Analysis on GSLV-D3's failure complete

Non-availability of liquid hydrogen supply to the thrust chamber of the main engine could have resulted in failure of the third developmental flight of Geosynchronous Satellite Launch Vehicle from Sriharikota on April 15, a failure analysis committee has found.

The flight of GSLV-D3 primarily meant for testing of indigenously developed cryogenic upper stage (CUS) had failed to achieve the mission objectives following which ISRO had instituted a two-tier process to carry out an in-depth analysis of the flight performance and identify the causes of the failure and recommend corrective measures.


As per review of the findings by the ?National Group of Eminent Experts?, though the ignition of the CUS main engine and two steering engines were confirmed normal, the thrust build up did not progress as expected ?due to non-availability of liquid hydrogen (LH2) suppy to the thrust chamber of the main engine?, an ISRO release said.

The 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,? it said.

Two plausible scenarios have been identified for failure of FBTP, gripping at one of the seal locations and seizure of rotor and a rupture of turbine casing caused probably due to excessive pressure rise and thermal stresses, it said.

As per the review, following a smooth countdown, the lift-off took place at 1627 hrs (IST) as planned. All four liquid strap-on stages (L40), solid core stage (S139) and liquid second stage (GS2) functioned normally, it said.