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###### Department of Transportation

###### Federal Aviation Administration

# AGENCY:

Federal Aviation Administration (FAA), DOT.

# ACTION:

Notice of issuance of advisory circular.

# SUMMARY:

This notice announces the issuance of Advisory Circular (AC) 20-24C, Approval of Propulsion Fuels and Lubricating Oils. This AC provides guidance on regulations and policy applicable to adding fuels and oils to type certificates as engine, aircraft, or auxiliary power unit (APU) operating limitations. It also provides acceptable methods, but not the only methods, that may be used to approve aircraft, engines, or APUs to operate with specified propulsion fuels and lubricating oils.

# DATES:

The Engine and Propeller Directorate issued AC 20-24C on July 29, 2011.

# FOR FURTHER INFORMATION CONTACT:

                        The Federal Aviation Administration, Attn: Mark Rumizen, Aviation Fuels Specialist, Engine and Propeller Standards Staff, ANE-110, 12 New England Executive Park, Burlington, MA                               ( print page 49526)                            01803-5299;                         *telephone:*                         (781) 238-7113;                         *fax:*                         (781) 238-7199;                         *e-mail: mark.rumizen@faa.gov.*

                        Comments were submitted to the FAA during the period the draft AC was posted for public viewing on the FAA's Aviation Safety Draft Documents Open for Comment Web site. The disposition of these comments can be viewed at the FAA's Regulatory and Guidance library Web site (                        *http://rgl.faa.gov/​Regulatory_​and_​Guidance_​Library/​rgAdvisoryCircular.nsf/​Frameset?​OpenPage*).                    

# SUPPLEMENTARY INFORMATION:

AC 20-24C cancels AC 20-24B and describes established methods of adding fuels and oils as engine, aircraft, or APU operating limitations. These established methods reflect procedures and practices employed by the Engine and Propeller Directorate (EPD) for oversight of successful aviation fuel and lubricating oil certification projects conducted over many years. These procedures and practices have essentially relied on fuels and oils grade or brand designations that were identified by industry voluntary consensus-based, military, or other governmental standards.

A draft of this AC was made available for public comment on September 1, 2010, for a period of 60 days. The FAA received many comments regarding the use of other, new and novel methods to add fuels and oils as engine, aircraft, or APU operating limitations in lieu of the methods described in the AC. However, the EPD cannot develop guidance describing other, new and novel methods until we gain sufficient certification oversight experience with these projects. Therefore, the final AC does not contain guidance on these new and novel methods to add fuels and oils as engine aircraft, or APU operating limitations.

*How To Obtain Copies:*                     A paper copy of AC 20-24C may be obtained by writing to the U.S. Department of Transportation, Subsequent Distribution Office, DOT Warehouse, SVC-121.23, Ardmore East Business Center, 3341Q 75th Ave., Landover, MD 20785, telephone 301-322-5377, or by taxing your request to the warehouse at 301-386-5394. The AC will also be available on the Internet at                     *http://www.faa.gov/​regulations_​policies*                     (then click on “Advisory Circulars”).                

Authority: 49 U.S.C. 106(g), 40113, 44701-44702, 44704.

Issued in Burlington, Massachusetts, on July 29, 2011.

Peter A. White,

Acting Manager, Engine and Propeller Directorate, Aircraft Certification Service.

[FR Doc. 2011-20324 Filed 8-9-11; 8:45 am]

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