Commission Determined Ruptured Exhaust Gas Conduit Led To Failure

A Failure Review Oversight Board (FROB) convened by International Launch Services (ILS) has cleared the Proton Breeze M launch vehicle to return to flight this summer, following its examination of test results and analysis regarding a redesigned engine component.

The Russian-built launch vehicle suffered a failure during the March 15 launch of the AMC-14 satellite from the Baikonur Cosmodrome. During that mission, the Breeze M upper stage shut down two minutes before the end of the planned second burn of its engine. As a precaution, the AMC-14 satellite was released into a lower-than-planned orbit.

A Russian State Commission investigated the failure, analyzed possible scenarios and reviewed the processes, hardware and systems related to the engine and its supporting systems. Both the Proton booster and the Breeze M upper stage are built by Khrunichev Space Center, which is the primary shareholder of ILS.

On April 21, the commission announced its conclusions: the failure was caused by a ruptured exhaust gas conduit, which led to a shutdown of the turbo pump feeding the Breeze M engine. The commission recommended a number of corrective actions, with the primary step being Khrunichev’s replacing the existing conduit with a thicker-walled conduit.

ILS assembled an independent FROB to review the Russian commission's findings in early May. Khrunichev subsequently performed additional modeling as well as component and certification engine testing to determine root cause and validate the recommended corrective actions. The FROB reconvened in Moscow last week to review the analysis and test results.

The FROB agreed that the root cause of the failure was that the conduit walls were thinner than the minimum specification, which when combined with other factors led to the rupture. Khrunichev adds it has successfully completed certification testing of a flight engine with the new conduit. The new conduit is being incorporated in all future engines.

The FROB was led by ILS Chief Technical Officer Jim Bonner. Membership included propulsion experts, members of the insurance community, and representatives of the customer for upcoming launches.

"The Khrunichev team, including Khimmash, manufacturer of the Breeze M main engine, demonstrated its commitment to mission success at every level," Bonner said. "We are confident that the root cause has been determined and that the corrective actions provide more than enough margin to prevent this from happening again.

"In addition to making this change in the engine, Khrunichev has moved forward with its overall quality initiative by completing a detailed quality assurance review, including an independent audit, in support of near-term Proton Breeze M missions," he added.

"I appreciate all the energy shown throughout this intensive and thorough process," ILS President Frank McKenna said. "We thank our customer participants and the insurance community for their contributions to the FROB... We anticipate that Inmarsat, which is the next scheduled commercial customer, will announce its selection of a launch date soon. So now the ILS-Khrunichev team must turn our focus toward making that and all other Proton launches successful."

ILS is scheduled to begin briefings in July for the underwriting and customer communities.

FMI: www.ilslaunch.com, www.khrunichev.ru