You are mistaken Mitchaa, the cracks were not in identical locations (though they were near-by).
Why did Eurocopter allow this 2nd failure to happen? What was being done in the months between May and October to protect the remaining 225 fleet? Why didn't Eurocopter identify the issue correctly?
As the AAIB explain in their report, the corrosion in the G-REDW case was believed by
all the parties to the investigation (prior to G-CHCN), to be linked with a tiny production anomaly in a countersunk hole in one batch of shafts. The AAIB list 7 actions that Eurocopter took to address that.
In contrast, to show a really inadequate response, the first S-76 fatal accident (
PT-HKB) in which 14 died after a main rotor blade came off occurred less about a year before another 4 people died due to an identical failure (
G-BGXY). In this S-76 case a key inspection requirement was dropped from the Service Bulletin after PT-HKB, and despite the FAA chasing Sikorsky, they had not acted by the time of the UK accident.
G-REDL
Bond said they told Eurocopter that the chip had come from the epicyclic plug. Eurocopter denied this and said Bond had told them it had come from the main module sump.
Eurocopter were no doubt confident they were
told the debris was found in the sump because when debris is found on the epicyclic detector the epicyclic module
has to be opened and the magnets examined. The operator did not follow the MM requirement to do that and therefore was unable to tell Eurocopter anything about the magnets. The absence of that data would reinforce a misunderstanding at Eurocopter that the chip was found in the sump.
The operator was of course aware of where the chips were found and what maintenance they had and hadn't done, which they found it impossible to explain at the Fatal Accident Inquiry.