Liquid propellant strap-on failure primary cause for Insat 4C crash

BANGALORE:The Failure Analysis Committee (FAC), constituted for investigating the failure of ISRO's Geosynchronous Satellite Launch Vehicle, GSLV-F02 mission from Satish Dhawan Space Centre (SDSC SHAR) Sriharikota, on 10 July, 2006 has submitted its report.

The 49 metre tall and 414 tonne GSLV comprises three stages. The first stage consists of a solid propellant motor and four liquid propellant strap-ons. The second stage is also a liquid propellant stage and the third is a cryogenic stage.

GSLV-F02 launch was the fourth in the series. All the three earlier missions (GSLV-D1, D2 and F01) were completely successful. The mission objective of GSLV-F02 was to place Insat-4C, an operational satellite into Geo-synchronous Transfer Orbit (GTO). About 55 sec into the flight, GSLV-F02 started deviating significantly from its nominal flight path resulting in the vehicle breaking up at 62 sec after lift-off. The debris fell into Bay of Bengal.

The 15 member FAC chaired by K Narayana, former Director of SDSC SHAR, with the participation of experts from academic and research institutions besides ISRO, has reviewed the performance of GSLV-F02 from lift-off to the end of flight. FAC had detailed deliberations for over 100 hours in several sittings and was assisted by eight specialist sub-committees examining the flight data of vehicle subsystems, manufacturing documents, inspection, calibration and test results, etc. Especially, the details related to the realisation of liquid propulsion stage of GSLV were closely scrutinized. Several tests simulating possible failure modes were also conducted to identify the exact cause.

FAC has concluded that the performance of all vehicle subsystems, except one strap-on stage was normal until 56.4 sec. The primary cause for the failure was the sudden loss of thrust in one out of the four liquid propellant strap-on stages (S4) immediately after lift-off at 0.2 sec. With only three strap-on stages working, there was significant reduction in the control capability. However the vehicle attitude could be controlled till about 50 sec. At the same time the vehicle reached the transonic regime of flight and the vehicle attitude errors built up to large values, resulting in aerodynamic loads exceeding the design limits thus leading to break up of the vehicle.

The thrust of the liquid engines used in the strap-on stages is precisely controlled by a set of regulators. Detailed analyses have indicated that in S4 engine the thrust control was not effective. Instead of stabilizing at 5.85 MPa (Mega Pascal) chamber pressure, it reached 7.11 MPa at 2.8 sec. This was much beyond the design limits and the engine failed at 0.2 sec after lift-off, that is 5 sec after its ignition.

Simulations and analyses of flight data and verification through calibration tests have led to the conclusion that the propellant regulator in the failed engine had much higher discharge coefficient in its closed condition. The reason for this could be an inadvertent error in manufacturing, which escaped the subsequent inspection, and acceptance test procedures. This regulator has functioned satisfactorily in all the previous 50 engines manufactured and tested so far, states an official release.

The larger flow of propellant led to higher operating pressure in the gas generator (4.7 MPa against design specification of 3.6 MPa). Due to this higher operating pressure of the gas generator, the water flow rate into it got reduced. The combined effect of larger flow of propellants and reduced flow of water led to a very high gas temperature of 1823 K against design specification of 900 K and pressure of 4.7 MPa against the design specification of 3.6 MPa. The very high operating pressure and temperature resulted in the structural failure of the gas generator. The consequent abrupt stopping of the turbo pumps that feed propellants at very high pressures to the engines led to loss of thrust of S4 engine. The water calibration tests conducted simulating the malfunction of the propellant regulator hardware could closely reproduce the flight phenomenon thereby confirming the larger flow area.

FAC has concluded that the design of GSLV is robust and recommended implementation of strict control on fabrication, inspection and acceptance procedures. Among others, FAC has recommended fabrication processes to be critically reviewed and updated. It has recommended for independent inspection of all critical dimensions of components and subassemblies by in-house agencies. Further, long duration hot test on one out of every 20 engines fabricated has been recommended to ensure that production process is under control. In addition, FAC has recommended strengthening the process of clearance of launch during Automatic Launch Sequence (ALS) phase.

FAC conclusions and recommendations have been accepted and necessary action has been initiated to implement all of them, the release adds.

Latest Reads
Andrew Jordan announced successor of AsiaSat's William Wade

Asia Satellite Telecommunications has announced the retirement of its executive director, president and CEO William Wade. He will serve his last day in the company on 1 November 2016 but will stay back as the senior advisor of AsiaSat until 31 March 2017.

Satellites Satellite Operators
GSAT-18 successfully launches, new capacity for DTH operators, TV channels

MUMBAI: Indian DTH operators, television channels, VSAT and digital satellite news gathering providers are a happy lot because of a development in Kouro French Guiana this morning. The reason: the successful launch of Arianespace’s Ariane 5 VA 531 rocket with its passenger, the Indian Space...

Satellites Satellite Launches
Bad weather pushes forward GSAT-18 launch

MUMBAI: The nation - and communication satellite trackers - will have to wait for another day. The Indian Space Research Organisation (ISRO) has announced that the launch of its GSAT-18 communications satellite has been delayed by a day. According to its launch partner, Arianespace, the flight...

Satellites Satellite Launches
ISRO's PSLV-C35 launches seven other satellites successfully

Around two hours after lift-off and after placing India’s weather satellite ScatSat1 in a polar sun synchronous orbit at 720 km, the Indian Space Research Organisation’s (ISRO’s) PSLV C35 rocket fired once again. Following that maneuver, it placed another seven satellites in orbit at an altitude...

Satellites Satellite Operators
ISRO’s PSLV-C35 takes off successfully, Scatsat1 launched

MUMBAI: It’s another feather in ISRO’s cap. The Indian space outfit seems to be going from success to success. Earlier this morning at 9:12 am, its latest mission the PSLV-C35 lifted off immaculately from the Satish Dhawan Space Centre in Sriharikota. Around 17 minutes later, its fourth stage...

Satellites Satellite Launches
ISRO to launch eight satellites using PSLV on 26 September

MUMBAI: It will be the second satellite launch this month for the Indian Space Research Organisation (ISRO). On 26 September 2016 at exactly 9:12 am the PSLV C35 will blast off from the first launch pad of the Satish Dhawan Space Centre in Sriharikota, Andhra Pradesh. It will mark the 37th...

Satellites Satellite Launches
XTreme-AsiaSat to provide 4K premium UHD content

4K-SAT, the Ultra-HD channel operated by Asia’s premier satellite operator Asia Satellite Telecommunications Co. Ltd. (AsiaSat), will be broadcasting premium extreme and outdoor content from XTreme Video on AsiaSat 4.

Satellites Satellite Operators
Govt satellite launches, including from India, to dominate future space market: Euroconsult

NEW DELHI: A major portion of satellites slated to be launched from 2016-2015 with launch mass over 50kg will be dominated by government satellites from countries like the US, Russia, India, China and Japan, according to Euroconsult.

Satellites Satellite Launches
India’s weather satellite INSAT-3DR launched successfully

India's Geosynchronous Satellite Launch Vehicle, equipped with the indigenous Cryogenic Upper Stage (CUS), on Thursday, successfully launched the country's weather satellite INSAT-3DR, into a Geosynchronous Transfer Orbit (GTO) in its tenth flight (GSLV-F05). The achieved orbit is very close to the...

Satellites Satellite Launches

Latest News

Load More

Sign up for our Newsletter

subscribe for latest stories