A method of drive system diagnostics of an aircraft includes capturing high load drivetrain component vibration data at select steady-state and/or high-load transient operating conditions of the aircraft and processing the captured vibration data to improve reliability and/or accuracy of the captured vibration data. The processed vibration data is utilized to provide a health assessment of the drivetrain components and achieve earlier detection of incipient faults. A health monitoring system for drivetrain components of an aircraft includes a plurality of vibration sensors positioned at drivetrain components of an aircraft to capture drivetrain component vibration data at transient operating conditions of the aircraft. One or more processing modules process the captured vibration data to improve reliability and/or accuracy of the captured data, and a fault reasoning module calculates a health indicator of the drivetrain components.