The fleet of indigenous Advanced Light Helicopters (ALH) has started flying operations again, nearly a month after two successive crashes of coast guard and naval variants of the aircraft. Extensive checks on the entire fleet of helicopters, also in service with the Army and Air Force, were undertaken and no signs of any deep-rooted issue with the aircraft were found.It is learnt that both accidents that took place in March were related to a control failure. No aircrew had suffered fatal casualties and the helicopters could be recovered fully to study the reasons behind the technical faults. The initial probe has found that the reasons behind the failure were maintenance related.In one case, the fault appears to have occurred due to the improper fitment of washers, while in the other, two similar rods were interchanged during the maintenance process. Following the crashes, the entire fleet was assessed by technical teams and no red flags have been raised after thorough checks. Additional training is being given to crews to ensure such issues do not come up again.A workhorse for the armed forces that operates in diverse environments from warships to high altitude areas like the Siachen glacier, the ALH fleet has undertaken over 3.9 lakh flying hours till now. The armed forces, as well as some export customers, are flying 338 helicopters of the type, with orders for several dozen more in the pipelines.Internal records seen by ET show that the accident rate has sharply declined in the past five years. The average rate since 2018 has been 5.5 accidents per one lakh flying hours. Prior to 2018, this rate was 9.5 per lakh flying hours.