NEW DELHI, Aug. 14 -- Plane maker Hindustan Aeronautics Limited (HAL) has carried out extensive tests on the Dhruv advanced light helicopters in a maritime setting in an attempt to pinpoint and fix a lingering flaw in helicopters operated by the navy and coast guard that have been grounded for more than seven months following a fatal crash in Gujarat, officials aware of the matter said on Wednesday. The tests, carried out off the Visakhapatnam coast for two weeks, saw the ALH operate from warships in different weather conditions, the officials said, asking not to be named. "HAL has collected a lot of data during these trials. The data is being analysed at the Rotary Wing Research & Design Centre and the findings will be submitted to the defect investigation committee (DIC) by August-end," said one of the officials cited above. The military's 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 ALH's --- 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. 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 DIC. The problem with the navy and coast guard appears to be linked to sustained operations in a maritime environment, as previously reported by HT. "HAL is trying to determine the exact problem and fix it. The DIC will scrutinise the data compiled by the Rotary Wing Research & Design Centre and recommend the next steps," said a second official. 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 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's motion 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, 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....