Skip to main content

Type Certification of Oxygenates and Oxygenated Gasoline Fuels in Part 23 Airplanes with Reciprocating Engines

AC 23.1521-2 · FAA

Public domain · FAAAdvisory Circulars

Overview

The Type Certification of Oxygenates and Oxygenated Gasoline Fuels in Part 23 Airplanes with Reciprocating Engines (AC 23.1521-2) is a public-domain FAA advisory circular, republished here as a free chaptered HTML edition with a linked table of contents and the official PDF.

Publisher
FAA
Document
AC 23.1521-2
Pages
17
Chapters
2

Key points

  • This advisory circular (AC) provides guidance on the certification of oxygenates and oxygenated gasoline fuels for Part 23 airplanes with reciprocating engines.
  • The AC clarifies that the procedures for certification of alternate fuels also apply to airplanes approved under previous regulations.
  • Mixing of alternate fuels is prohibited unless the mixture is separately certified and documented by an approved fuel specification.
  • A Supplemental Type Certificate (STC) or Type Certification (TC) is required for each different series or sub-series of engine and airplane models for which approval is requested.
  • The fuel for which approval is requested must be documented by a specification detailing its composition, physical properties, and limits.
Frequently asked questions
What is the purpose of this advisory circular?

The purpose of this advisory circular is to provide information and guidance concerning acceptable means of compliance with part 23 of the Federal Aviation Regulations for the certification of alternate fuels.

Are the procedures outlined in this AC mandatory?

No, the material in this advisory circular is neither mandatory nor regulatory in nature and does not constitute a regulation.

What types of fuels are covered by this advisory circular?

The fuels covered include oxygenates and oxygenated gasolines, such as methyl-tertiary-butyl ether (MTBE), methanol, ethanol, and gasolines containing these or other oxygenates.

What is required for a fuel to be approved for use in an airplane?

The fuel must have a documented specification that defines its properties, and it must be shown to be compatible with the engine and airplane materials.

What is the significance of the STC or TC in relation to alternate fuels?

An STC or TC is required for each different series or sub-series of engine and airplane models for which approval is requested, ensuring that the airplane meets applicable regulations.

Appendix 1

1/21/93 AC 23.1521-2 Appendix 1 APPENDIX 1. ADVISORY CIRCULARS The publications listed below may be obtained from the U.S.

Department of Transportation, Utilization and Storage Section, M-443.2, Washington, D.C. 20590. Advisory Circular (AC) 23-8A can be obtained from the Superintendent of Documents, U.S. Government Printing Office, Washington, D.C., 20402, or from any of the Government Printing Office bookstores located in major cities throughout the United States.

1. Qualification of Fuel, Lubricants, and Additives for Aircraft Engines , AC 20-24B, Federal Aviation Administration, December 20, 1985.

2. Aircraft Fuel Control , AC 20-43C, Federal Aviation Administration, October 26, 1976.

3. Protection of Airplane Fuel Systems Against Fuel Vapor Ignition Due to Lightning , AC 20-53A, Federal Aviation Administration, April 12, 1985.

4. Water in Aviation Fuels , AC 20-125, Federal Aviation Administration, December 10, 1985.

5. Flight Test Guide for Certification of Part 23 Airplanes , AC 23-8A, Federal Aviation Administration, February 9, 1989.

6. Substantiating Flow Rates and Pressures in Fuel Systems of Small Airplanes , AC 23.955-1, Federal Aviation Administration, June 10, 1985.

7. Unusable Fuel Test Procedures for Small Airplanes , AC 23.959-1, Federal Aviation Administration, January 14, 1985.

8. Procedures for Conducting Fuel System Hot Weather Operation Tests , AC 23.961-1, Federal Aviation Administration, January 14, 1987.

9. Certification of Non-Oxygenated Automobile Gasoline (Autogas) instead of Aviation Gasoline (Avgas) in Part 23 Airplanes with Reciprocating Engines , AC 23.1521-1A, Federal Aviation Administration, January 2, 1991.

10. Detonation Testing in Reciprocating Aircraft Engines , AC 33.47-1, Federal Aviation Administration, June 27, 1988.

11. Use of Alternate Grades of Aviation Gasoline for Grade 80/87 , and Use of Automotive Gasoline , AC 91-33A, Federal Aviation Administration, July 18, 1984.

1 (and 2)

Next: Appendix 2 →

Appendix 2

1/21/93 AC 23.1521-2 Appendix 2 APPENDIX 2. RELATED READING MATERIAL 1. Automotive Fuels Handbook , Society of Automotive Engineers, (SAE), 1990.

2. Alternate Fuels for General Aviation Aircraft with Spark Ignition Engines , DOT/FAA/CT-88/05, Federal Aviation Administration, March 1988.

3. The Performance of Alternate Fuels in General Aviation , DOT/FAA/OT-88/13, Federal Aviation Administration, July 1988.

4. Straight Alcohol Fuels for General Aviation Aircraft , SAE Paper 891038, General Aviation Aircraft Meeting and Exposition, April 11 13, 1989.

5. Alcohols and Ethers, A Technical Assessment of Their Application as Fuels and Fuel Components , API Publication 4261, Second Edition, July 1988.

6. Aviation Fuels , Maxwell Smith, G. T. Fouks & Co. Ltd., 1970.

7. Powerplants for Aircraft , Joseph Liston, McGraw-Hill Book Company, Inc., 1953.

8. Internal Combustion Engines and Air Pollution , Edward Obert, Intext Educational Publishers, 1973.

1 (and 2)

Source & rights

Source: faa.gov. Public-domain U.S. Government work (17 USC §105) — freely reproducible.

View the official PDF at faa.govDownload PDF

Permanent URL — we don’t break links.

Report a problem or request removal

Document details

Doc number
AC 23.1521-2
Publisher
FAA
Pages
17
File size
69 KB
Chapters
2
All Advisory Circulars
What to do next
Browse FAA documents
All FAA handbooks, rules & guides
All regulations & handbooks
Every authority, chaptered and searchable
Identify an aircraft
Look up a tail number or match a type
Aircraft for sale
Browse the marketplace