WASHINGTON — An Aerojet AJ-26 main engine undergoing acceptance testing for the inaugural flight of Orbital Science Corp.’s Taurus 2 rocket was badly damaged June 9 when a metal fuel line ruptured, causing the engine and test stand to catch fire, according to an industry source with knowledge of the mishap.

The fuel line that failed was part of the engine, not the test stand, the source said. The resulting fuel fire, which NASA said caused only minor damage to Stennis Space Center’s E-1 Test Stand in Mississippi, took approximately four minutes to extinguish.

The source, who asked not to be identified because he was not authorized to speak publicly on the matter, said the AJ-26  team investigating the mishap suspects a flaw in the metal used for that particular fuel line.

“If this looks like it’s a processing flaw when the metal was made, then the problem is probably just a one-off,” the source said.

The AJ-26 is a rebuilt NK-33, the Soviet-era liquid oxygen/kerosene engine Aerojet acquired in bulk in the 1990s.

Three AJ-26 engines have completed acceptance testing at Stennis and been delivered to Orbital’s Taurus 2 integration facility at NASA’s Wallops Flight Facility in Virginia. Two of those engines were intended to be used for an upcoming hold-down test of the Taurus 2’s first stage and then refurbished for the rocket’s second flight. The other engine already at Wallops was to have been paired with the now-damaged engine for the Taurus 2’s maiden launch, targeted for October.

That launch — a demonstration flight meant to help qualify the vehicle to launch cargo capsules bound for the international space station — now appears likely to slip at least a month since the next available engine still must undergo acceptance testing at Stennis, according to the source.

Orbital spokesman Barry Beneski acknowledged June 22 that the engine was damaged in a fire caused by a fuel leak but said details of the incident were still being investigated. He said a more extensive report on how badly the engine was damaged is expected the week of June 27.

Aerojet spokesman Glenn Mahone said June 24 the “fuel line leading into the engine” appears to be what caused the mishap, but cautioned that the investigation has not concluded. “Once the investigation is complete, we will make whatever changes or repairs we need to make and after that be prepared to go on with our testing,” he said.



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