The U.S. Navy is buying (for about $4 million each) another 82 F-414-GE-400 engines for its F-18E fighters. The engines weigh 1.1 ton and are 3.9 meters long and 89cm in diameter. Each F-18E has two of them, with each one generating ten tons of thrust. Most of these aircraft will go through several engines over its lifetime (at least 8,000 flight hours). The F-414 is good for 4,000 hours, although some components have to be replaced sooner (a few hundred to 2,000 hours). Thus an F-18E is likely to have an engine removed, or subject to extensive maintenance, several times a year.
There was a time (World War II) when the engine was the most expensive component of a warplane, but that has changed over the last few decades. The electronics are now the most expensive item, although with stealth aircraft, the airframe is.