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The purpose of this Continuing Airworthiness Notice (CAN) is to inform aircraft operators and maintenance providers that the CAA recently became aware of a clutch assembly defect (i.e. spalling damage to a C166-5 shaft). There have been several mid-life sprag failures in R44 helicopters over the past 15 years. In response to these failures the CAA issued DCA/R44/23B to inspect the clutch oil for contamination every 500 hours TIS. The damaged shaft was not found as a result of an inspection in accordance with DCA/R44/23B and there were no sprags found damaged or broken.

This CAN is prompted by CAA awareness of several cargo hooks in New Zealand being damaged due to torsional loads. Loads attached to a cargo hook with a spreader bar (e.g. a fertilizer bucket) may cause the cargo hook to be subjected to high torsional loads which can damage the cargo hook. To ensure continued airworthiness of the hook, additional inspections, certain on-condition repairs, and/or appropriate replacement actions have been added to the manufacturers CMM. Refer to Onboard Systems CMM 122-015-00 for the new/additional inspections required for cargo hooks used for torsional load applications.

This Continuing Airworthiness Notice (CAN) alerts operators of affected helicopters of the risk of fuel contamination when refuelling in dusty environments and mitigate the risk with good fuel-handling procedures when operating at remote locations.