WASHINGTON — The loss of a solid rocket motor nozzle on the second flight of United Launch Alliance’s Vulcan Centaur last October was caused by a manufacturing defect that has been corrected as the company awaits certification of the vehicle by the Space Force.
The Cert-2 launch of Vulcan suffered an anomaly a little more than half a minute after its Oct. 4 liftoff when the nozzle of one of the two solid rocket strap-on boosters provided by Northrop Grumman fell off. The vehicle compensated for diminished thrust that resulted from the missing nozzle and still completed its mission.
In a March 12 media roundtable, Tory Bruno, president and chief executive of ULA, said the anomaly was traced to a “manufacturing defect” in one of the internal parts of the nozzle, an insulator. Specific details, he said, remained proprietary.
“We have isolated the root cause and made appropriate corrective actions,” he said, which were confirmed in a static-fire test of a motor at a Northrop test site in Utah in February. “So we are back continuing to fabricate hardware and, at least initially, screening for what that root cause was.”
That investigation was aided by the recovery of hardware that fell off the motor while in flight, which landed near the pad, as well as “trimmings” of material left over from the manufacturing process. ULA also recovered both boosters from the ocean so that they could compare the one that lost its nozzle to the one that performed normally. The defective hardware “just stood out night and day,” Bruno said. “It was pretty clear that that was an outlier, far out of family.”
That information has been passed along to the Space Force as part of the process to obtain certification for national security missions. “We’ve completed everything that you’re supposed to do,” he said, with that information provided last month. “Typically, it’s not a very long process in the past when vehicles are certified,” but deferred questions on the timeline of certification to the Space Force.
ULA’s next launch will be not of Vulcan but of Atlas, carrying a set of satellites for Amazon’s Project Kuiper constellation. That would be followed, once Vulcan is certified, of the USSF-106 and USSF-87 missions for the Space Force before switching back to Kuiper launches.
He projected ULA will perform about a dozen launches this year, split roughly evenly between Atlas and Vulcan and between national security and commercial missions. That includes Vulcan launches of Kuiper payloads, which could begin as soon as mid-year. An Atlas launch can carry 27 Kuiper satellites, he said, while a Vulcan can carry 45.
Bruno also addressed in the media roundtable a report by Bloomberg March 11 that the Department of the Air Force, in an annual assessment of contractor performance, had concluded ULA “has performed unsatisfactorily” on its National Security Space Launch contract. That report also said the Air Force was assessing if it was feasible to reassign launches awarded to ULA to an “alternate provider,” which would be SpaceX.
“When that was written, it was inaccurate. As we sit here today, it is certainly overtaken by events,” Bruno said of that Air Force report. Concerns about the production rate of the BE-4 engine has been resolved, he said, along with the solid rocket motor investigation.
Bruno said he would normally not talk about “improperly leaked” reports but wanted to do so to address its inaccuracies. “Besides its inaccuracies, I’m just a little bit suspicious that this was improperly leaked at this moment in time as I wait for my certification.”
