Wärtsilä-Wichmann CPP Overhaul: Sterntube and Blade Seal Replacement
During a scheduled docking period, maintenance work was required on a Wärtsilä-Wichmann controllable pitch propeller (CPP) system. The primary challenge was not the replacement itself but the identification of the correct sealing components, as only limited technical documentation was available for the ageing installation. The project included analysis of available drawings, identification of installed sealing arrangements, replacement of sterntube and blade seals, inspection of the OD-Box assembly and subsequent functional testing of the pitch control system.
Initial Findings and Technical Challenges
During scheduled maintenance, traces of oil leakage were observed around the propeller hub and sterntube area. The installation had been in service for many years and only partial technical documentation was available. Before maintenance could begin, it was necessary to determine the exact sealing arrangements installed on the CPP system.
Documentation Review and Seal Identification
Available drawings, spare parts information and historical documentation were reviewed. The installed sealing components were compared with existing records and verified against measurements taken during disassembly. This process allowed the required replacement seals to be identified and sourced.
Sterntube and CPP Blade Seal Replacement
Following identification of the required components, worn sterntube seals and CPP blade seals were replaced. Sealing surfaces were inspected and prepared prior to installation. Particular attention was given to ensuring compatibility between the replacement components and the existing arrangement.
OD-Box Inspection and Functional Testing
The OD-Box assembly and associated hydraulic control components were inspected during the overhaul. After completion of the sealing work, the CPP system underwent functional testing. Pitch control operation was verified throughout the operating range and no further leakage was observed.
Prevention
Periodic inspection of sterntube and CPP blade seals, monitoring of oil consumption and maintaining updated technical documentation can significantly reduce downtime during future maintenance activities.
Measurable Results
- documentation status Partial documentation reviewed and verified
- seal identification Completed successfully
- sterntube seals Replaced
- cpp blade seals Replaced
- od box Inspected
- final result CPP system returned to service