Hyderabad, Feb. 1 -- Plane maker Hindustan Aeronautics Limited has fixed a nagging flaw afflicting a key component of the transmission system of the navy and coast guard's Dhruv advanced light helicopters and they are likely to be cleared to fly again in April, ending the longest grounding of an aircraft in the Indian military, HAL chief DK Sunil said on Saturday. The workhorse twin-engine fleet was grounded in January 2025 following a fatal coast guard crash. "HAL has started upgrading the swashplate assembly mounted around the Dhruv ALH's main rotor mast to boost its fatigue tolerance in a harsh marine environment, and the exercise will be completed by March-end. The swashplate assembly life has been significantly improved through refined manufacturing techniques," Sunil said at Wings India 2026, the four-day civil aviation show that ended at Begumpet airport in Hyderabad on Saturday. Any defect in the swashplate assembly can compromise the ability of the pilots to control the helicopter's motion -- it translates stationary control inputs from the pilot into rotating inputs connected to the main rotor blades. The snag related to the swashplate assembly in the navy and coast guard helicopters was detected after the fatal coast guard ALH crash at Porbandar in Gujarat on January 5, 2025 in which two pilots and an aircrew driver were killed. The military's entire fleet of 330 ALHs was instantly grounded. Four months later, on May 1, the 300 choppers operated by the army and air force were declared airworthy by HAL after comprehensive safety checks. The 30 ALHs operated by the navy and coast guard were, however, not given the green light to return to the skies. A fleet-wide inspection conducted after the January 5 crash revealed that the navy and coast guard ALHs were facing the same problem as the Dhruv that crashed in Porbandar -- cracks in the swashplate assembly, linked to sustained operations in a saline environment. HT was the first to report on February 4, 2025, that a detailed analysis by the Council of Scientific and Industrial Research-National Aerospace Laboratories, Bengaluru, pointed to a swashplate assembly failure. htc...