Bulletin 54-088 -

Because commercial service literature expands over time, comparing the technical targets of related Group 54 updates helps mechanics understand the evolutionary changes in wiring topology: Bulletin Identifier Main Focus Area Expected Action Required Affected Systems Electrical Controls & Routing Inspection / Component Retrofit Wiring Harness / Control Modules SB 54-289 ICU2M to ICU4M Conversion Circuit relocation & physical gauge replacement Dashboard Instrumentation PTB 00-009 Parts Technical Verification Add global annotation in PartsPro database Inventory & Fleet Records

In the context of aviation, relates to modifications for the APU fuel tube on specific aircraft. bulletin 54-088