Methods and systems for detecting a structural failure of a fan blade of a fan rotor of an engine are described herein. A fan rotor speed and an engine vibration parameter are obtained. A rate of change of the fan rotor speed is compared to a deceleration threshold and the engine vibration measurement is compared to a vibration threshold. Structural failure of the fan blade is detected when the engine vibration measurement exceeds the vibration threshold for a period of time and the rate of change of the fan rotor speed is below the deceleration threshold. In response to detecting the structural failure, an alert indicative of the structural failure is triggered.