Sunday, February 27, 2005

Hercules Mystery Bubbles Away

Back on Monday, 7th February I blogged on the suggestion that a jury-rigged SA-4 might have been responsible for the destruction of the RAF C-130K on election day in Iraq. We went into some detail about the SA-4 system and flagged the secondary optical guidance as a possible candidate. We can now say with confidence that this possibility was taken seriously enough by the powers-that-be that Russian experts, either from the manufacturer or from the Russian air defence forces, were summoned to take part in the accident investigation. Apparently they concluded that the aircraft had not been hit by such a rocket, but also that its use was a distinct possibility and that the insurgent video distributed after the incident might show a genuine launch.

Since then, the US Air Force has grounded its fleet of E-model Hercules (the oldest in service) for urgent investigation of possible fatigue cracking in the central wing section. The Ministry of Defence, however, has so far been at pains to deny that this might affect British aircraft, claiming that ours are "different". The RAF operates two types of C-130 aircraft with two subtypes in each. The first are usually termed C-130Ks, but they are not equivalent to the US "K model". The "K" in this case is a purely British designation not used by Lockheed-Martin - it refers to the fitment of British avionics and more powerful engines to a C-130E airframe (such beasts are known in the US as Super Es). The structure is the same. The same went for all the Hercules delivered to the Royal Australian, Canadian and New Zealand Air Forces at the same time. The others, for completeness, are new C-130Js - in this case the terminology is not anomalous, their structural integrity is unquestioned, and we can happily forget about them and save confusion. All post-1975 Hercules have either a new wing introduced that year or another introduced in 1983, fabricated from a different alloy.

But MOD press spokesmen have stated to several media organisations, including the Times, PA News and the Evening Standard, that the British aircraft were "different", "completely different", "built differently" and "used for strategic flying" - none of which is true. Strangely, early in the investigation, those same nameless spokesmen were happy for the readers of the Sun to see the headline "THE WING CAME OFF" over their breakfasts: was this leaked because they were still concerned that the aircraft had been shot down at the time, and wanted to give the impression of an accident? Now, though, they seem keen to deny the possibility of - an accident.

At the same time as the RAF, the South African Air Force also received C-130s shortly before the US cut off military aid to South Africa. They therefore received no manufacturer support until the 90s. The South Africans have now grounded seven out of nine aircraft all with the same wing.

The other distinction is between short-body and long-body aircraft. This distinction is important as the RAF only uses the "short" aircraft for the most demanding tactical flying. In British official terminology, the "short K" is a Hercules CMk1 and the long K a Hercules CMk3. This should tell us something at once; unsurprisingly the Mk. 1 is the first to enter British service in 1967 and hence the oldest. Now, the K's are used for the mass of the RAF's tactical transport - dropping parachutists and loads, flying in and out of very restricted airstrips, navigating at low level in darkness - and the Mk.1s for the heaviest of the lot, supporting British special forces. Only five of them exist, and hence they are worked hard. And they share a structure with the USAF C-130Es - so why has the MOD not taken the same precaution?

However, there are still further questions; the aircraft (XV179) that crashed in the rebel-haunted desert north of Baghdad had been modified in 2002 with the installation of a new, stronger outer wing section. So surely the problem doesn't apply? Or did the fix shift the strain elsewhere? Or possibly hostile action really did play a part? The Special Forces support aircraft of 47 Squadron (one of which 179 was) are said to have often been overloaded for operational purposes, including operations Bleed and Dbamien in Afghanistan during the winter of 2001/2.


HappyClam said...

Secondary optical guidance on SA-4 battery employed against C-130 in Iraq in January?


That's just not a very reasonable hypothesis, although it is creative.

You're likely on to something much more relevant with the discussion of the previous overloading of XV179 and the various modifications made over the years.

Anonymous said...

See mi_m0UBT/is_7_19/ai_n10020756/pg_3 - 22k
The wing fell off. Manpads ceiling is 15000 ft.

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