ballpoint: not exclusively limited to P&W motors. As you may recall that on May 25, 1979 at ORD, engine No.1 came unglued and rotated over the wing of a GE powered DC-10-10. In the mid 90s a Rolls Royce RB211 had separated from a TriStar after takeoff at MIA.
Engine separation has more to do with maintenance (corrosion/metal fatigue) of pylons and attach fittings, rather than engines. Pylons, attach fittings, bolts, thrust links and engine nacelles/cowlings are airframe parts.