Certification Review,
  3. Flight Test Readiness Review,
  4. Operations Readiness Review, and
  5. Certification Review.

As with Boeing, these reviews are intended to ensure SpaceX has developed its transportation system design, defined its plan and schedule, and demonstrated that the system meets NASA requirements for one uncrewed and one crewed flight test leading up to final certification for operational flights to the ISS (click here for detailed descriptions of these review).

The dates for all of these milestones have also been extended, which has in turn delayed the two test flights. As of June 2016, SpaceX had not revised its schedule and was still planning its first certified crewed flight in December 2017. However, given the delays in achieving milestones necessary to receive certification, we believe it highly unlikely SpaceX will meet this goal.

As of July 2016, SpaceX has completed four significant milestones:

  • Certification Baseline Review. For this review, baseline requirements were confirmed to bein line with NASA guidance; the plan and schedule for completing design, development, test,and evaluation and certification for the system was defined; and top safety, technical, cost, and schedule risks were defined. SpaceX completed this milestone in December 2014 after a1-month delay.
  • Initial Propulsion Module Testing. This test of a flight-representative spacecraft propulsion system was conducted in October 2015 after a 6-month delay.
  • Critical Design Review, Delta Critical Design Review, and Delta Critical Design Review 2. These reviews are intended to ensure the Falcon 9/Crew Dragon design satisfied all applicable requirements; assess the maturity of the system to determine whether it is appropriate to proceed to fabrication, assembly, integration, and testing; and secure NASA approval of the contractor’s product verification and validation plans. SpaceX completed the first part of the review, which focused on the design of its launch vehicle and uncrewed ground systems, in November 2015 after a 5-month delay. It completed the second part, which focused on the capsule and mission operations in December 2015 as scheduled. SpaceX is planning to undertake the third part of the review, which will focus on any remaining Dragon components, an updated seat design, and crewed ground systems, in August 2016. In total, SpaceX anticipates completing all three components 13 months later than originally planned.
  • Propulsive Descent Test Complete. This test of the Pad Abort Test Vehicle to perform controlled propulsive burns in a dynamic environment was completed in December 2015 after a 3-month delay.

SpaceX also has not yet completed all milestones associated with Critical Design Review – a stage in the development process that often reveals shortcomings a contractor must address before it proceeds with full-scale fabrication, assembly, integration, and testing of its capsule. SpaceX officials attributed the delays to capsule design challenges, specifically switching from a design that used a ground-based landing to a water-based landing design in the first year after contract award. This resulted in significant challenges, including complications with vendor components and the effectiveness of the integrated landing system designed to ensure parachutes work and the capsule does not take on excessive water after landing in the ocean.

In addition, SpaceX stated it had underestimated the number of interfaces to the weldment and radial bulkheads, which also resulted in design delays.21 The Government Accountability Office recently reported that several of the SpaceX key subsystem vehicle designs are not yet mature, finding that SpaceX does not plan to complete seat designs until mid-2016.22

Once SpaceX completes the final phase of Critical Design Review, it must meet several additional milestones, including

  • the uncrewed flight test currently scheduled for December 2016 (originally scheduled for March 2016);
  • the Design Certification Review in January 2017 (originally scheduled for July 2016);
  • a Flight Test Readiness Review in March 2017 (originally scheduled for September 2016);
  • the crewed test flight in April 2017 (originally scheduled for October 2016); and
  • the Operations Readiness Review in July 2017 (originally scheduled for January 2017).

NASA hopes to conduct SpaceX’s final certification review in October 2017 (originally scheduled for April 2017).

NASA Program officials anticipate SpaceX will encounter additional delays on the path to certification. For example, in January 2015, the tunnel that provides a passageway for astronauts and cargo between the Dragon and the ISS was reported to have cracked during the heat treatment phase of the manufacturing process. As a result, SpaceX delayed qualification testing by approximately one year to better align the tests as SpaceX moves toward certification. SpaceX has also experienced ongoing issues with stress fractures in turbopumps that must be resolved prior to flight.23

Additionally, SpaceX has not yet completed parachute system level testing which may reveal issues that would require redesign that could further delay the test flights. Accordingly, we anticipate additional schedule slippage and do not expect certified flights by SpaceX earlier than late 2018.

As stated earlier, SpaceX is scheduled to complete the final phase of its Critical Design Review in August 2016. As part of this review, SpaceX and NASA will assess lessons learned from the SpaceX’s failed June 2015 cargo mission. According to the Associate Administrator for Human Exploration and Operations Mission Directorate, the accident provided an opportunity to gain a better understanding of weaknesses in SpaceX’s rocket design, which in turn can be used to inform its crew design. Although SpaceX officials told us that the mishap has not delayed its crew development efforts because it had built sufficient margin into the schedule, they also noted the lack of margin remaining to accommodate any additional unexpected issues that may arise.

20 The total contract cost did not increase as a result of the increase in total number of milestones.
21 A weldment is formed by welding together an assembly of pieces. For the SpaceX vehicle, the radial bulkheads attach to the lower part of the weldment and separate the housing for thrusters, propellant tanks, parachutes, and other vital systems.
22 Government Accountability Office, “NASA: Assessments of Major Projects” (GAO-16-309SP, March 30, 2016).
23 A turbopump provides fuel to the main combustion chamber of an engine.