Fix eludes HAL on navy, coast guard Dhruvs
The military’s advanced light helicopter (ALH) fleet was grounded following a fatal coast guard crash at Porbandar in Gujarat on January 5
NEW DELHI: Plane maker Hindustan Aeronautics Limited (HAL) is struggling to pinpoint and fix a lingering flaw in the Dhruv advanced light helicopters operated by the navy and coast guard, and a question mark hangs over when will the locally produced choppers --- grounded for almost six months now --- return to service, officials aware of the matter said on Wednesday.
The military’s advanced light helicopter (ALH) fleet was grounded following a fatal coast guard crash at Porbandar in Gujarat on January 5, but the army and air force choppers were declared airworthy after comprehensive safety checks on May 1.
HAL has instrumented two ALHs --- one each from the navy and coast guard --- to gather critical data on the performance of the helicopter’s integrated dynamic system, including the transmission system, gearbox and rotor hub, as well as test the loads some systems can withstand in different operating conditions, said one of the officials cited above, who asked not to be named.
“The data will be thoroughly analysed to determine the root cause of the problem that appears to be linked to sustained operations in a saline environment. There are no issues with the army and air force ALHs,” the official said. The navy and the coast guard together operate around 30 ALHs, designed and developed by HAL.
The 300 ALHs operated by the army and air force were cleared for flying duties based on the recommendations of the defect investigation committee (DIC).
The data obtained from the two instrumented helicopters (fitted with gauges and sensors) will be compiled and analysed by July-end, said a second official, who also asked not to be named. “That should help us identify the snag and fix it. HAL will then go back to the DIC with its findings to figure out the next steps,” he added.
The DIC consists of officials from the Bengaluru-based Centre for Military Airworthiness and Certification (CEMILAC), the Directorate General of Aeronautical Quality Assurance and HAL.
HAL had earlier broadened the scope of the investigation by involving Bengaluru-based Indian Institute of Science (IISc) to perform fatigue testing of a critical part (swashplate) in the helicopter’s transmission system to get to the bottom of the matter. This was after a high-powered panel found that a swashplate fracture caused the January 5 coast guard ALH crash in which two pilots and an aircrew diver were killed. But the reason for the breakdown of the critical component that compromised the ability of the pilots to control the helicopter could not be determined.
A fleet-wide inspection conducted after the January 5 crash revealed that some navy and coast guard ALHs were facing the same problem --- cracks in the swashplate assembly.
HT was the first to report that a detailed analysis by the Council of Scientific and Industrial Research-National Aerospace Laboratories (CSIR-NAL), Bengaluru, pointed to a swashplate assembly failure.
The ALH underwent a design review followed by a replacement of a defective control system only in 2023-24. The helicopter has been involved in around 15 accidents during the last five years, putting its safety record in the spotlight.
The coast guard suspended ALH operations following an accident last September when a helicopter crashed into the Arabian Sea near Porbandar. Then too, two pilots and an aircrew diver were killed. The grounding was for a one-time check; the three services did not ground their fleets then. The coast guard cleared the helicopters for flying a few weeks later, after a safety inspection involving HAL, CEMILAC and all coast guard units.
Last September’s accident, too, came after the design review that culminated in a critical safety upgrade on the ALH fleet. It involved installing upgraded control systems on the helicopters to improve their airworthiness. The comprehensive design review came after the ALH fleet was grounded several times in 2023 too after a raft of accidents called into question its flight safety record.
