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.
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