A routine quality assurance inspection has revealed a contamination problem with tubing in part of the core stage of NASA's first Space Launch System vehicle, Space News has reported.
The finding was unveiled by Don McErlean, panel member of the Aerospace Safety Advisory Panel (ASAP) at NASA’s Kennedy Space Center at a meeting on 17 May. McErlean commented that the committee had been briefed on a "late development" at the core stage, which was under construction at the Michoud Assembly Facility in New Orleans.
According to McErlean “a routine quality assurance inspection” of the core stage, had discovered contamination in tubing in the engine section, which hosts the vehicle’s four RS-25 main engines and associated systems.
The paraffin wax contamination, which is used to keep tubes from crimping during manufacture, is normally cleaned out before shipment.
McErlean said: “The prime contractor determined the vendor was not fully cleaning the tubes and it was leaving residue in the tubes. This was retained as a requirement in the prime contractor’s spec, but it was not properly carried out.”
Boeing is the prime contractor for the SLS core stage, but McErlean did not disclose the vendor who provided the contaminated tubing.
The contamination was initially found in a single tube, he said, but later checks found similar residue in other tubes. All the tubing in the core stage is now being inspected and cleaned, a process that is not straightforward he said, because of the “mass of tubing” in the engine section and also because cleaning is a “non-trivial process.”
Janet Anderson, a spokesperson at NASA’s Marshall Space Flight Center, said: “All core stage tubes have been reviewed by engineering for action or use as is. The tubes that have been determined to need further action are all in the process of being re-cleaned and inspected.”
McErlean did not comment if the tubing problem would affect the schedule for the completion of the core stage.
It has been reported that NASA had previously said they expected the core stage to be completed and shipped to the Stennis Space Center in Mississippi at the end of this year for so-called “green run” engine tests by mid-2019, after which it would go to the Kennedy Space Center to be prepared for launch on Exploration Mission (EM) 1.
Anderson commented that NASA is working with Boeing to determine the schedule effect the problem will have on the overall SLS programme.
“NASA is reviewing the impact of this decontamination effort on the Core Stage schedule, including delivery to the Stennis Space Center for green run testing and delivery to the Kennedy Space Center for EM-1 launch preparations,” he concluded.
The original article is available on the Space News website.
