AC 43-210A

Historical

Advisory circular · Standardized Procedures for Obtaining Approval of Data Used in the Performance of Major Repairs and Major Alterations

A newer version is currentThis is a historical version. AC 43-210A CHG 2 is the version in force, approved June 23, 2026.
Approved
August 17, 2016
Last reviewed
June 18, 2024
Cancels
AC43-210
Cancelled by
AC43-210A CHG 1
Family
AC 43-210 · 5 versions
Revision
A
14 CFR parts
43, 65, 121, 135, 145
Cited by
3 ADs

Guidance, not mandatory unless a rule or AD requires it. DRS record last changed November 21, 2025.

U.S. Department of Transportation Federal Aviation Administration Advisory Circular Subject: Standardized Procedures for Obtaining Approval of Data Used in the Performance of Major Repairs and Major Alterations Date: 8/17/16 Initiated by: AFS-300 AC No: 43-210A Change:

This advisory circular (AC) describes a standardized procedure for requesting approval of technical data associated with major repairs/major alterations. This AC also provides information that can help determine if a proposed repair/alteration requires approved data, guidance and standardized procedures for obtaining field approval (or approval by other means) of data, and instructions for completing the field approval checklist. This AC is not mandatory and does not constitute a regulation. This AC describes an acceptable means, but not the only means, to obtain approved data for a major repair or major alteration. However, if you—whether you’re an aircraft owner, operator, or Aviation Maintenance Technician (AMT), collectively termed an applicant—use the means described in the AC, you must follow it in all important respects.

ORIGINAL SIGNED by /s/ John Barbagallo Deputy Director, Flight Standards Service

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CONTENTS Paragraph Page

1 Introduction1

1.1 Purpose1

1.2 Applicability1

1.3 Cancellation1

1.4 Regulatory Basis1

1.5 Repair and Alteration Classification1

1.6 Responsibility for Obtaining Data2

1.7 General Information2

2 Data2

2.1 Definition of Data as it Relates to a Repair or Alteration2

2.2 Classification of Technical Data2

3 Field Approval Process And Data Approval6

3.1 General Information6

3.2 Conduct Research6

3.3 Evaluate the Data8

3.4 Perform Repair or Alteration12

4 Flight Manual Supplements15

4.1 General Information15

4.2 Aircraft Flight Manuals15

4.3 Manual Supplements15

4.4 Format and Content15

4.5 Supplement Information Approval16

4.6 Aircraft Certification Office Approval Process17

4.7 Additional AFMS Considerations17

5 Maintenance Information18

5.1 Purpose of Maintenance Information for a Major Repair or Major Alteration18

5.2 Benefits of Providing Maintenance Information for a Major Repair or Major

Alteration18

5.3 Maintenance Information as Part of the Major Repair or Major Alteration Data

Package18

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5.4 Maintenance Information Under the Civil Air Regulations (CAR)19

5.5 Maintenance Information Development19

5.6 Maintenance Information Content19

6 Administrative Matters22

6.1 Acronyms22

6.2 Related FAA Orders and Advisory Circulars23

6.3 Obtaining Copies of Referenced Documents and This AC24

Appendix A. Instructions for Completing the Field Approval ChecklistA-1

Appendix B. Instructions for Completing the Compliance ChecklistB-1

List of Figures Figure 2-1. Possible Resources for Approved Data Relevant to Major Repairs or

Major Alterations5

Figure 3-1. Field Approval Process13

Figure 3-2. Determination of Major or Minor Alteration or Repair14

Figure 5-1. Major Repair or Major Alteration Maintenance Information Checklist21

Figure A-1. Field Approval ChecklistA-3

Figure B-1. Compliance Checklist FormatB-1

1 1 INTRODUCTION.

