Service Instruction No. 1143 C
Counterweight Bushing Inspection, Replacement, and Special Tooling Upgrades
Supersedes Service Instruction No. 1143B, Supplement No. 2, 3 and 4 to Service Instruction No. 1143B and Service Letter No. L217
November 10, 2011
All Lycoming piston aircraft engines with dynamic counterweights
TIME OF COMPLIANCE
During engine overhaul.
This Service Instruction includes all of the necessary information to examine, remove, prepare, and install counterweight bushings. Because of counterweight manufacturing changes, some modifications to existing tools used to replace counterweight bushings could be necessary. Instructions for tooling modifications also are included in Appendix A of this Service Instruction.
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