The Rotax 912 iS2 engine is designed to operate on a variety of fuels, making it versatile and compatible with different aviation needs. The primary recommended fuels for this engine are premium unleaded automotive gasoline (MOGAS) that meets EN 228 or ASTM D4814 specifications and Rotax 912 is2 aviation gasoline (AVGAS 100LL). This flexibility allows operators to choose fuel based on availability and cost, especially in regions where one type may be more accessible than the other.

Recommended Fuel Types

1. MOGAS (Premium Unleaded Gasoline):

   • The Rotax 912 iS2 is optimized for premium unleaded gasoline with an octane rating of at least 91 RON (Research Octane Number).
   • This fuel type is widely available at automotive gas stations, making it cost-effective for pilots operating in areas where aviation gasoline is less accessible.

2. AVGAS 100LL (Low-Lead Aviation Gasoline):

   • AVGAS 100LL can be used as an alternative when unleaded gasoline is not available. However, due to its lead content, regular use of AVGAS may lead to deposits in the engine, necessitating more frequent maintenance.

Compatibility with Ethanol Blends

The Rotax 912 iS2 can handle ethanol-blended fuels but with specific limitations:

• Fuels with up to 10% ethanol (commonly labeled as E10) are approved for use.
• Ethanol content beyond 10% is not recommended, as higher concentrations can lead to issues such as corrosion in fuel system components, vapor lock, and reduced engine reliability.

Operators should verify the ethanol content of locally available fuels to ensure compatibility. Using high-ethanol blends (e.g., E15 or E85) can void the warranty and pose risks to engine longevity.

Advantages of Fuel Versatility

The ability to use both unleaded automotive gasoline and aviation gasoline gives pilots flexibility:

• Cost Savings: Unleaded automotive gasoline is often more affordable than AVGAS, significantly reducing operating costs for pilots and aircraft owners.
• Availability: In areas where AVGAS is scarce or expensive, the ability to use premium unleaded gasoline ensures uninterrupted operation.
• Environmental Benefits: The lower lead content in MOGAS makes it an environmentally friendlier choice compared to AVGAS 100LL.

Considerations for Fuel Selection

When choosing fuel for the Rotax 912 iS2, pilots should consider:

1. Operational Environment: Availability of fuel types in the region and the altitude or temperature conditions that may affect engine performance.
2. Maintenance Impact: Prolonged use of AVGAS may increase lead deposits in the engine, requiring additional cleaning and maintenance.
3. Fuel Quality: Always use high-quality fuel free from contaminants and store it properly to avoid degradation, especially for ethanol-blended fuels.

Conclusion

The Rotax 912 iS2’s support for multiple fuel types, including MOGAS, AVGAS 100LL, and ethanol blends (up to 10%), makes it a versatile and efficient engine choice for light-sport and ultralight aircraft. Pilots should prioritize premium unleaded gasoline for regular operation to optimize performance and reduce maintenance needs, while using AVGAS as a reliable backup when necessary. Proper fuel management and adherence to Rotax’s guidelines are essential to ensure the engine’s longevity and safety.