The Taiwan Air Force has had a unique problem with their older (three years or more) AMRAAM air-to-air missiles. The radomes (protecting the radar) on the front of the missile have developed cracks. This appears to be caused by prolonged exposure to the hot and moist climate in Taiwan. Over time the moisture and heat cause the radome material to degrade. The U.S. manufacturer advised Taiwan to store the missiles in drier and cooler conditions, which should eliminate the problem.
The latest version of AMRAAM is the AIM-120D. The older, AIM-120C7 version is mostly used by foreign customers. Since it entered service two decades ago over 40 air forces have bought AMRAAM. Most of these missiles are never fired in combat, training, or tests and are removed from service after a decade or more of service and several rounds of upgrades and refurbishment. The missiles spend some of their time mounted on aircraft but mostly they are in storage.
AMRAAM entered service in 1992, more than 30 years after the first radar guided air-to-air missile (the AIM-7 Sparrow). AMRAAM was meant to succeed where the AIM-7 didn’t. Vietnam, in the 1960s, provided ample evidence that AIM-7 wasn't really ready for prime time. Too many things could go wrong. Several versions later, the AIM-7 got another combat test during the 1991 Gulf War. In combat 88 AIM 7s were launched, with 28 percent scoring a hit. The AIM 9 Sidewinder did worse, with 97 fired and only 12.6 percent making contact. That said, most of these hits could not have been obtained with cannon, especially when the AIM 7 was used against a target that was trying to get away.
AMRAAM was designed to fix all the reliability and ease-of-use problems that cursed the AIM-7. But AMRAAM has only had a few opportunities to be used in combat, and over half of those launched have hit something. The 120D version entered service four years ago and has longer range and greater accuracy and resistance to countermeasures. So far, AMRAAMs have spent nearly two million hours hanging from the wings of jet fighters in flight. Some 2,400 AMRAAMs have been fired, mostly in training or testing operations. That’s about a quarter of those produced.
AMRAAM weighs 172 kg (335 pounds), is 3.7 meters (12 feet) long, and 178mm (7 inches) in diameter. AMRAAM has a max range of 70 kilometers. These missiles cost about a million dollars each. The missiles are complex mechanical, electronic, and chemical systems and each of them, on average, suffers a component failure every 1,500 hours.