Tuesday, March 20, 2012

AIM-120 problems blamed on humidity

An investigation blamed moisture for the cracking in the radomes of some US-made AIM-120s, but French and Taiwan-made missiles do not seem to be affected

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.

My article, published today in the Taipei Times, continues here.


Michael Fagan said...

"...despite being exposed to the same climatic conditions, storage and rotation cycles."

But is that right? The airforce has more F-16s than Mirages. The viper is the mainstay and so presumably it gets flown more frequently than the other aircraft. If that's true, then surely it would be plausible to suppose that the AIM120s it carries get exposed to more humidity (e.g. from flying through cloud cover) than the French missiles carried on the Mirages.

J. Michael Cole 寇謐將 said...

@Mike: The main problem here is prevailing ambient humidity, not flying through clouds (there is cloud cover the world over). Under this logic, exposure to Gs, rather than humidity, would be the main problem.

Your point could apply to the MICA on the Mirage-2000s, but bear in mind that the TC-II is on the IDFs, of which there are 130 — that's only 16 aircraft less than the F-16A/Bs.

Michael Fagan said...

You know... reluctant to attribute to malice what might be better explained by error. Or poor maintenance. Or poor build quality. Or some combination thereof.

Does the cracking problem occur on the older Sparrows too?

J. Michael Cole 寇謐將 said...

Oh don't get me wrong, I don't think this is malicious either (though some unnamed "analysts" cited by UDN claim this is a way for the US to "control" the Taiwanese military). It's probably poor built, mixed with poor maintenance and storage. But the fact that this is occurring only with the AIM-120s — which Taiwan paid a lot of money for — calls for a solution (not to mention their utility in air-to-air combat). I' ve not heard of this problem plaguing the AIM-7s and -9s.

Michael Fagan said...

Then it is a bit strange, as, assuming a correlation between age and use, you'd expect the cracking to occur on the older stuff first.

Oh and ... clouds the world over - I thought I remembered seeing them in Europe.