Trojan1981, the accident was caused by a combination of three factors,
namely, pilot induced overload in that the pilot exceeded the aircraft’s
operational limit of 3 g, manufacturing deficiency in that several wing leading
edge ribs were below the specified thickness, and under the conditions of the
accident, the onset of transonic compressibility effects that increased the
aerodynamic loads on the leading edges beyond the level that the sub - standard ribs could bear.
Notably, the ribs as designed had a failure point of 3.9 g and the below specification ribs had a failure point of 3.4 g. During the aircrafts design no allowance had been made for transonic compressibility effects. It was the compressibility effects that lead to the rib overload. Its ironic that a US Navy P-3 also had an identical LE failure (also at Cocos, must be some thing in the water there) 3 years previously, but landed safely. An opportunity lost to nail the problem?
Full report here
http://dspace.dsto.defence.gov.au/ds...-0008%20PR.pdf