Originally Posted by
squib66
You are mistaken Mitchaa, the cracks were not in identical locations (though they were near-by).
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
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.
I think your doing the REDL investigation a major disservice by selectively quoting part of the report the suit your argument. The issues around the discovery of the particle are clearly described in detail in the report, in summary, for various reason BOTH bond and EC made assumptions based on incomplete information.
Steps were taken to prevent it happening again which are clearly explained in the report.
I would also say that based on the report and the AAIB's testomony to the FAI, the AAIB do not support the EC/AH theory of 'pure' spalling that wasn't picked up by the operator. I for one would tend to support the AAIB view for two reasons, 1) they are independent and are not subject to commercial pressure, 2) they have access to information and expertise beyond that provided by EC.