1.1 Purpose. This advisory circular (AC) describes a standardized procedure for requesting approval of technical data associated with major repairs/major alterations. This AC also provides:

1. Information that can help determine if a proposed repair/alteration requires approved data;

2. Guidance and standardized procedures for obtaining field approval, or approval by other means, of data; and

3. Instructions for completing the field approval checklist (see Appendix A).

1.2 Applicability. This AC applies to applicants who request data approval for a major repair or major alteration.

1.3 Cancellation. This AC cancels AC 43-210, Standardized Procedures for Requesting Field Approval of Data, Major Alterations, and Repairs, dated February 17, 2004.

1.4 Regulatory Basis. Title 14 of the Code of Federal Regulations (14 CFR) part 43, § 43.7 specifies persons authorized to approve an aircraft or aircraft component for return to service after maintenance, preventative maintenance, rebuilding, or alteration. For major repairs or major alterations the work must be done in accordance with technical data approved by the Administrator. The following CFR references require the use of this data:

1. Title 14 CFR part 43, §§ 43.7(d) and 43.17(e)(2);

2. Title 14 CFR part 65, § 65.95(a)(1);

3. Title 14 CFR part 121, § 121.379(b);

4. Title 14 CFR part 135, § 135.437(b); and

5. Title 14 CFR part 145, § 145.201(c)(2).

Title 14 CFR part 1, § 1.1 defines major repairs and major alterations. In addition, part 43 appendix A, paragraph (a) further defines what constitutes a major alteration. In a similar manner, part 43 appendix A, paragraph (b) further defines what constitutes a major repair. A minor alteration is an alteration that is not major. Likewise, a minor repair is one that is not a major repair.

1.5 Repair and Alteration Classification. Only those persons with § 43.7 authorization may approve an aircraft, airframe, engine, propeller, appliance, or component part for return to service after the performance of a repair or alteration. You must perform major repairs and major alterations using technical data approved by the Administrator. You may perform minor repairs and alterations using technical data acceptable to the Administrator. This AC includes flowcharts (Figures 3-1, Field Approval Process, and 3-2, Determination of Major or Minor Alteration or Repair) to help classify a repair/alteration.

2 For assistance, you may use the Major Repair and Alteration Data Approval Job Aid at http://fsims.faa.gov/Wdocs/Other/Major_Repair_Alteration_Job-Aid%20R5.pdf. The job aid lists types of alterations and how applicants typically classify them.

1.6 Responsibility for Obtaining Data. It is the responsibility of the person intending on performing the major repair/major alteration to obtain, organize, and submit data to the approving authority for review and approval.

1.7 General Information. For the purpose of this order, the use of the term “ASI” includes Designated Airworthiness Representative (DAR) Function Code 51 when performing work in accordance with the current edition of Federal Aviation Administration (FAA) Order 8100.17, Field Approval Delegation Handbook. Also for the purposes of this guidance, Aircraft Flight Manual Supplement (AFMS) includes Rotorcraft Flight Manual Supplement (RFMS) and Supplemental Aircraft Flight Manual (SAFM).

2 DATA.

2.1 Definition of Data as it Relates to a Repair or Alteration. In its broadest sense, data is recorded information. Data supporting a repair or alteration consists of drawings and specifications, including a list of drawings and specifications, which define configuration and design features of a particular article, repair, or alteration. Data may be classified relative to its type or its approval status.

2.2 Classification of Technical Data.

2.2.1 Types of Data.

2.2.1.1 Descriptive Data. Descriptive data describes the design of the repair or alteration. It should include reference to installation methods, materials, fabrication processes, dimensions, and tolerances. It may also include intended function and how the alteration is appropriate to the aircraft.

Descriptive data, typically includes:

1. The drawings (or equivalent) and specifications necessary to define the configuration and the design features;

Note: We accept sketches, photos, or pictures as descriptive data when it is appropriate, such as for certain one-time approvals.

2. Information on dimensions, materials, and processes;

3. Airworthiness limitations, if applicable; and

4. Documents required by the airworthiness requirements such as instructions for continued airworthiness (ICA) and airplane or rotorcraft flight manuals.

