Ahmedabad Air India tragedy: Why USA's Federal Aviation Administration and NTSB surveying crash site?

Members of the US-based National Transportation Safety Board (NTSB) and Federal Aviation Administration (FAA) on Sunday surveyed the site of the Air India plane crash that killed at least 271 people in Ahmedabad.
The Boeing 787-8 Dreamliner, with 242 people on board and bound for London's Gatwick Airport, hit residential buildings located not far from the runway and crashed seconds after takeoff on Thursday. All but one passenger on board were declared dead in what was described as the world's worst aviation disaster in a decade. The casualties included around 30 people on the ground who were inside the buildings the aircraft rammed into.
There were no immediate comments from the FAA or NTSB at the time of compiling this report. Air India and the Centre looked into several aspects of the crash, including issues linked to engine thrust, flaps, and why the landing gear remained open as the plane took off and then came down.
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According to news agency Reuters, the Secretary of the U.S. Department of Transportation, Sean Duffy, on Friday said he was in the process of deploying a team from the FAA and the NTSB to New Delhi. Boeing and GE, whose engines were used in the plane, also sent teams. "We’ll take action should any recommendations come forward from the NTSB’s investigation," Duffy said.
In the U.S., the Federal Aviation Administration oversaw aspects of civil aviation, including safety regulations, pilot licensing, aircraft certifications, and air traffic control. The National Transportation Safety Board, meanwhile, was an independent federal agency responsible for investigating accidents involving various means of transport.
The FAA said India would lead the investigation, but the NTSB was the official U.S. representative for providing assistance, while the FAA provided technical support. Boeing officials also looked at various parameters in their inspections, including the angle of landing, as they investigated the matter, said the first source. In total, around 10 officials were present at the site on Sunday, including those from the NTSB, said the second source.
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The Centre on Saturday set up a high-level multi-disciplinary panel to ascertain the "root cause" of the plane crash and assess any contributing factors, including mechanical failure, human error, and regulatory compliance. The panel, headed by Union Home Secretary Govind Mohan, was mandated to submit its report in three months. As many as 230 teams were formed to coordinate with the victims' families, officials earlier said.
India's aviation regulator ordered all Boeing 787s operated by local carriers to be inspected. The crash posed a fresh challenge for both Air India, which had been trying for years to revamp its fleet, and Boeing, which was trying to rebuild public trust following a series of safety and production crises.
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In Ahmedabad, doctors struggled to identify bodies that were charred in the incident, resorting to dental samples and DNA profiling. DNA samples of 32 victims from the crash were successfully matched, Rajnish Patel, Additional Superintendent at the city's main hospital, said on Sunday. "The bodies for which DNA samples were matched are being handed over to the families with due respect," he said.
India