Line Replaceable Unit

A Line Replaceable Unit is a modular component and is usually sealed unit of an aircraft, which is designed to be replaced within a short time without using very specialized tools. This means that the aircraft can quickly return to service, while the failed LRU is being tested and repaired. It is a component which can be readily changed on an aircraft during line maintenance operations. Line Replaceable Unit is a major control or accessory that is mounted on the external portion of an Engine.