AC 21-23A

Historical

Advisory circular · Airworthiness Certification of Civil Aircraft, Engines, Propellers, and Related Products Imported to the United States

A newer version is currentThis is a historical version. AC 21-23B is the version in force, approved November 17, 2004.
Approved
October 20, 2000
Last reviewed
July 1, 2003
Cancels
AC21-23
Cancelled by
AC21-23B
Family
AC 21-23 · 3 versions
Revision
A
14 CFR parts
21

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed November 22, 2025.

Show pages 40–51

43 CHAPTER 5. CONTINUED AIRWORTHINESS

5-1. GENERAL

a. Bilateral agreements provide for close cooperation between countries in the resolution of safety issues that can arise from in-service operation of any product exported/imported and approved or accepted under the terms of the agreement. When a safety concern arises, the FAA cooperates with its partner to determine the appropriate corrective action to be taken by operators or owners of affected U.S.-registered aircraft. The FAA expects exporting CAA’s to keep it informed of corrective actions that they believe are required for the safety of U.S.-registered aircraft.

b. The FAA also works closely with its counterpart authority to approve changes to type designs. These changes may consist of design improvements, changes necessary for continued airworthiness, repair information, or customer options.

5-2. CONTINUED AIRWORTHINESS DOCUMENTS

a. Continued Airworthiness Service documents (e.g., service bulletins, structural repair manuals, supplemental structural inspection documents), approved by the airworthiness authority of the country where an affected product is manufactured, are considered to be FAA-approved unless otherwise noted in a specific bilateral agreement. However, service bulletins or other similar instructions classified as "mandatory" by the exporting CAA are not mandatory under 14 CFR unless required by an FAA AD.

b. Owners or operators of affected U.S.-registered aircraft or engines, propellers, appliances and parts (i.e., products) are not required under U.S. law to comply with service documents or directives issued by the airworthiness authorities of other countries unless an FAA AD is issued under 14 CFR part 39. FAA AD’s are published in the Federal Register. AD’s issued during the current calendar year are available on the Internet at http://av-info.faa.gov. Information for ordering AD’s can also be obtained from the FAA’s Airworthiness Programs Branch, AFS-610, P.O. Box 25082, Oklahoma City, Oklahoma, 73125.

c. The FAA is committed to sharing safety critical information as soon as possible with its bilateral partners. FAA maintains an automated data base of all service difficulty reports received from the aviation community, including reports on imported products. This data is available on the Internet at http://av-info.faa.gov.

d. The FAA has filed an official difference with ICAO over the ICAO requirement for states to require that a system exists to transmit continuing airworthiness information to type design organizations. (See ICAO Annex 8, Part II, paragraph 4.2.5.) Instead, the FAA shares significant information with the certificating authority. In addition the FAA makes its Service Difficulty Reporting (SDR) system database available on the Internet at the address listed in c. above.

5-3. NOTIFICATION OF UNSAFE CONDITION AND MANDATORY CONTINUING

AIRWORTHINESS ACTIONS

a. When an exporting CAA issues a mandatory continuing airworthiness action for an unsafe condition that exists in a product, the FAA evaluates the information provided by the exporting CAA about the unsafe condition to determine whether the condition is likely to exist or develop on another product of the same type design. The exporting CAA should provide the FAA the following information:

(1) Make, model, and serial numbers of the affected product;

(2) Description of the unsafe condition, reasons for the mandatory action, and its impact on the affected aircraft and its continued operation;

(3) Description of the cause of the unsafe condition (e.g., stress, corrosion, fatigue, design problem, quality control, suspected unapproved part);

(4) The means by which the unsafe condition was detected and, if resulting from in-service experience, the number of occurrences;

(5) Corrective actions and corresponding compliance times, with a list of the relevant manufacturer’s service information, including reference number, revision number and date;

(6) The number of aircraft world-wide needing corrective action;

(7) A statement on the availability of parts; and

(8) An estimate of the number of labor hours and the cost of parts required for the corrective actions.

b. When an exporting CAA does not issue a mandatory continuing airworthiness action, but the FAA determines that one may be necessary, the exporting CAA should facilitate the manufacturer’s providing sufficient information, including service bulletins, to the FAA in a timely manner for use in evaluating the need for an AD.

c. Continued airworthiness information should be sent to the FAA’s Airworthiness Programs Branch, AFS-610, P.O. Box 25082, Oklahoma City, Oklahoma, 73125.

45 (and 46)

5-4. DESIGN CHANGES.

a. Following the type certification of an aircraft, it frequently becomes necessary to revise data on the aircraft type design. Major changes to a type design not great enough to require an application for a new TC, sought by the TC holder, may be issued as amendments to the type certificate issued under 14 CFR 21.29, or otherwise approved by the FAA. A certification procedure similar to that described in Chapter 2 is conducted and adjusted for the magnitude and complexity of the design change. The FAA retains the right to determine whether the proposed change is substantial enough to require a new type certificate for the changed type design.

b. Major changes to a type certificated design (for aircraft, aircraft engines, and propellers) which do not require an application for a new type certificate may also be approved through the issuance of a U.S. STC. Minor changes made by the type certificate holder are considered approved by the FAA upon approval by the exporting CAA under its normal procedures.

c. Each voluntary change in the type design of an aircraft or engine that may increase fuel venting or exhaust emissions is an “emissions change” as specified in 14 CFR 21.93, and requires further demonstration of compliance with 14 CFR part 34.

Similarly, each voluntary change in the type design of an aircraft that may increase the noise levels of that aircraft is an “acoustical change,” requiring demonstration of compliance with 14 CFR part 36.

d. Changes described in service bulletins, structural repair manuals, supplemental inspection documents, etc., with a CAA approval statement are accepted by the FAA and can be considered to be FAA-approved only under bilateral agreements. Such approval pertains to the aircraft type design only, and further FAA evaluation of installation or operational implications may be necessary.

5-5. APPROVAL OF DESIGN DATA USED TO SUPPORT REPAIRS. Repair data used to support minor repairs must be acceptable to the Administrator. Repair data used to support major repairs must be approved by the Administrator or conform to the provisions of a bilateral agreement. The FAA may accept design data to support repairs when approved by the CAA under the conditions included in a BASA IPA.

1 (and 2) APPENDIX 1

AIRCRAFT CERTIFICATION SERVICE (AIR) Director, AIR-1 Deputy Director, AIR-2 Int’l Airworthiness Programs Staff, AIR-4 Special Assistants, AIR-3, AIR-5 Production & Airworthiness Certification Division AIR-200 Aircraft Engineering Division AIR-100 Transport Airplane Directorate ANM-100 Engine & Propeller Directorate ANE-100 Small Ai rplane Directorate ACE-100 Brussels Aircraft Certification Staff AEU-100 Rotorcraft Directorate ASW-100 Airworthiness Programs Branch AFS-610 Planning & Program Management Division AIR-500 AIR Representative Asia/Pacific Region APC-100 National Resource Specialists National Resource Specialists = Located outside of Washington Headquarters Reports to AIR-4

1 APPENDIX 2. ACCOUNTABLE FAA DIRECTORATES Engine and Propeller Directorate ANE-100 Regulatory and policy responsibility for all aircraft engines, propellers, and auxiliary power units.

12 New England Executive Park Burlington, Massachusetts 01803 Telephone:(781) 238-7100 Fax:(781) 238-7199 Bilateral Countries Assigned to ANE: Belgium, Canada, Japan, Singapore, and United Kingdom Rotorcraft Directorate ASW-100 Regulatory and policy responsibility for normal and transport category rotorcraft.

2601 Meacham Blvd.

Fort Worth, TX 76137-4298 Telephone:(817) 222-5100 Fax:(817) 222-5959 Bilateral Countries Assigned to ASW: Indonesia, Italy, and South Africa

2 APPENDIX 2. ACCOUNTABLE FAA DIRECTORATES (Cont.)

Small Airplane Directorate ACE-100 Regulatory and policy responsibility for:

1. Normal, utility, and acrobatic category airplanes weighing less than 12,500 pounds and having passenger configurations of 9 seats or fewer,

2. Commuter category airplanes weighing 19,000 pounds or less, with passenger configurations of 19 seats or fewer, and

3. Primary category aircraft, gliders, airships, and hot air balloons.

DOT Building 901 Locust, Room 301 Kansas City, MO 64106-2641 Telephone:(816) 329-4100 Fax:(816) 329-4106 Bilateral Countries Assigned to ACE: Austria, Argentina, Australia, China, Czech Republic, Germany, Malaysia, New Zealand, Poland, Romania, and Switzerland Transport Airplane Directorate ANM-100 Regulatory and policy responsibility for all transport category airplanes.

