ROTAX Service Instruction SI-PAC-032 Air Restrictor for Optional Genuine Airbox for 912 Engines

ROTAX has released Service Instruction SI‑PAC‑032 introducing an optional preheated‑air restrictor for aircraft equipped with the genuine ROTAX airbox (part no. 667355). The restrictor is designed to help maintain correct fuel‑air balance when using preheated air—particularly in installations where extended use of carburetor heat or low‑octane fuel could otherwise risk engine damage.

This optional part fits into the airbox’s preheated‑air inlet and helps keep plenum pressure within safe limits across the operating range. It is not a certified part and must be validated and approved by the aircraft manufacturer as part of the aircraft’s system. Installation requires accurate measurement of manifold pressure and may involve machining the restrictor to suit the specific aircraft’s needs.

The Service Instruction is informational only (no mandatory compliance) and applies to all supported ROTAX engines using the referenced airbox design. All actions must be performed by appropriately qualified personnel and recorded in the engine logbook.