NASA Report Links 2014 Antares Rocket Explosion to AJ26 Engine Problem

Summary: NASA's Independent Review Team Executive Summary, released Oct. 30, links the 2014 Antares rocket explosion to an AJ26 engine turbopump problem.

Antares rocket explosion Oct. 28, 2014, at Wallops Island, Virginia: NASA/Joel Kowsky, Public Domain, via Wikimedia Commons

An Executive Summary publicly released by NASA’s Independent Review Team (IRT) on Oct. 30, 2015, identifies an AJ26 engine’s turbopump as the “proximate cause” of the Antares rocket explosion on Oct. 28, 2014, and recommends “a greater level of due diligence for major system components.”

The summary links the Antares rocket’s loss of thrust and crash near its launch pad just over 15 seconds after liftoff to damage to the AJ26 rocket engine in the Main Engine 2 position as the result of a friction-caused explosion in Main Engine 1’s liquid oxygen turbopump. Frictional rubbing between rotating and stationary components in the seal package of the turbopump’s hydraulic balance assembly ignited the explosive fire that destroyed the rocket and its cargo and damaged the launch pad and its adjacent structures.

NASA IRT’s nearly year-long investigation suggests three potential root causes, singly or in combination, for the fire and explosion. One possibility could be intricate, sensitive designs that interfere with reliable load bearing and open the turbopump’s hydraulic balance assembly and thrust bearing to oxygen fires. Acceptance testing established for the AJ26 engines was insufficient to detect this “inadequate design robustness.”

A second possibility could be the presence of silica and titanium, though not in gross levels, as foreign object debris prior to crash impact.

A third possibility could be defective manufacturing. The investigators discovered a machining defect in the engine’s turbopump.

AJ26 engine on transportation/processing skid: NASA IRT Orb-3 Accident Investigation Report Executive Summary, figure 3, page 4, Public Domain, via NASA

Orb-3 Accident Investigation Report Executive Summary makes six recommendations for improvement of NASA’s Commercial Resupply Services for cargo delivery to the International Space Station (ISS). The first four concern bureaucratic efficiency, flow of information, and consistent risk level assessment. The fifth notes “the criticality and complex integral role the engine plays in launch vehicle mission success” and emphasizes due diligence with respect to major system components. The sixth point recommends that both NASA and cargo delivery service providers attain sufficient expertise, from design through failure history, in all launch vehicle systems.

Six technical findings indicate the presence of foreign object debris and insufficient testing for design and workmanship flaws. Eight programmatic findings address varying perceptions of acceptable risk, communication shortfalls stemming from barriers imposed by proprietary information, and insufficient knowledge of engine design, failure history, and operation on the part of Orbital ATK, operator of the Antares rocket, and Aerojet-Rocketdyne, supplier of AJ26 engines.

Seven technical recommendations emphasize thoroughly qualifying and testing of RD-181, the engine that is replacing AJ26, as well as better placement of better sensors for testing engine performance, verification of required cleanliness for engines and other critical components, robust and verifiable barrier approach to reduce likelihood of moisture, and “greater insight into and understanding of engine design, certification, and operation” by both NASA and Orbital ATK, operator of the Antares rocket.

The AJ26 engines are former NK-33 rocket engines, designed and manufactured in Russia for use in the four failed launches of the Soviet N1 moon landing program from 1969 to 1972. American rocket motor manufacturer Aerojet-Rocketdyne modified the engines and renamed them as AJ26.

Orb-3 Accident Investigation Report Executive Summary self-identifies as “an overview of publicly releasable findings and recommendations” in lieu of the Independent Review Team’s official report, which presents restricted information under U.S. International Traffic in Arms Regulations (ITAR) and corporate proprietary details.

aerial view of Wallops Island launch facilities, Oct. 29, 2014, in aftermath of Oct. 28 Antares rocket explosion; scorched ground to right of launch pad (center right): NASA/Terry Zaperach, Public Domain, via Wikimedia Commons

Acknowledgment

My special thanks to talented artists and photographers/concerned organizations who make their fine images available on the internet.

Image credits:

Antares rocket explosion Oct. 28, 2014, at Wallops Island, Virginia: NASA/Joel Kowsky, Public Domain, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Orbital_ATK_Antares_Launch_(201410280037HQ).jpg

AJ26 engine on transportation/processing skid: NASA IRT Orb-3 Accident Investigation Report Executive Summary, figure 3, page 4, Public Domain, via NASA @ https://www.nasa.gov/sites/default/files/atoms/files/orb3_irt_execsumm_0.pdf

Wallops Island launch facilities in aftermath of Oct. 28, 2014, Antares rocket explosion: NASA/Terry Zaperach, Public Domain, via Wikimedia Commons @ https://commons.wikimedia.org/wiki/File:Aftermath_of_Antares_Orb-3_explosion_at_Pad_0A_(20141029b).jpg

For further information:

Klotz, Irene. "NASA must take more care about rocket parts after accident: probe." Reuters > Technology. Nov. 3, 2015.
Available @ http://www.reuters.com/ article/2015/11/03/ us-space-orbital-accident-idUSK CN0SS2SK20151103

Mazza, Ed. "NASA Releases Stunning New Images Of 2014 Antares Rocket Disaster." HuffPost Science. Nov. 5, 2015.
Available @ http://www.huffingtonpost.com/entry/antares-explosion-photos_563afa72e4b0307f2cac1c89

NASA. "NASA Releases Orbital ATK Accident Review Summary." PDDnet > News. Oct. 30, 2015.
Available @ http://www.pddnet.com/news/2015/10/nasa-releases-orbital-atk-accident-review-summary

NASA Independent Review Team. "Orb-3 Accident Investigation Report Executive Summary." NASA. Oct. 9, 2015.
Available @ https://www.nasa.gov/sites/default/files/atoms/files/orb3_irt_execsumm_0.pdf