King Air PT6 question
From my understanding (which may be misguided) the older PT6s had microscopic holes near the tips of the compressor blades that would melt in the case of an overspeed and decrease the efficiency of the turbine to slow the engine (permanently speaking of course). From what I understand this was for redundancy in case the prop, overspeed, and fuel governors all fail. Do these holes (or the blades themselves) have a particular name?