A couple buddies of mine had an engine quit in an S76-A. They were coming off a hospital helipad and it died shortly after rotation at about 100'. Flew away on the remaining engine and later elected to try relighting the failed engine, and got it going again without any further issues. Returned to base safe and sound.
The engine flamed out due to a fault in the fuel line. I guess at the time, the fuel lines in the C30 engines were not limited to a certain amount of hours before they need to be replaced. It's a typical steel-braided flex hose wrapped in insulation. Of course with it being a steel braided line, it should have immense rigidity. Well.... these had been in place so long that all that rigidity was gone. With just two fingers we could pinch it closed!!
When they started the fly-away and lowered collective to set normal climb power, that reduction in pressure in the fuel line caused a momentary vacuum effect and it pinched closed.
Not sure if Allison or Sikorsky issued a SB after that or not, but the lines in our whole fleet got changed out as a result.