In flight break up
This sounds very much like the break up of R44 DQ IHE in 2006 in Fiji. Sudden change in sound, break up in flight. I was involved in that investigation and find it totally unbelievable that CAAFI have not released that report. They have had the report for several years now. Even if it turns out that the report bears no relevance to this incident, the investigators really should use the guidance provided in the report to eliminate the probable cause identified by that investigation. The most probable cause identified in the report has not been reported elsewhere and does have safety of flight implications. I would think that CAAFI have a duty of care to release the report, even if they disagree with the findings.
Regards
Blakmax