The Failure Review
Oversight Board convened by International Launch Services (ILS) has
completed its initial review of an investigation into a failed Russian
rocket launch blamed on a Block DM upper stage.
The ILS board met last week in Moscow with members of the Russian
State Commission that investigated the Nov. 26 launch of a
Proton/Block DM vehicle from Baikonur Cosmodrome in Kazakhstan. The
failure left the ASTRA 1K satellite in a lower-than-planned orbit. The
ILS board also met with representatives from Khrunichev State Research
and Production Space Center, RSC Energia and hardware subcontractors.
The State Commission exonerated the three-stage Proton vehicle
built by Khrunichev. The failure was attributed to contamination in
engine components of the Block DM upper stage, made by Energia. The
propellant used was not cited as a potential root cause.
The fuel used in the Block DM, a synthetic kerosene known as
syntin that was developed by Energia, was tested before launch as part
of normal preflight processing, and after the failure. The fuel met
all Russian government specifications.
The anomaly occurred at the start of the second Block DM main
engine burn. There was excessive fuel in the main engine when it was
ignited, which led to extraordinarily high temperatures that destroyed
the engine, the commission found.
In the final report, the State Commission was unable to pinpoint a
single root cause for the failure. It identified two possible
scenarios for the fuel build-up, both attributed to contamination that
interfered with the normal operation of fuel metering components,
resulting in excess fuel in the gas generator.
In one scenario, “stray particles” clogged the manifolds through
which fuel is drained from the starting-fluid feed line after the
first burn. In the other, the contaminants clogged a valve designed to
supply fuel to the gas generator injector, causing the valve to leak.
“We may never know the root cause of the contamination in the
Block DM engine,” said Eric Laursen, ILS vice president and chief
engineer as well as chairman of the ILS review board. “It may have
been introduced during the manufacturing process, or following
acceptance of the engine, and could have affected the engine at any
time in the flight.”
The ILS review board is continuing its evaluation of the two
scenarios, pending the receipt of additional data from the State
Commission this week. The review board will also evaluate a corrective
action plan being developed by Energia to address the State
Commission’s concerns.
The State Commission made several recommendations in such areas as
Block DM testing and inspection for contaminants. The corrective
action plan is due to the commission by mid-February. The commission
in turn will review the plan to determine the validity and sufficiency
of the proposed remedies.
“Only when the ILS review board is confident that a robust plan is
in place, to ensure quality in newly manufactured as well as existing
hardware, will commercial flights using the Block DM upper stage
resume,” Laursen said.
