HAL, Indian Army Probe Dhruv Helicopter Tail Drive Shaft Defect Amid Safety Concerns

HAL and the Indian Army launch a joint investigation into a critical tail drive shaft defect in the Dhruv ALH, prompting a fleet-wide safety check.

BENGALURU – Hindustan Aeronautics Limited (HAL), India's state-run aerospace and defense giant, on Sunday emphasized the critical role of preventive maintenance in ensuring the continued airworthiness of its Dhruv Advanced Light Helicopter (ALH) fleet. The announcement comes in the wake of a newly reported technical defect involving the aircraft’s tail drive shaft (TDS)—a core component that transmits power to the tail rotor and is integral to flight stability.

The statement followed a report by Hindustan Times on Saturday that revealed a fresh safety directive issued by the Indian Army after a TDS bearing mount broke mid-flight on September 4. The incident prompted immediate orders for a fleet-wide, one-time safety check across all ALH units, including those operated by the Indian Navy and Air Force.

Routine Check, Serious Implications

In a carefully worded response, HAL clarified that the One-Time Check (OTC) is a standard operating procedure initiated following any major defect. The company also confirmed that it had dispatched expert technical teams to support the Indian Army in conducting a root cause analysis.

“HAL reiterates that maintenance aspects are critical to the continued airworthiness of helicopters and emphasises that all maintenance directives must be followed scrupulously,” the official statement said.

However, the gravity of the defect cannot be understated. The tail drive shaft is essential in stabilizing the aircraft during flight by counteracting the torque generated by the main rotor. Any malfunction in this area risks compromising the directional control and safety of the helicopter, especially during complex operations such as high-altitude flying or maritime missions.

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A Legacy Under Scrutiny

First inducted over two decades ago, the ALH has become a vital asset in India's rotary-wing operations. With over 450,000 flying hours logged, and a fleet of around 330 aircraft in service across the Army, Air Force, Navy, Coast Guard, and civil sectors, the ALH has built a legacy of versatility—from search and rescue missions in the Himalayas to flood relief in coastal states.

Yet, safety concerns have plagued the program in recent years. The helicopter has been involved in at least 15 accidents in the past five years, prompting multiple fleet-wide groundings and technical reviews.

Most recently, a fatal crash of a Coast Guard ALH in Porbandar on January 5, 2025, led to the grounding of several variants, particularly those operated in maritime environments. That accident was attributed to a swashplate fracture, though investigators have yet to conclusively determine what caused the component failure.

In the aftermath, the Army and Air Force ALH variants were declared airworthy again on May 1, following exhaustive evaluations by a defect investigation committee comprising officials from HAL, the Centre for Military Airworthiness and Certification (CEMILAC), and the Directorate General of Aeronautical Quality Assurance (DGAQA).

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A Complex Web of Technical Challenges

The latest TDS-related issue adds to a growing list of concerns around the mechanical resilience and structural integrity of the ALH platform. Though HAL has undertaken design revisions and upgraded control systems in 2023-24, these efforts appear to be falling short of fully addressing the root issues.

Sources suggest the upcoming investigation will explore multiple angles, including the durability of components under operational stress, particularly in maritime and high-altitude conditions, as well as the strictness of adherence to scheduled maintenance routines by end-users.

Notably, helicopters operated by the Navy and Coast Guard have remained grounded for more than eight months following the Porbandar crash. HAL has since conducted extensive testing in simulated maritime environments to identify persistent flaws unique to salt-laden, humid operational zones.

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The Way Forward

As the root cause investigation unfolds, HAL’s statement signals a renewed focus on collaborative diagnostics and proactive maintenance. The company’s continued involvement in fleet support and upgrades suggests that authorities are not yet considering a broader phase-out of the ALH platform.

Industry experts caution, however, that unless systemic reliability and predictive maintenance are strengthened, India's ambitions for indigenous helicopter manufacturing could suffer setbacks—not just in domestic operations but also in export potential.

Meanwhile, the Indian Army’s operational tempo remains high, especially in the wake of ongoing flood rescue and evacuation missions. Despite recent issues, ALHs continue to be deployed in life-saving roles, underscoring both their importance and the urgency of resolving current technical deficiencies.

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Editorial Note:
The Dhruv ALH remains a cornerstone of India’s indigenous defense manufacturing capability. But with safety incidents mounting and components under increasing scrutiny, the onus now lies on HAL and the armed forces to ensure that robust, timely, and transparent measures are taken—not only to restore trust in the platform but to protect the lives of those who fly them.