2.2.1.2 Substantiating Data. Substantiating data shows that the design complies with the applicable regulations and that all appropriate technical considerations have been addressed. Examples of substantiating data can be: test results,

3 computations, and other information necessary to show that descriptive data meets the applicable requirements. Such substantiating data, when approved forms the basis of declaring conformity to the type design or applicable airworthiness standards.

2.2.2 Approval Status.

2.2.2.1 Approved Data. Approved data is data approved by the FAA. The term “approved” is based on § 1.1, which states, “Approved, unless used with reference to another person, means approved by the FAA or any person to whom the FAA has delegated its authority in the matter concerned, or approved under the provisions of a bilateral agreement between the United States and a foreign country or jurisdiction.” For the FAA aviation safety inspector (ASI), “approved” or “approved by” means the item (e.g., data;

methods, techniques, and practices; manual contents; tools; materials;

equipment) is required to be and has been reviewed and formally approved by the FAA (or appropriate Civil Aviation Authority (CAA)). Approvals are granted only by letter, by a stamp of approval, by the issuance of operations specifications (OpSpecs), or by other official means. All data used to substantiate a major repair or major alteration, regardless of the source, must be approved before being used.

2.2.2.2 Acceptable Data.

2.2.2.2.1 Acceptable data means data acceptable to the FAA. The terms “acceptable to the Administrator” and “acceptable to the FAA” appear numerous times in the maintenance regulations. They refer to any item addressed in the regulation

(e.g., data; methods, techniques, and practices; manual contents; tools;

materials; equipment; etc.) that must meet regulatory standards. If the regulation requires only that an item must be “acceptable to,” it does not necessarily follow that the FAA requires the item to have specific FAA review and acceptance before it may be used. A person making a determination of whether an item is “acceptable to” the agency must ensure the item addresses specific applicable section(s) of the regulations.

2.2.2.2.2 Items required by regulation to be “acceptable to” the FAA or to the Administrator (unless otherwise required by regulation to be approved) do not necessarily require FAA review and acceptance prior to a person using the item. A person using an item that must be acceptable to the FAA should be able to demonstrate that the item meets all applicable regulatory requirements.

If, however, upon subsequent review of the item, the FAA believes the item is not acceptable, the agency has the burden of demonstrating its unacceptability in any related enforcement matter. In any event, if an ASI finds an item unacceptable to the FAA, the ASI must immediately inform the maintenance provider/certificate holder, in writing, of the potential noncompliance and request compliance.

2.2.3 Previously Approved Data. This term refers to data that was approved for a specific purpose, such as a Supplemental Type Certificate (STC) or major alteration on an aircraft, powerplant, propeller, or appliance. All previously approved data has to be applicable to the requested major repair or major alteration. All differences, deviations, inclusions, and exclusions between the original use of the data and the current one must be considered before the data can be approved for use. Figure 2-1, Possible Resources for Approved Data Relevant to Major Repairs or Major Alterations, lists typical sources by which you can obtain previously approved data. Not all of this data may be readily available. It is the applicant’s responsibility to review all data that is available. You should consider the following items when evaluating previously approved data:

2.2.3.1 Product Certification Basis. If the certification basis applicable to the product intended to be altered or repaired is different from the basis the previously approved data was developed for, you must make a comparison of the two and the differences addressed in making a determination of applicability for use of the previously approved data.

2.2.3.2 Special Conditions. If special conditions are required to show compliance, representative data must be specifically approved for the product or appliance intended for alteration or repair.

2.2.3.3 Equivalent Level of Safety (ELOS) Findings. If ELOS are used to show compliance, the underlying data must be specifically approved for the specific product or appliance intended for alteration.

