Future Aircraft Fuels – Diamond Aircraft and 100LL

Posted on October 22, 2012

Many aircraft owners fret the future availability of 100LL fuel for their piston-engined aircraft. Should the Diamond DA40 owner be worried? Answer: NO!

No one should be worried about possible unavailability of 100LL obsoleting their DA40. Future fuel compatibility is an integral part of the design concept of the DA40, and these issues were contemplated during the design phase in the late 1990’s.   The airframe itself is inert with respect to new fuels by design:

  • Aluminum fuel tanks
  • Teflon fuel lines
  • Other elastomeric polymers which are multi-fuel compatable

Other aircraft types may have problems with incompatible material/fuel combinations, such as:

  • composite wet wings
  • rubber bladder tanks
  • seals
  • fuel lines, etc

As for the Lycoming IO360 and future fuels, that engine has at least three paths forward for the IO360 without 100LL

  1. Lycoming may certify the engine for automotive fuel, paving the way for the certification of the DA40 to use auto fuel.
  2. The IO360 is already certified for 91UL, an existing spec aviation fuel that may be reintroduced to the market.  Certification of the DA40 would require some flight testing and perhaps relatively minor modifications.
  3. New fuels may emerge with octane ratings of 94 and above.  As the IO360 would work with any of these, certification of the DA40 with such future fuels would require at most some minor modifications.

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