MAJOR deformities in the steel crankshaft of Whyalla Airlines Flight 904 did not exist when the plane crashed, an inquest into the tragedy was told yesterday.
Earlier this month, Coroner Wayne Chivell heard evidence from the University of Adelaide's Dr. Graham Powell, who used acids and microscopes to examine a piece of the crankshaft that broke inside the plane's left engine.
He said the shaft was riddled with "massive defects" called oxide inclusions – tiny abnormalities that occur naturally during steelmaking, but can lead to metal fatigue and fracturing.
International standards require steel with inclusions larger than 0.008mm be discarded – Dr Powell said the deformities in the crankshaft were 0.1mm wide, or 25 times larger than allowed.
He claimed the deformities severely weakened the crankshaft and caused it to fracture.
But yesterday Neville Blyth, the Australian Transport Safety Bureau's senior safety investigator, said the shaft contained no defects when he examined it months before Dr Powell.
"At no time did we observe the presence of any oxide inclusions, other than small globules – very small globules," Mr Blyth said.
"There was no evidence of anything we, as a group, consider would injure the metal . . . there were no material defects."
Mr Blyth said any deformities found by Dr Powell must have been created by the acids used in the testing process.
"The inclusions . . . were not present when I and my colleagues examined the specimen (of the crankshaft)," he said.
"On that basis, we are drawn to the conclusion . . . that they were man-made, rather than being in the metal . . . most likely a product of post-examination corrosion."
Mr Blyth maintained the crash of Flight 904 was caused by Whyalla Airlines' use of lean fuel mixes, which caused a build-up of lead particles on the plane's pistons.
But Peter Erikson, counsel assisting the Coroner, said Dr Powell had 30 years' experience with defects in steel.
Mr Blyth, meanwhile, was in his fourth week of employment with the ATSB when he studied the plane's crankshaft.
Mr Blyth admitted he had never studied a crankshaft before looking at the one in the engine of Flight 904, and had not examined one since.
"But I make my criticisms regardless of his (Dr Powell's) experience," he said.
Mr Erikson asked if a microscope or any other equipment had been used by the ATSB to check for oxide inclusions.
"The examination was conducted visually, there was no microscope used," Mr Blyth said.
The inquest – into the deaths of eight people
who were killed when the Piper Chieftan crashed
into Spencer Gulf on May 30, 2000 – is
continuing.