2.2.3.4 Exemptions. If data was developed and approved for a product design based on an exemption to an airworthiness standard, you must consider the exemption impact and any deviation which may have been granted to the approved product or appliance. Such exemption or deviation may require independent approval by the FAA or an appropriately authorized Designated Engineering Representative (DER) or Organization Designation Authorization (ODA).

2.2.3.5 Applicability. You must review the data to determine applicability to intended use. If any data is not appropriate to the intended repair or alteration, it should not be referenced as supporting data.

5 Figure 2-1. Possible Resources for Approved Data Relevant to Major Repairs or Major Alterations Type Certificate Data Sheet (TCDS). Refer to the current edition of FAA Order 8620.2, Applicability and Enforcement of Manufacturer’s Data, for guidance.

Repair data from the current edition of AC 43.13-1, Acceptable Methods, Techniques, and Practices— Aircraft Inspection and Repair, as approved data for nonpressurized areas of civil aircraft, and the AC chapter, page, and paragraph listed in block 8 of FAA Form 337, Major Repair & Alteration (Airframe, Powerplant, Propeller, or Appliance), when the applicant has determined that it is:

• Appropriate to the product that is intended to be repaired;

• Directly applicable to the repair being made; and

• Not contrary to the airframe, engine, propeller, or appliance manufacturers’ repair data or instructions.

Alteration data from the current edition of AC 43.13-2, Acceptable Methods, Techniques, and Practices—Aircraft Alterations, as approved data for major alterations for nonpressurized areas of civil aircraft when the AC chapter, page, and paragraph are listed in block 8 of FAA Form 337, when the user has determined that it is:

• Appropriate to the product intended to be altered;

• Directly applicable to the alteration being made; and

• Not contrary to the airframe, engine, propeller, product, or appliance manufacturers’ data.

Airworthiness Directives (AD).

Appliance manufacturer’s manuals or instructions, unless specifically not approved by be used as approved data for major repairs.

the FAA, may Data describing an article used in an FAA-approved alteration under a parts manufacturer approval (PMA).

Designated Engineering Representative (DER)-approved data, including repair specifications, within limitations on the DER’s authorization.

Organization Designation Authorization (ODA)-approved data, within limitations in the ODA holder’s procedures manual.

FAA-approved portions of structural repair manuals (SRM).

FAA-approved service bulletins (SB) and service letters (SL) or similar documents as documented the current edition of AC 20-77, Use of Manufacturers’ Maintenance Manuals.

in Foreign bulletins, for use on U.S.-certificated foreign-designed aircraft, when approved by the foreign authority within the provisions of a bilateral agreement with the United States or as listed in TCDS notes.

Original aircraft manufacturer’s service and repair data in accordance with current regulations, for major repairs on elements of nonpressurized airplanes, 12,500 pounds or less maximum certificated takeoff weight provided the person intending to perform such repair determines that:

• Data is appropriate and applicable for the specific make, model, and type of product being repaired; and

• The repair does not deviate from the manufacturer’s methods, techniques, and practices.

United States Department of Commerce, Form ACA-337 dated prior to October 1, 1955, provided the data is appropriate, directly applicable, and not contrary to regulatory requirements.

Supplemental Type Certificate (STC) data may substantiate a major alteration on a different aircraft, provided such alteration is applicable to specifically listed make, model, and type appropriate to the certification basis and applicable amendments.

6 3 FIELD APPROVAL PROCESS AND DATA APPROVAL.

3.1 General Information. An applicant must use approved technical data to accomplish a major alteration or repair on a product and approve the product for return to service. An applicant must perform three major steps when performing a major repair or major alteration: (1) conduct research, (2) evaluate the data, and (3) perform the repair or alteration.

Note: You should not start work until all data is approved. Inspectors may not be able to complete the approval as requested. If an applicant starts work before the approval is finalized, that work may not conform to the repair or alteration as approved.

