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The testing of an engine for the giant SLS rocket will be delayed because engineers have found the remains of a washcloth in the ducts of the test stand at Stennis Space Center.
The investigation found the fibers belong to a cotton shop rag from a weld shop that had been involved with working on the LOX duct ID surface during manufacture. The roughened surface (of the duct) was where the fibers were observed to be hanging up on.
The investigation team reported that, under microscope inspection, a piece of the run duct stock showed metallic particles loosely adhered to the ID surface and embedded in the ‘machining’ groves. Several were easily dislodged and identified as ID surface material. “A tape sample was pulled from the same stock (after an identical cleaning process) and produced a rather large quantity of particles. This is an unacceptable condition and it was agreed that the entire run duct will need to be replaced or reworked (~30-ft of pipe),” added the investigation notes.
Replacing the duct will cause a several month delay in the test program. Fortunately for NASA, they have some wiggle room (for the moment), since the entire SLS schedule has already slipped a year to 2018.
Nonetheless, do not be surprised if this is only the first of many further delays.