Oil filter studs.
madrock,
One thing I noticed looking at pictures of the recovered hardware from the S-92 that crashed due to the MRGB oil filter housing failure, was that it had what appeared to be silver-plated locknuts on the housing's titanium studs. The combination of silver and titanium is usually not acceptable due to galvanic corrosion issues. This galvanic corrosion issue would also be exacerbated in a marine environment.
The FAA AD did not specifically mention this issue. But it is something they should have been aware of when qualifying the S-92's MRGB design.
Regards,
riff_raff