Argentinean investigators have determined that pitting corrosion led to a fatigue failure, causing the nose-wheel of an Embraer 190 to detach before take-off from Mar del Plata's Astor Piazzolla airport.
The Austral Lineas Aereas aircraft (LV-CID) had been taxiing for runway 31, in preparation for the service to Buenos Aires, on 29 January last year.
Its left-hand nose-wheel separated as it taxied. Overload sensors in the nose-wheel steering system revealed no anomalies and flight-recorder data shows the nose-wheel rotation was within normal parameters at the time.
None of the 98 occupants was injured.
Examination of the fracture found evidence of corrosive pitting, leading to a fissure, but the precise mechanism for the failure remains unclear.
Investigation authority JIAAC says it was "not possible to determine with certainty" why the fissure spread to the point of fracture without being detected by non-destructive testing during intermediate inspections.
The inquiry suggests the corrosion could have caused the crack to propagate at high speed, sufficient to escape notice.
But it points out that there was no "concrete evidence" of inadequate maintenance procedures. The carrier has its own maintenance workshop.
JIAAC states that manufacturers Meggitt Aircraft Braking Systems and Liebherr-Aerospace, as well as Embraer and the US National Transportation Safety Board took part in the investigation.
But it believes that the incident remains an "isolated" event, with no indication of similar previous failures on the aircraft type.
Meggitt analysis shows that nose-wheels on Embraer 170 and 190 jets are subjected to some 4 million landings annually, and that the absence of prior failure suggests maintenance inspection processes for the assemblies are suitable.