Cause of GSLV-D3 failure analysed
The sudden stopping of the Fuel Booster Turbo Pump (FBTP) resulting in the non-availability of liquid hydrogen (LH2) supply to the thrust chamber of the main engine, caused the failure of the third developmental flight of Geosynchronous Satellite Launch Vehicle (GSLV-D3) conducted on April 15.
This was the conclusion arrived at by a failure analysis committee formed to look into the failure of the GSLV-D3 which was to test the indigenously developed Cryogenic Upper Stage (CUS).
According to the findings, which were further reviewed by a national group of eminent experts, the acceleration was comparable with that of earlier GSLV flights up to 2.2 seconds from start of CUS.
However, the thrust build up did not progress as expected due to non-availability of liquid hydrogen (LH2) supply to the thrust chamber of the main engine.
“The above failure is attributed to the anomalous stopping of Fuel Booster Turbo Pump (FBTP). The start-up of FBTP was normal. It reached a maximum speed of 34,800 rpm and continued to function as predicted after the start of CUS. However, the speed of FBTP started dipping after 0.9 seconds and it stopped within the next 0.6 seconds,” a press release from ISRO stated.
The committee attributed two reasons for the failure of FBTP: gripping at one of the seal locations and seizure of rotor and rupture of turbine casing caused probably due to excessive pressure rise and thermal stresses.
ISRO is now planning to conduct a series of confirmatory ground tests. After incorporating necessary corrective measures, the flight testing of Indigenous Cryogenic Upper Stage on GSLV is targeted within a year. In the meantime, the next two GSLVs would fly with the available Russian Cryogenic Stages, the release said.
The launch of ISRO’s Polar Satellite Launch Vehicle (PSLV-C15) has been scheduled for the morning of July 12.
The launch date originally fixed for May 9 was rescheduled after a marginal drop in the pressure in the second stage of the vehicle was noticed during mandatory checks carried out on the PSLV-C15 vehicle, according to the release.
PSLV-C15 is planned to launch India’s advanced remote sensing satellite Cartosat-2B, an Algerian satellite ALSAT-2A, two nano satellites NLS 6.1 and NLS 6.2 from University of Toronto, Canada and STUDSAT, a satellite built by students from seven academic institutions in Karnataka and Andhra Pradesh.