Spaceflight Insider

Update: Antares’ AJ-26 engine failure

An AJ-26 engine being lowered into the E-1 Test Stand. Photo Credit: NASA

BAY ST. LOUIS, MS – On September 12, Spaceflight Insider had the opportunity to tour the Aerojet Rocketdyne facilities (Building 9101) located at NASA’s Stennis Space Center (SSC), in south Mississippi, and speak to Rocketdyne’s SSC General Manager, Mike McDaniel, regarding the May 22 2014 failure of an AJ-26 rocket engine during a test for Orbital Sciences Corporation (Orbital).


An AJ-26 at Orbital’s Facility at Wallops Island in January 2014. Photo Credit: Scott Johnson / SpaceFlight Insider

Spaceflight Insider previously reported on this engine failure, stating that the cause of the engine failure was unknown, and that the extent of damage to the SSC E-1 Test Stand, if any, was also unknown.

McDaniel was reluctant to classify the May 22 engine failure as an “explosion,” but did confirm that the AJ-26 “disintegrated” in “one frame” of the video (as yet unreleased) taken of the test and that there was damage to the E-1 Test Stand itself.

Based upon McDaniel’s statements, it appears that the damage to the Test Stand was not “structural,” at least not significantly, and consisted, primarily, of damages to conduits, piping and wiring.

McDaniel went on to indicate that the required repairs to the E-1 Stand are currently underway and that they are scheduled to be completed by October of this year.

When asked if the failure was due to a “fifty-year-old problem,” as opposed to a problem which resulted from “Rocketdyne modifications” to the engine, McDaniel responded in the affirmative.

August, 28, 2013, AJ-26 engine test on E-1 Test Stand. Photo Credit: NASA posted on SpaceFlight Insider

August, 28, 2013, AJ-26 engine test on E-1 Test Stand. Photo Credit: NASA

Two AJ-26 engines are used to power the first stage of Orbital’s Antares rocket. The AJ-26 is actually an NK-33 engine manufactured nearly fifty years ago by the former Soviet Union and originally intended for use on the failed Soviet N-1 moon rocket (there were four attempts to launch the N-1 between 1969 and 1972 – all ended in failure). Rocketdyne imports, refurbishes and upgrades the engines for use by Orbital.

Rocketdyne purchased over forty of the NK-33 engines in the 1990’s and Orbital has purchased 20 of those engines for use on Antares. Rocketdyne has upgraded the engines by adding, among other items, electronics and a gimbaling / steering capability systems.

The AJ-26 experienced one prior failure, in June of 2011, when an engine caught fire in the same E-1 Test Stand. The 2011 failure was determined to have been caused by a fuel leak resulting from “stress corrosion cracking of the 40-year old metal” contained in the engine.


Scott earned both a Bachelor's Degree in public administration, and a law degree, from Samford University in Birmingham, Alabama. He currently practices law in the Birmingham suburb of Homewood. Scott first remembers visiting Marshall Space Flight Center in 1978 to get an up-close look at the first orbiter, Enterprise, which had been transported to Huntsville for dynamic testing. More recently, in 2006, he participated in an effort at the United States Space and Rocket Center (USSRC) to restore the long-neglected Skylab 1-G Trainer. This led to a volunteer position, with the USSRC curator, where he worked for several years maintaining exhibits and archival material, including flown space hardware. Scott attended the STS - 110, 116 and 135 shuttle launches, along with Ares I-X, Atlas V MSL and Delta IV NROL-15 launches. More recently, he covered the Atlas V SBIRS GEO-2 and MAVEN launches, along with the Antares ORB-1, SpaceX CRS-3, and Orion EFT-1 launches.

Reader Comments

“…detailing that the cause of the engine failure was unknown…” Detailing of unknown details?

Change made.

Too engines with similar old age issues. Don’t look good. Hope they can catch all these issues on test stand.

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