The Indian Army has initiated a long-pending major overhaul of its indigenous Arjun Mk-1 main battle tanks.
Six years after the first batch was scheduled for deep maintenance, a pilot project has commenced at the Heavy Vehicles Factory (HVF) in Avadi, Chennai, under the state-owned Armoured Vehicles Nigam Limited (AVNL).
Under this initiative, two tanks will be completely dismantled, refurbished, and modernised.
According to defence sources, these two pilot tanks will not merely undergo repairs but will also be equipped with 26 advanced features adopted from the latest Arjun Mk-1A variant.
The primary goal of this pilot phase is to establish standardised assembly procedures and repair manuals, which will eventually guide the overhaul of the remaining 124 Arjun Mk-1 tanks currently in service.
Since their initial induction starting in 2004, the Arjun tanks have never undergone a comprehensive overhaul.
A 2016 report by the Comptroller and Auditor General (CAG) highlighted that the first overhaul was due in 2020, but the responsible agency had not been finalised at the time.
A subsequent CAG audit noted that without dedicated repair facilities and adequate spare parts from HVF, many tanks had remained non-operational since 2013.
Despite the delay in a complete teardown, partial maintenance has continued in the background.
The Engine Factory Avadi (EFA) and the Combat Vehicles Research and Development Establishment (CVRDE) had previously conducted overhauls specifically on the tank's powerpack.
However, this new initiative marks the first time the hull and turret will be completely stripped and rebuilt.
One major challenge facing the current project is the lack of comprehensive technical documentation for such a complex rebuild.
Engineers at the factory will have to develop repair protocols dynamically by assessing the physical condition of individual components as the two tanks are disassembled on the shop floor.
Out of the 26 new upgrades being retrofitted, six are considered major capability enhancements.
These include a new commander’s panoramic sight for better battlefield surveillance, an Mk-II gunner’s main sight, an automatic target tracker, an upgraded muzzle reference system, redesigned tracks with increased horn height, and an advanced running gear system to drastically improve mobility.
The remaining 20 modifications focus on essential utility and safety improvements.
These range from a compact 8-kilowatt high-power auxiliary power unit (APU) and an advanced fire detection and suppression system, to LED headlights, periscope heating elements, and improved dust sealing for harsh desert operations.
The repair process involves a widespread defence supply chain.
Once taken apart, the primary diesel engine will be sent to Engine Factory Avadi, while the transmission and final drive will be handled by RENK's Indian subsidiary.
The 120mm rifled main gun and its cradle will go to Advanced Weapons and Equipment India Limited (AWEIL), and the gun control system will be overhauled by Bosch Rexroth in Germany.
Additionally, crucial components like batteries, gyros, tracks, and the panoramic sight will be sourced from domestic defence manufacturers.
Maintaining the Arjun Mk-1 fleet has been historically challenging due to a high reliance on foreign parts. A 2017 CAG report revealed that the tank had 69% imported content when it was first inducted.
Parts were sourced from various countries including Germany, Belgium, Israel, France, and the UK—some of which are no longer in business.
The report also pointed out that delays in indigenising components by the DRDO and a shortage of spares from HVF severely impacted the fleet's readiness.
The heart of the 58.5-tonne Arjun Mk-1 is a 1,400 horsepower MTU MB 838 Ka-501 V10 diesel engine from Germany, paired with a RENK transmission. This heavy-duty powerpack is designed to run for 600 hours or 5,000 kilometres before requiring a mandatory overhaul.
Logistics have also proven to be a hurdle for the heavy tank. Transporting the Arjun requires specialised broad-gauge railway wagons or heavy-duty road transporters, both of which are costly and limited in availability.
The 2017 audit noted that moving a single regiment of around 60 tanks requires at least 50 extra personnel and 16 additional transport vehicles.
After the complete rebuild, the two pilot tanks will face rigorous testing. This includes stand tests for the hull and turret, stability checks, and running trials.
Finally, they will undergo limited validation firing tests at the Pokhran ranges in Rajasthan. The refurbished tanks will come with a renewed warranty of 24 months or 150 engine hours, whichever occurs first.
In related developments, the Indian Army is still awaiting the delivery of 118 newly ordered Arjun Mk-1A tanks.
Procured from HVF in September 2021 under a ₹7,523 crore contract, this advanced 68-tonne variant is currently delayed primarily due to global supply chain issues regarding its German engines.
Meanwhile, the existing 124 Mk-1 tanks continue to serve in the 43 and 75 Armoured Regiments, guarding the critical desert sectors of Rajasthan.
