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 materials compatibility concerns and potential engine warranty invalidation.
This creates a dilemma for maintainers, as they must reconcile the fuel's legal FAA approval via STC with the manufacturer's advisory when returning aircraft to service.
GAMI, the fuel's manufacturer, disputes Cirrus's claims, citing extensive testing and long-term trouble-free use, while the FAA maintains G100UL's STC approval and clarifies that service advisories are typically not mandatory for Part 91 operations unless incorporated into an Airworthiness Directive.

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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.