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All Rolls-Royce/Allison 250-C20 series, 250-C28 series, 250-C30 series and 250-C47 series engines fitted with a #5 bearing carbon seal with P/N 6898764.
To advise affected helicopter operators and maintainers of two recent occurrences of smoking Rolls-Royce/Allison 250 series engines, due to failure of OEM supplied #5 bearing carbon seal with P/N 6898764.
This Continuing Airworthiness Notice (CAN) is prompted by two recent failures of #5 bearing carbon seals with P/N 6898764. Both failures occurred soon after carbon seal replacement at a low number of flight hours. Fortunately the visible exhaust smoke prompted an immediate landing in both cases, before significant loss of engine oil pressure.
Rolls-Royce has been advised and the CAA is investigating whether similar failures have been reported to the FAA and EASA. The NZ maintenance provider that reported these incidents is assessing the situation to determine if these failures are limited to a recent batch of seals and if any other turbines are affected.
As information becomes available the CAA will keep operators and maintainers informed. Further action may most likely follow.
The CAA strongly recommends the following:
If any defects, occurrences or anomalies are found with #5 bearing carbon seals with P/N 6898764, then complete a CA005 Defect Report form and submit the completed form to the CAA at CA005@caa.govt.nz
Please include all findings and any other relevant technical information. A CA005D Defect Report form can be obtained from http://www.caa.govt.nz/assets/legacy/Forms/CA005D_Form.pdf(external link)
Please send enquiries regarding this CAN to:
Phone: 04 560 9569