3.2 Conduct Research.

3.2.1 Plan the Repair or Alteration. You should review the repair or alteration to be performed to determine the effects to the proposed change as to whether certain aspects of the alteration or repair can be accomplished using acceptable data and/or whether other aspects of the alteration or repair require approved data. You must assure that the performance of the intended alteration or repair meets the applicable airworthiness standards and the product can be restored to its original or proper condition and is safe for operation. You must determine the certification basis of the product, including all applicable amendments, to ascertain if the alteration or repair can be accomplished using the field approval process admissible as a minor change to the type design. Or if the intended alteration or repair is significant enough to warrant seeking an STC, since a determination of such intended repair or alteration, when performed, results in a major change to the type design. Typical data may include analysis, drawings, photographs, specifications, or test data as required.

Note: Some aspects of the intended alteration or repair of a product may be performed using the field approval process. Whereas, other aspects may be determined significant such that one or more certificated properties of the product are exceeded, thus requiring a new certification basis be established.

3.2.2 Determine the Repair or Alteration Classification. Determine if the repair/alteration is a minor change in type design (as defined in 14 CFR part 21, § 21.93) to the product’s type design; and if so, is it a major or a minor repair/alteration. To determine if a repair/alteration is major or minor, refer to part 43 appendix A. Figure 3-2, Determination of Major or Minor Alteration or Repair, is a flowchart of the field approval evaluation process based on part 43 appendix A.

3.2.2.1 Minor Repair or Minor Alteration. If you are properly authorized, you may perform a minor repair/alteration using acceptable data, and without approved data. You may document the alteration or repair in the product’s logbook per § 43.9 indicating return-to-service.

3.2.2.2 Major Repair or Major Alteration. You must perform a major repair or major alteration using approved data. If some substantiating data is not obtainable or cannot be approved by FAA designees, or by the ASI, then such data needs to be developed for those aspects of the major repair or major alteration intended to be performed and the request for such data approval be elevated to the appropriate Aircraft Certification Office (ACO) for approval.

Your ASI can assist in such elevation and should assure timely review and approval by the ACO. After such data is reviewed and approved by the ACO, then the alteration or repair may be accomplished, using such substantiating data, as applicable. The field approval process is not available for all major repairs/major alterations, and some aircraft are not eligible for field approvals.

Major repairs and major alterations that have all the necessary DER or ODA-approved technical data do not require further approval. See paragraphs 3.3.2 and 3.3.3 in this AC for more information.

Note: Aircraft operating under part 121 are eligible for field approvals under certain circumstances. If you are a part 121 operator, check with the ASI before beginning a repair or alteration. Persons holding delegation by the Administrator are not authorized to issue field approvals for aircraft operated by air carriers certificated under part 121.

3.2.2.3 Major Changes to Type Design. Major repairs/major alterations that are major changes to type design require an STC or an amended type certificate (TC). The field approval process is not available in these cases. The current edition of Advisory Circular (AC) 21-40, Guide for Obtaining a Supplemental Type Certificate, details the STC application process for a broad audience, while the current edition of FAA Order 8110.4, Type Certification, provides that same detail for ASIs. Personnel may also find useful the Major Repair and Alteration Data Approval Job Aid associated with FAA Order 8300.16, Major Repair and Alteration Data Approval. This job aid lists alterations governed by Order 8300.16 and alterations that should be processed as major changes in the approved type design.

3.2.3 Gather Data. Gather and organize data describing and substantiating the proposed repair/alteration. Review paragraph 2 for data types you might use.

3.2.4 Prepare the Data Package. To organize project data and standardize the field approval process, we recommend using a data package. A typical data package might include the following items:

1. Field approval checklist;

2. Copies of any substantiating data;

3. FAA Form 337, Major Repair or Alteration (Airframe, Powerplant, Propeller, or Appliance);

4. Compliance checklist;

5. Maintenance information; and

6. Draft Proposed AFMS or RFMS.

Note: Review and approval of an AFMS, RFMS, or SAFM is independent of the review and acceptance of approved data (or approval of technical data). The approval is indicated on the AFMS, RFMS, or SAFM, so you don’t need a separate FAA Form 337. See paragraph 4 of this AC for further AFMS information.

