Impurity Control and Technical Justification in Synthetic Aviation Turbine Fuel Standards

The standard practice for evaluation of new aviation turbine fuels and fuel additives (ASTM D4054), which instructs the qualification production pathways of synthetic blend components (SBC), lists 53 materials (classes of or specific elements or molecules) whose concentration in fuel should be less than 1% by mass (% m ). Additionally, 18 properties that could be impacted significantly by trace levels of certain materials in fuel are referenced in that standard practice, each with some controlling guidance. This work examines the technical risks that these fuel-quality requirements are intended to mitigate. Potential issues include excessive deposition of solid or gelatinous material, material compatibility, wear, fuel toxicity, or other safety considerations. These issues could manifest themselves anywhere within the aircraft/engine fuel system, fuel handling equipment upstream of the aircraft, the hot section of the engine, emissions, and fuel additives. Additional concerns include the potential confounding of deposit forensics, which may complicate root cause investigations of unscheduled engine removals. Our intention here is to highlight published works that address some of these issues and document where gaps exist in the archival literature.