The launch of GSLV-D5 (with Indian Cryogenic Stage), scheduled for 1650 hrs on August 19, 2013, had to be called off due to a leak observed in the UH25 Fuel system of the Liquid Second Stage, during the last lap of the countdown. At the time of calling off the Countdown, the GSLV Vehicle was loaded with 210 tons of liquid and cryogenic propellants.
About 750 kg of UH25 Fuel had leaked out, leading to contamination of the area around the launch pad. It took 6 days of round-the-clock operations before the contamination could be reduced to the safe level to enable movement of the GSLV-D5 back to the Vehicle Assembly Building. The GSLV-D5 Launch Vehicle has been safely moved back to the Vehicle Assembly Building on the early morning of August 26, 2013. The Vehicle has been de-stacked.
Chairman, ISRO constituted a High Level Task Team on August 20, 2013, chaired by Shri K. Narayana, (former Director of Satish Dhawan Space Centre) to identify the cause of the leak and to work out an action plan for quick restoration of the Mission, taking into account the safety, reliability and life of the Liquid Second Stage and the four Liquid Strap-on stages, which were wetted with liquid propellants.
The leak is suspected to be in the lower portion of the propellant tank or the fluid lines between the tank and fuel filling system of the Second stage. Detailed investigation of the leak is underway.
The following action plan is put in place:
A new Liquid Second Stage (GS-2) is being assembled to replace the leaked-stage. All the four Liquid Strap-on Stages are being replaced with new ones. The First Stage (Solid) and core base shroud are being inspected and the elements that are affected will be replaced. The Satellite Assembly, Avionics Equipment Bay and the Cryogenic Stage will be preserved, following prescribed practices.
Based on current availability of hardware and components, the GSLV Vehicle assembly and checkout is expected to be completed at the Vehicle Assembly Building by the first week of December 2013 and the launch could take place by December 2013.