The UK Royal Navy's light aircraft carrier HMS Illustrious is to undergo a £40m ($63.8m) upgrade at Rosyth Dockyard in Fife.
The maintenance and upgrade programme will include replacing 500m of pipework, 650 valves and all eight exhausts, as well as making the ship more fuel-efficient.
HMS Illustrious is the second of the three Royal Navy's Invincible Class light aircraft carriers, and has participated in most major UK and Nato campaigns since its commissioning in 1982.
In 2003, the ship underwent a £118m ($188.2m) refit at Rosyth.
The present upgrade contract is part of a continuous programme of work at Rosyth before assembly work begins for the Royal Navy's two new super carriers.