1601 Lind Avenue, SW Renton, WA 98055-4056 Telephone:(425) 227-2104 Fax:(425) 227-1100 Bilateral Countries Assigned to ANM: Brazil, Denmark, Finland, France, Israel, the Netherlands, Norway, Russia, Spain, and Sweden NOTE: For countries not listed above, contact the International Airworthiness Programs Staff, AIR-4.

1 APPENDIX 3. BILATERAL AGREEMENTS RELATED TO AIRWORTHINESS (AS OF OCTOBER 2000) COUNTRY AGREEMENT TYPE APPLICATION/SCOPE OF U.S.

ACCEPTANCE 1 Argentina • BAA

• Schedule of Implementation Procedures Applies to all aeronautical products, including components 2 Australia • BAA Applies to all aeronautical products and certain components 3 Austria • BAA Applies to all aeronautical products 4 Belgium • BAA Applies to all aeronautical products and certain components 5 B r a z i l • BAA Applies to all aeronautical products and certain components 6 Canada • BASA Executive Agreement

• Implementation Procedures for Airworthiness Applies to all aeronautical products, including components 7 China • BAA

• Schedule of Implementation Procedures Applies to fixed-wing aircraft not exceeding 12,500 lbs., commuter category airplanes up to 19 passengers with a maximum certificated take-off weight of 19,000 lbs. or less, and TSO appliances 8 Czech Republic • BAA

• Operating Procedures Applies to all aeronautical products 9 Denmark • BAA Applies to all aeronautical products and certain components 10 Finland • BAA Applies to gliders and aircraft appliances 11 France • BAA Applies to all aeronautical products and certain components 12 Germany • BASA Executive Agreement

• Implementation Procedures for Airworthiness Applies to all aeronautical products and certain components 13 Indonesia • BAA

• Schedule of Implementation Procedures Applies to production oversight in Indonesia under licensing agreements with U.S.

manufacturers

2 APPENDIX 3. BILATERAL AGREEMENTS RELATED TO AIRWORTHINESS (AS OF OCTOBER 2000) (Continued) 14 Israel • BAA Applies to all aeronautical products, appliances, and components 15 Italy • BAA Applies to all aeronautical products and certain components 16 Japan • BAA Applies to all aeronautical products and certain components 17 Malaysia • BASA Executive Agreement

• Implementation Procedures for Airworthiness Applies to TSO appliances and small, all metal airplanes up to 9 passengers with a maximum certificated take-off weight of 12,500 lbs.

18 Netherlands • BAA Applies to all aeronautical products and certain components 19 New Zealand • BAA Applies to fixed-wing aircraft not exceeding 12,500 lbs. and certain components.

20 Norway • BAA Applies to all categories of civil aircraft and appliances 21 Poland • BAA Applies to certain components;

gliders; piston engines of 1,000

h.p. or less; associated propellers;

helicopters; turbine engines; and fixed-wing aircraft not exceeding 12,500 lbs.

22 Romania • BAA Applies to gliders and motorized gliders 23 Russia • BASA Executive Agreement

• Implementation Procedures for Airworthiness Applies to small, all metal airplanes up to 9 passengers with a maximum certificated take-off weight of 12,500 lbs. and to transport category cargo airplanes (both with FAA-certificated engines, propellers, and avionics.)

24 Singapore • BAA Applies to TSO appliances and components 25 South Africa • BAA Applies to all categories of civil aircraft

3 (and 4) APPENDIX 3. BILATERAL AGREEMENTS RELATED TO AIRWORTHINESS (AS OF OCTOBER 2000) (Continued) 26 Spain • BAA Applies to all categories of civil aircraft and appliances 27 Sweden • BAA Applies to all aeronautical products and certain components 28 Switzerland • BAA Applies to all aeronautical products and certain components 29 United Kingdom • BAA Applies to all aeronautical products and certain components