ALH Dhruv: HAL Shifts To Steel Control Rods After String Of Crashes, Safety Review

After the recent spate of crashes that grounded the entire fleet of advanced light helicopter (ALH) Dhruv, the Hindustan Aeronautics Limited (HAL) has decided to change its aluminium-made control rods to steel-made control rods.

Concerns about the ALH Dhruv's safety were heightened when three crashes occurred within a span of two months.

As a result, the entire Dhruv fleet was grounded, and a 'critical design review' was started by Centre of Military Airworthiness and Certification (CEMILAC), a safety regulator, functioning under DRDO.

Two months ago (on 8 March), a Navy ALH Dhruv has ditched in the Arabian sea due to a sudden loss of power. Another, Coast Guard Dhruv crashed two weeks later on 26 March, at the Cochin International Airport.

Early this month (4 May), an additional Dhruv belonging to army, made another forced landing in Kishtwar region of Jammu and Kashmir.

Reportedly, all three helicopters crashed due to a failure of control rods. "In the first case, the crash happened due to improper fitment of washers and in the second case, two similar control rods were interchanged at the time of maintenance," which resulted in the failure of controls leading to sudden loss of power.

Steel rods will be easier for maintenance, the officials added.

To address the concerns raised, CEMILAC has initiated a design review based on the earlier report from the expert committee created after the first two crashes which explored reasons for the failure of control rods.

The report highlighted the drastic reduction in the fatigue life of the aluminium rods, happening due to an assembly error of serrated washers in the booster control rods.

“The drastic reduction in the fatigue life of the control rod with wrongly assembled serrated washers has been verified experimentally at Rotary Wing Research and Design Centre (RWR&DC), HAL as part of the committee’s investigation,” CEMILAC has then stated in the letter addressed to all the services.

In addition to grounding the ALH Dhruv, the forces have also grounded the light combat helicopter (LCH) in service with the army and the air force, which also uses parts from the ALH.

With the introduction of these steel rods, the HAL hopes that these accidents will become a thing of the past.