LEAF 2021

24 HR ORDERS 1-800-532-3462 ONLINECATALOG.LEADINGEDGEAIRFOILS.COM Prices and Supplies are subject to change without notice ROTAX ® COOLING SYSTEMS ROTAX ® 447 UL SCDI and 503 UL DCDI Fan Cooling System • The engine driven cooling fan provides sufficient cooling air, provided that the cooling air has free access and the hot air is not recirculated to the fan. • On aircraft equipped with engine cowlings the exit must be of sufficient size and in a low pressure area allowing the air to cool engine cabin and crankcase. ROTAX ® 447 UL SCDI and 503 UL DCDI Free Air Cooling System • Means ram air cooling, for engines without a fan. • In case of a tractor propeller configuration, with the propeller blowing air into the cylinder(s), this airstream serves for engine cooling. • On 2-cylinder engines the air stream must be directed from the exhaust side towards the carburetor side with suitable ducting (available from ROTAX ® ). • Pusher propeller configurations should not be used with free air cooled engines without consulting the engine manufacturer (in writing). Cooling Circuit for engine installation with Spark Plugs Down • For this installation position, a venting hose must be connected on top of the water pump housing (4) leading to the expansion chamber (10) or to the water chamber of the radiator. • Vent the cooling system well, check after a short operating period and refill coolant as required. Only a perfectly vented cooling system will operate satisfactorily. WARNING: Do not open cooling system until engine has cooled to outside temperature, failure to respect this information will result in severe scalds and injuries. 1. Crankcase 2. Cylinder 3. Cylinder Head 4. Water Pump 5. Radiator 6. Hose from radiator to water pump. 7. Hose from cylinder head to radiator. 8. Radiator screw cap, with excess pressure valve and return valve. 9. Temperature gauge for cooling water. 10. Overflow Hose 11. Overflow Bottle 12. Bottle Venting 13. Expansion Tank 14. Cylinder Head Venting Hose 15. Excess Pressure Valve 16. Return Valve ROTAX ® 582UL and Liquid Cooling System Cooling Circuit for engine installation with Spark Plugs Up • These engines have an integrated water pump. The cooling circuit must be arranged as shown. Coolant • Use silicate and phosphate free Dex-cool anti-freeze/coolant mixed with distilled water in all ROTAX ® liquid cooled engines. Coolant Flow • Should be in the range of 60 - 70 liters/min. at engine RPM 6500. Cooling Liquid Temperature • The average coolant temperature must be 60-80˚C (140-175˚F). • In case of a pusher propeller installation, take particular care of that coolant radiator has sufficient air flow. • The maximum temperature difference of the coolant between radiator entry and exit must not exceed 6˚C (11˚F), the average difference must be around 3 and 5˚ C (5 and 9˚). Cooling System • To avoid coolant pump cavitation, the cooling system must be under pressure of approximately 0,9 bar (13 psi). • The coolant hoses must be installed in such a way that air and steam bubbles can escape from any point of the system towards the expansion chamber. • The overflow hose (10) coming from the radiator neck is to be led into a vented overflow bottle (11). It should be half filled with coolant. The overflow hose must reach into the coolant or enter at the bottom of the overflow container. • The overflow bottle should be fitted not lower than 250 mm (10 in) below the radiator cap. 116