New Delhi, Feb. 27 -- The chartered patient transport flight that crashed near Ranchi while flying to Delhi on February 23 was a 39-year-old plane unused for at least four years until 2022, officials aware of the details said, declining to be named. The plane's history of operations, maintenance, and ownership, along with weather, are among the main areas of investigation into why the twin-seater Beechcraft C90A (King Air) plane crashed, claiming the lives of all seven on board. The plane, two of these officials said, was practically unused until 2022 when its current owners, Redbird Aviation, bought it from Orient Flying School. "The aircraft flew in Chennai in its initial days. It was later moved to Puducherry as the flying school that owned it had a base there. However, it was subsequently shifted to Mysore, where it was completely grounded," one of the officials said. The other official said: "It is not known to have flown actively after moving out of Chennai." Investigators are expected to take a wide approach to the probe, especially since the aircraft was not equipped with a black box (cockpit voice and flight data recorders) because it weighed less than the minimum threshold requiring such devices. In all, it had raked up 6,600 hours in what is known as airframe hours. Experts said the number appeared low for a plane manufactured 39 years ago. The Beechcraft C90A (King Air) twin-turboprop was registered as VT-AJV and manufactured in 1987. It was bought by Orient Flying School in 2001 and sold to Redbird Aviation in 2022, two years after the airline commenced operations. Before being purchased by an Indian operator, the plane had three American owners between December 1990 and June 2001. It was originally bought from Beechcraft, the manufacturer, by a Brazilian company. A former Directorate General of Civil Aviation (DGCA) official said maintaining an ageing, inactive aircraft requires unnecessary investment just to keep its airworthiness certificate current. "Maintenance of an ageing aircraft that is not actively flying or is grounded is a loss to any company as it has to keep its airworthiness certificate current for it to be able to sell their non-performing asset," he said. When asked whether an ageing aircraft was a concern for operators, experts said age alone was not a safety issue. "The age of the aircraft doesn't matter as long as it is well maintained," an industry insider said. Another person said operators typically continue using aircraft unless they require frequent replacement of spare parts or when the manufacturing of an aircraft has long been discontinued. "As the aircraft ages, it becomes essential to ensure its structural integrity and detect cracks and corrosion in time. Various non-destructive tests are conducted to certify that the machine is airworthy. A few of these checks, like X-ray inspections, are expensive but, if undertaken in right earnest, enhance safety [and] can help avoid catastrophe," said a former director general of the Aircraft Accident Investigation Bureau of India (AAIB). Mark Martin, founder of Martin Consultancy, questioned the aircraft's flying hours. "I believe the crashed C90 has had three owners since new. 6,600 flying hours is low, about 150 hours a year. But if the aircraft was not grounded, 6,600 hours for a 39-year-old aircraft prima facie appears extremely low, almost an unbelievable number for such an old aircraft. Under-logging of flight hours seems likely; it is rampant in the industry and is often done to delay scheduled maintenance. The DGCA is aware of this practice, and stricter rules should be implemented, including financial penalties or suspension of the air operator certificate," he said. When asked about the wreckage, a ministry official said, "The team is at the spot collecting spare parts scattered after the aircraft crashed on Monday evening. A few of them have been found as far as one kilometre from the crash site. Analysis of the wreckage will follow." "The audit of Redbird Aviation was conducted (as part of special audits launched this month) recently and nothing alarming was found," he said, adding that the airworthiness review certificate of the aircraft was extended for the year only on January 21 after checking the aircraft, which was deemed fit to fly. "During the transfer of ownership too, an extensive check was conducted after which it was made to be used by Redbird," the official said....