CJ4 Operators: What is Service Bulletin WISB-72-1023 and why it’s important

Williams International issued WISB-72-1023 (Link to PDF Here) after identifying an issue in the Intermediate Pressure Compressor Rotor (IPC).  Due to a machining issue during manufacturing, the rotor as it ages can induce cracking and blade displacement as a small number of FJ144-4A engines have had this occur.  Blade loss in this manner can result in noise, vibration, or change in operating parameters of the engine.

The manufacturer’s Service Bulletin recommends replacement of this rotor at next MPI and can be completed on-wing, at a Williams-authorized Line Maintenance Elite Service Center.  West Star Aviation (ALN) was approached by Williams International through a joint venture to become one of 3 sources in the United States and 5 in the world to accomplish these Service Bulletin replacements.

West Star Aviation completed in-depth training in late 2021 with Williams International and now has the necessary tooling staged to assist Williams International in upgrading the CJ4 fleet.  Specifically, Service Bulletin WISB-72.1023, calls for replacing the intermediate Pressure Compressor Rotor

With factory training complete and the necessary tooling staged at West Star Aviation (ALN), the first IP Rotor Change is in work at the facility and has events scheduled into October 2022.   The down-time for the rotor change is approximately five days, depending on outgoing vibration tests and if there is other airframe maintenance scheduled.

The Williams International Authorized Service Centers in the list below are equipped to perform this maintenance. Please directly contact the center of your choice in the list to schedule this maintenance: