Good job by the PIC.
I'm assuming this failure mode is covered during FSI.
Just highlights how media-sensitive the S92 is right now, and rightly so.
"Trust the pilots, who trust the engineers, who trust the designers"...a wee bit of trust breakdown in this case. These maintenance "errors" are totally unacceptable, would have been more than a ASB if this had ended up in fatalities, thanks to the PIC's skills this wasn't the case.
What's to prevent this happening again, enhanced awareness is good but procedural auditing etc. is what's really required. This was also an issue with Cougar 491. From the TSB report, under the conclusions section:
Cougar Helicopters did not effectively implement the mandatory maintenance procedures in Aircraft Maintenance Manual (AMM) Revision 13 and, therefore, damaged studs on the filter bowl assembly were not detected or replaced.
Safe flying
Max