The FAA has published for public comment a draft advisory circular: AC 20-24D, Approval of Propulsion Fuels and Lubricating Oils.
Since the 2009 revision to the FAA’s manufacturing regulations, all materials and other articles for aircraft have been required to be approved by the FAA under PMA, TSOA, or PC or to fall into one of the stated exceptions found in 14 C.F.R. 21.9. This means that lubricating oils are required to be approved or to be manufactured and made available under a standard. The guidance in 20-24D makes it clear that the SAE standards specify testing standards for lubricating oils but that they are insufficient to reflect a standard for production purposes; and therefore the FAA must approve lubricating oils (e.g. through the TC for original oils, and though other means like STCs for subsequently defined oils).
The guidance appears to be out-of-date relative to the 2009 changes to the FAA’s regulations in light of the fact that it does not address production approval. Thus, the concerns with the regulations are not necessarily with the proposed revisions, but rather with the failure of the proposed revisions to bring the guidance up to the existing regulatory standard.
The guidance omits any mention of PMAs for oils, and proceeds as if PMAs were unnecessary. In light of the fact that the FAA has issued PMAs for lubricating oils, this omission seems important. Additionally, as mentioned above, 14 C.F.R. 21.9 now appears to require production approval.
Also, the fact that the FAA has issued PMAs for lubricating oils seems to create an uneven playing field is some participants in the marketplace are not required to obtain PMAs or other production approvals.
The guidance also talks about needing engine manufacturer approval for new lubricating oils. In light of the fact that some PMA holders for lubricating oil are independent of the engine manufacturer, it would appear that the guidance creates a situation where engine manufacturer approval would become a condition for market entry. This appears to potentially violate the Sherman Act .
Comments are due to the FAA at the end of September, so please get us YOUR comments by September 16 so we can make sure we address your concerns in the MARPA comments.