I'm just a dull old avionics engineer but I recall reading a previous AAIB Bulletin No: 8/2004 Ref: EW/C2003/02/06 Eurocopter AS332-L2, Super Puma, G-JSAR
The following are quotes from 8/2004:
Quote 1:
"Oil cooler drive shaft and gear wheel fractured. Bearing housing fractured"
Quote 2:
"The left hand accessory module was removed from the MGB and an internal examination revealed that the intermediate gear wheel had fractured from the bearing at the centre to the outer edge of the gear. Its bearing housing was also fractured through one of the three attachment lugs. The remaining two attachment lug bolts were found fully torque tightened. The detached portion of the failed lug was found lying loose within the module housing."
Quote 3:
"A similar incident occurred to another operator's AS332-L2, G-PUMS, on 21 November 2002, when an amber MGB oil pressure caption illuminated when the aircraft was on the ground following flight. On the subsequent ground run, the accessory gearbox seized, followed by the shearing of the oil cooling fan drive shaft. A large amount of debris was found on the MGB magnetic plug. Investigation of the left hand accessory module revealed that the intermediate gear had fractured into two pieces. In addition, there was associated damage to the internal surfaces of the casing. A photograph of the internal components of the module is shown at Figure 3."
Quote 4:
"Although neither of the two incidents described here occurred in the cruise, had they done so, the ability for continued safe flight was considered not to be compromised. Nevertheless, the fact that the MGB and the accessory modules share the same oil system could result in potentially serious contamination problems, thereby constituting a flight safety hazard."
http://www.aaib.gov.uk/cms_resources...pdf_030207.pdf