A fan blade separated from the right engine of United Airlines Flight 1175 before the engine cover broke off, forcing the jet to make an emergency landing in Honolulu on Feb. 13, according to a preliminary investigation released Tuesday.

The National Transportation Safety Board found that the fan blade on the Boeing 777 separated at about noon, shortly after the flight’s initial descent from an altitude of about 32,700 feet, followed by the “subsequent loss of the inlet and fan cowls” of the engine, a Pratt & Whitney PW4077.

The flight was en route from San Francisco to Honolulu.

After receiving warnings of an engine compressor stall, the flight crew shut down the engine, declared an emergency and proceeded to safely make an emergency landing at Daniel K. Inouye International Airport. No injuries were reported to the 363 passengers and 10 crew members aboard.

The NTSB is expected to release a full report in coming months following the completion of its investigation