Chandigarh: Inducted to serve as India's main battle tank just over three years ago, the Army's fleet of Russian-built T-90s have run into serious trouble.

The problems include critical flaws in its fire control system, availability of ammunition and, what military officers said, was avoidable overuse during training exercises, rendering many tanks in need of overhaul.

According to Jane's Defence Weekly, the tank's continuing technical flaws are "adversely impinging on the Indian Army's operational preparedness."

Confirming the Jane's report, senior Army officers told this newspaper that the French Catherine thermal imaging (TI) camera, which gives the T-90's Belarussian (Peling IG-46) night sight its 3 km range and higher accuracy, is not "adequately tropicalised" and hence prone to malfunctioning in the extreme heat of the Rajasthan desert region, where temperatures inside the MBT routinely average between 55ºC and 60ºC.

During repeated manoeuvres in the Thar Desert, where the T-90s will ultimately be deployed in the event of an outbreak in hostilities, prolonged use under high temperatures had already "knocked out" between 80 and 90 of the Catherine TI cameras, rendering the FCS "unserviceable." The officers said that repeated efforts to correct the problem had been without success.

The TI cameras are the crucial "eyes" of the tank's systems. At Rs 2 crores each, the Catherine TI system comprises almost one-sixth of each T-90's total cost of Rs 11.75 crores.

Up-graded - In 2007 a further 347 un-assembled kits were ordered, but have some further modifications. The Kontakt-5 has been replaced with the superior Kaktus ERA. To cope with India’s harsh heat and its effects on tank crews, Israeli firm Kinetics Ltd’s environmental control system’s have been installed to provide a constant cooling of the air in the fighting compartment. Changes to the fighting compartment have also been made to accommodate the cooling equipment for new THALES- Catherine-FC thermal imager. India plans to have 310 T-90S and 1,330 T-90M tanks in service by 2020.