This chapter provides a comprehensive study about the aircraft engine condition monitoring for predictive maintenance. Aircraft engines are among the most critical components of an aircraft, and their reliable performance is paramount to flight safety and operational efficiency. To ensure the continued airworthiness of these engines, maintenance practices have evolved from reactive to proactive approaches, with predictive maintenance emerging as a crucial strategy. This chapter explores the concept of aircraft engine condition monitoring for predictive maintenance, covering the key principles, technologies, methodologies, challenges, and benefits associated with this approach. It also provides aircraft noise and vibration measurement principle and its suppression technique. Aircraft condition monitoring using noise and vibration signals is a proactive approach to maintenance that enables early detection of faults, reduces downtime, enhances safety, and optimizes the operational efficiency of aircraft systems.