Cirrus Service Advisory Throws Fuel on G100UL Maintenance Debate

The SA creates a potential dilemma for aircraft maintainers.

Richard Scarbrough

Tuesday, July 16, 2024 at 11:51 AM ET

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Edited By:

Ryan Ewing

GAMI is disputing Cirrus’s claim that use of G100UL voids the warranties on engines supplied by Lycoming and Continental and used in its aircraft. [Credit: Shutterstock]

Key Takeaways:

Cirrus issued a service advisory against using FAA-approved G100UL fuel in its SR Series aircraft, citing inconclusive material compatibility and potential warranty voidance from engine manufacturers.
This creates a dilemma for aircraft maintainers: G100UL is legal per FAA STC, but manufacturers' non-approval complicates signing off aircraft as "returned to service in accordance with OEM guidelines."
While FAA service bulletins are generally advisory for Part 91 operations unless they become an Airworthiness Directive, maintainers must document if actions align with OEM information or an alternate, FAA-approved method.
GAMI, the developer of G100UL, disputes Cirrus's concerns, asserting extensive testing has shown no issues with their fuel.

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In June, Cirrus released a service advisory (SA) regarding the use of fuel that had not been approved for SR Series aircraft. This creates a dilemma for many, including aircraft maintainers.

The issue of what is legal (in FAA terms) and approved (by manufacturers) puts maintainers in a sticky situation. On one hand, the FAA issues a supplemental type certificate (STC) allowing for products to deploy on aircraft, but the engine and/or aircraft manufacturer may not approve or recognize the STC as something permitted for use under the terms of their warranty.