Engines of a TransAsia plane that crashed into a river in Taipei killing at least 35 people failed to produce enough thrust to the propellers two minutes after take-off, Taiwanese aviation authorities said.
Flight GE235 was carrying 58 passengers and crew when it lurched nose-up between buildings, clipped an overpass and a taxi with one of its wings and then crashed upside down into a shallow river on Wednesday.
Fifteen people survived and eight are still missing.
The black box data and voice recorders of the two-engined aircraft showed that problems with the right engine were followed by problems with the left and the plane warned five times of stalling before the crash in the centre of Taipei, Aviation Safety Council officials told a news briefing on Friday.
The right engine first entered a state called "auto-feather", in which it reduced thrust to the propeller, Thomas Wang, managing director of the council, said.
The flight crew then reduced acceleration on the left engine and then attempted to restart it, but it did not gain enough thrust. He did not give a reason for the engine failure.
"The first engine experienced a problem 37 seconds after take-off at 1,200 feet," Wang said.
The official said the pilot had announced a "flameout", which can occur when fuel supply to an engine is interrupted or when there is faulty combustion, but there had not been one.
"The flight crew stepped on the accelerator of engine 2 [right hand side] ... The engine was still operating, but neither engine produced power."
He said the aircraft could fly with one engine. The plane was powered by two Pratt & Whitney PW127M engines. Pratt & Whitney is part of United Technologies.
The pilot, hailed as a hero for his actions in the final moments, was still holding the joystick in the cockpit when his body was found, media reported on Friday.
The pilot, 42-year-old Liao Chien-tsung, has been praised by Taipei's mayor for steering the plane between apartment blocks and commercial buildings before ditching the stalled aircraft in a river.
Taiwan's aviation regulator has ordered TransAsia and Uni Air, a subsidiary of EVA Airways Corp, to conduct engine and fuel system checks on the remaining 22 ATR aircraft they still operate.