The grounding of Dhruv advanced light helicopter (ALH) is expected to continue for another three months, as the defect investigation committee (DIC), set up to find out what caused the fatal crash of a Coast Guard ALH in Porbandar of Gujarat on January 5, is yet to determine the cause of the accident.
Three people—pilots and an aircrew diver—onboard had died in the crash, forcing the authorities to ground around 330 ALHs operated by the Indian Army, Navy, Air Force and Coast Guard.
While the panel found that the accident was caused by a fracture in the swashplate—a critical mechanical device used in helicopters to translate pilot or autopilot flight control inputs into motion for the main rotor blades—it is not yet known how the breakdown happened, say media reports.
In the wake of the crash, an inspection was conducted across the fleet of the three services and the Coast Guard, which led to the discovery that a few more jets were facing the same problem.
Hindustan Times quoted some sources as saying that this fracture could be caused by constant exposure to saline environment as the issue was found with Navy and Coast Guard jets.
Meanwhile, ALH developer Hindustan Aeronautics Limited (HAL) has roped in the Bengaluru-based Indian Institute of Science (IISc) to assist with the ongoing investigation to conduct fatigue testing of a critical part in the aircraft's transmission system to find out the exact cause of the fracture.
According to officials, HAL has given the raw material with which the swashplate is made to IISc to carry out tests to see how the material withstands loads in different conditions.
"Once that report is in, we will know whether it was a material failure or something else,” an official has been quoted as saying.
IISc is likely to submit its report to DIC by the end of April and the latter will incorporate the findings in its report which is expected to come in May. "It will take at least another month to carry out fleet-wide checks and fix the problem. How fast the ALH fleet can return to service will also depend on whether the checks can be carried out on the field or the integrated dynamic system, including the transmission system, gearbox and rotor hub, of each helicopter will have to be brought to HAL,” Hindustan Times quoted an official as saying.
There is also the likelihood of the fleet being out of action for more than three months if the issue happens to be with the design, according to an official.
