Rotax has issued a mandatory service bulletin requiring replacement of the turbocharger valve housing on certain 915 i and 916 i series engines before the next flight. The Sept. 3 bulletin applies to engines and spare turbocharger assemblies identified by serial number.
Cracks Found During Testing
Rotax identified oil leakage around the turbocharger valve housing during end-of-line testing. Further investigation found cracks and insufficient wall thickness in some housings caused by what the company said was a supplier manufacturing issue. Rotax classified the condition as unsafe because leaking oil could contact hot exhaust components, potentially producing smoke or, in the worst case, an engine-compartment fire.
The affected component is valve housing part number 956492. Certain spare turbocharger assemblies carrying part number 893102 are also affected and must have the housing replaced before installation. Rotax says later-production engines have received additional assembly-line checks and the affected housing has already been replaced.
Serial Numbers Determine Applicability
In order to comply with the bulletin, owners and maintainers must compare engine and turbocharger serial numbers with the lists included in the bulletin and review the engine logbook to determine whether a housing has previously been replaced. Stored engines and spare parts must be corrected before delivery, while uninstalled components must be corrected before initial installation.
Rotax says the work must be performed by authorized personnel, including technicians holding the applicable iRMT heavy-maintenance qualification. The company will provide labor credit for qualifying work through Rotax authorized distributors or service centers, and the completed replacement must be recorded in the engine logbook.
The turbocharger bulletin follows a separate Rotax issue addressed by the FAA last month. An airworthiness directive effective Aug. 28 requires inspections of about 180 U.S.-registered aircraft equipped with certain 912- and 914-series engines after Rotax discovered that some recently manufactured propeller gearboxes were assembled without an oil spray nozzle and screws used to secure the propeller shaft bearing. Gearboxes missing the components had to be replaced before further flight.
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