spacetoday.net: Ruptured gas duct blamed for Proton failure

Posted: Tue, Apr 22, 2008, 7:29 AM ET (1129 GMT)
Proton launch of Thor 5 (ILS)

A Russian commission has concluded that a ruptured gas duct caused the premature shutdown of the upper stage of a Proton rocket launched last month, International Launch Services announced Monday. Investigators concluded that the duct, which runs from the gas generator to a propellant pump turbine in the Breeze M upper stage, ruptured late in the second burn of the stage on the March 15 launch, causing the engine to shut down prematurely and ultimately stranding the AMC-14 payload in a transfer orbit; the satellite's owner declared the satellite a total loss earlier this month. The duct likely ruptured because of the combined effects of duct wall erosion, high temperatures and prolonged low frequency pressure fluctuation in the duct, according to investigators. The commission identified a number of corrective actions for both that particular failure as well as steps to improve the reliability of the Breeze M main engine. No timetable for making those changes and returning the vehicle to flight were announced.