About 2 years ago Herman Hospital in Houston, TX lost a BK117 due to a
M/R blade loss. They were on approach, I seem to recall about 100 ft
AGL, and broke a TT strap (badly corroded). The M/R gearbox left the
aircraft and all 3 souls were lost.

And caused the subsequent grounding
of many BK117s in the EMS community
as they had to do an inspection. But I think most ships were quickly back in
service.