The Interdepartmental Investigation Board arranged by Rosaviakosmos headed by A.S. Koroteev, Director of M.V. Keldysh Investigation Center, Academician of the Russian Academy of Science, completed its work and concluded that accident with Astra-1K launch on 26.11.02 was due to failure of Upper Stage DM3 main engine 11D58M at the second burn resulting in launching Astra-1K SC into off-nominal orbit.
The specialists from Rosaviakosmos, S.P. Korolev RSC Energia, M.V. Khrunichev GKNPTs, Machinery TsNII, S.P. Korolev RSC Energia Experimental Machinery Factory (ZEM), NPO “Tekhnomash”, M.V. Keldysh Investigation Center, Voronezh mechanical factory, TM KB Soyuz, FKTs Baikonur, Krasnoyarsk Machinery Factory, Chemical Automatics Design Bureau (KB), TsENKI, Chemical machinery NII, Russian Federation Defense Ministry organizations.
As a result of the work the Board stated that main engine 11D58M failed at the second burn due to the off-nominal start-up process caused by excessive fuel in the gas-generator at the initiation of combustion occurred because of occasional plugging of the fuel drainage pipelines after the first burn of the engine or gas-generator fuel supply valve leakage due to this plugging.
According to the conclusion of the Board this case occurred the first time for the entire operation period of the Upper Stages of DM type. This failure is of occasional, single nature.
Considering great positive history of Upper Stage DM operation with engine 11D58M (over 200 successful launches), the Board stated that it is possible to continue manufacturing and launching the Upper Stages of DM type.
In order to prevent such cases in the future the additional measures are implemented to control the cleanliness of the engine hydraulic pipelines.
The successful launch of Upper Stage DM with three SC of GLONASS system as a part of Proton-K ILV performed on 25.12.02 confirmed that the conclusion of the Board was correct.
