CHI85IA032

Shortly after takeoff, the flight crew heard a noise from the right side of the aircraft, which sounded like an engine compressor stall. The #3 engine was shut down & the crew made an uneventful landing at the departure airport. Pieces of cowling from the right engine fell in a residential area, but did no damage. Teardown of the engine revealed that turbine blades on the first stage low pressure turbine wheel had broken off & had penetrated the engine case & core cowl doors. Further investigation revealed that 2 stud bolts (saddle bolts) had pulled out from strut bosses 2 & 3 in the turbine mid frame (tmf), which placed an additional load on strut bosses 1 & 4. Eventually, the 1 & 4 saddle bolts pulled loose & allowed the nozzle support flange to shift rearward. This shift allowed the nozzle segments to come in contact with the low pressure turbine & result in the failure. There was indication that unauthorized rework had been acomplished on the saddle bolts before owner (united airline) had purchased the airplane from another (laker) airline.