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Incident Date: | Date of incident not available. |
Summary: | During routine maintenance the brake shaft of a lifeboat winch braking mechanism lock nut threads were found to be damaged. One of the lock nuts was lying within the cover of the brake mechanism, the other nut was still in place but the threads on both the shafts and the nuts were stretched and damaged. Due to this the brake disc mechanism had no reaction point to provide secure engagement. |
Incident consequences (potential or actual): | No details available. |
Cause of accident or incident: | No details available. |
Activity Location: | Floating production/storage unit |
Activity Type: | Maintenance |
Description: |
During routine maintenance the brake shaft thread & retaining / lock nuts threads were found to be damaged. One of the lock nuts was lying within the cover of the brake mechanism, the other nut was still in place but the threads on both the shafts and the nuts were stretched and damaged. Due to this the brake disc mechanism had no reaction point to provide secure engagement.
At the time the boat was secure in the davits and in no danger of dropping to the sea and, similarly, had the nuts failed while lowering the boat it’s decent would have been controlled by the separate centrifugal brake assembly.
Maintenance records indicate that the lock nuts on two boat winches had previously slackened off and been re-tightened. On inspection, a recently installed davit was found to have a modified and improved type of locking arrangement. The modified arrangement is being fitted to the installation’s davits.
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Specific Equipment: | No details available. |
Lessons Learnt: | The inspection & maintenance programme needs to be robust enough to pick up this type of defect. |
Task Description: | No details available. |
Recommendations: | Inspect all Davit International 18 kNm winches for this problem and repair/modify as appropriat |
Contact Details: | Colin McIntosh, tel 01224 835005 |
Figures: | Original locknut
Revised locknut design
Overview
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| Posted: 8/12/2006 |
Usage details: |
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