Embrittlement of a helicopter rotorhead component

One of two drive pins in a helicopter swash plate assembly fractured resulting in the in-flight separation of the entire rotor system and total loss of the helicopter with two fatalities. The NTSB and the manufacturer examined the drive pin and determined the brittle fracture was the result of hydrogen embrittlement of the pin. The presentation will cover the details of the accident and the examination of the alloy steel pin.