A preliminary investigation by India’s aviation regulatory agency of an Oct. 12 incident involving an Air India Boeing 787 indicates that a riveting flaw in the panel covering the heat exchanger unit could have caused the panel to detach from the fuselage.

The 8 ft. X 4 ft. panel Bengaluru International Airport fell from the underside of the jet and landed within the perimeter of Bengaluru International Airport, an Air India official says, noting that “the panel has since been fixed and the aircraft is in operation again.”

Boeing says that the loss of the panel would not have posed safety risks to passengers. The aircraft was carrying 148 passengers and crew on a flight from Indira Gandhi International Airport in New Delhi to Bengaluru International Airport.

“It was the mid-underwing-to-body fairing located on the belly of the airplane on the right side,” says Boeing. The part “provides a more aerodynamic surface in flight.”

Boeing is working to find out what caused the panel to detach.