An investigation has concluded that cracking occurring in the radome on some of the US-made AIM-120C air-to-air missiles carried by Taiwan’s F-16s was caused by long-term exposure to humidity and stress, the Air Force General Headquarters said yesterday.
The air force made the comments after local media reported earlier the same day that the problem with the missile — the most advanced in the Taiwanese air force — had been observed for three consecutive years.
The air force currently has 120 AIM-120C-5 and 218 AIM-120C-7 advanced medium-range air-to-air missiles (AMRAAM) in its inventory.
The “fire-and-forget” missiles are used on its 146 F-16 aircraft. The first order of AIM-120s was delivered to the air force in 2004.
Radomes, one of the eight main sections of a missile, are a pyroceramic cone at the nose that serve as a window for radar or heat-seeking electromagnetic devices inside the missile.
In a statement, the air force said it had followed US suggestions to improve rotation cycles and store the missiles in conditions that would reduce the impact of moisture on the radomes.
The US has been asked to repair the damaged missiles, the statement said, adding that the problem had not undermined national defense.
Raytheon Corp is the main manufacturer of the missile.
In a report on the 2010 AMRAAM International Users’ Conference held in Florida in May 2010, the Taiwanese air force had already identified the problem and said it had sought the assistance of the US in addressing the impact of high humidity on the missile.
The US investigation into the causes of the cracking has ruled out accidental damage caused by poor packaging or handling, as well as vandalism. The probe concluded that the high humidity in Taiwan, as well as the tremendous pressure exerted on the missiles from supersonic flight, were the principal causes of the problem.
However, the radomes on the French-made MICA and the domestically produced Tien Chien II “Sky Sword” — two other air-to-air missiles used by the Taiwanese air force — do not seem to have had similar problems, despite being exposed to the same climatic conditions, storage and rotation cycles.
According to information on Raytheon’s Web site, 36 countries worldwide have procured the AIM-120. The missile is also used on US aircraft carrier-based F/A-18 Hornet aircraft.
With translation by Jake Chung, Staff writer