Engines No. 3 and [No.] 4 were dredged from the lake located below the aircraft's flight path, together with the engine pylons and many parts of their nose cowls and thrust reversers," the report said. "Internal rub marks and other witness marks indicated that when the engines hit the water they were either at a low rotating speed or had stopped. Internal examination of engine [No.] 3 and [No.] 4 showed no abnormal signs of pre-existing damage.