3.2.4.1 Complete the Field Approval Checklist (recommended). The checklist and instructions in Appendix B can be used to organize data and information before requesting a field approval. It is a tool to ensure your submission is complete.

3.2.4.2 Substantiate Applicable Requirements. Indicate the specific applicable airworthiness requirements to show compliance, including the amendment level of the regulation and other requirements, except that you should not use general references, such as “part 25.” As shown in Appendix B, you may reference a compliance checklist, specific to descriptive data instead of listing regulatory requirements.

3.2.4.3 Complete FAA Form 337. Complete FAA Form 337, except for dates and signatures in blocks 6 and 7. You should enter dated signatures after completing the repair/alteration and inspecting for conformance. The current edition of AC 43.9-1, Instructions for Completion of FAA Form 337, provides guidance on how to complete this form.

3.3 Evaluate the Data. Review the data to determine (1) if the package is complete and inclusive, and (2) if applicable data has been approved. There are several methods to obtain all the approved data. We sometimes use the field approval process, with an authorized ASI or other delegated authority, to approve technical data. Another alternative is approval of all the data by a DER or ODA. In some cases, you might need multiple DERs when the repair/alteration deals with several disciplines, such as systems and structures.

3.3.1 The Field Approval Process. Field approvals are a method by which the FAA approves technical data for a major repair/major alteration on a single aircraft, and operational approval by reviewing and approving AFMS (RFMS or SAFM). A field approval may constitute an approval for the alteration or repair, and is a one-time approval for the product or appliance to which it applies. The overall process is illustrated in Figure 3-1, Field Approval Process, and is explained in paragraphs 3.3.1.1 through 3.3.1.3 below.

Field approvals are a method by which we approve technical data for a major repair/major alteration on a single aircraft.

A field approval may require engineering assistance or coordination with an ACO. You may use the field approval process to obtain approval of acceptable data in certain cases.

9 Note 1: The information and process steps are provided in Figure 3-1 in a specific order to show a logical progression through the repair/alteration. We’re not implying that one step must follow another in the order presented. Several actions may take place concurrently or in a different order. The goal is that you address all necessary concerns and regulatory considerations when performing a major repair/major alteration.

Note 2: The paragraph numbers next to blocks in the figure correspond to associated paragraph numbers in this order, which provide information in more detail.

3.3.1.1 Contact the FAA ASI. Contact a local FAA office and speak with an ASI who has field approval authority. Discuss the repair or alteration with the ASI and determine if you need to meet to review the request. Be as specific as possible about the needs, and especially about the schedule. In some cases you may contact DARs delegated with the authority to perform Function Code 51, who are now authorized to approve certain data in support of a major repair or major alteration by entering and signing the appropriate data approval statement in block 3 of FAA Form 337.

3.3.1.2 Provide Data Package to the ASI. Send a complete data package to the ASI.

Using the checklist in Appendix B is one way to organize data and may help prevent omissions.

3.3.1.3 ASI Review Procedures.

3.3.1.3.1 When the ASI receives the package, the ASI will review it to determine if the field approval request is appropriate.

1. Minor alterations/repairs do not require approved data. ASIs who deny data approval requests for alterations or repairs that do not require approval must explain to the applicant the reason for the denial and, if requested, provide a written explanation in letter or electronic form.

2. The Major Repair and Alteration Data Approval Job Aid describes repairs and alterations within the scope of a field approval. If the ASI determines that the alteration is not a major change but is outside of the field approval authority, the ASI should refer the applicant to utilize an appropriately authorized designee. If the ASI determines that the alteration is a major change in type design and requires an STC, and if the applicant is the design approval holder (DAH), the ASI should inform the applicant to apply for an STC or amended TC.

3. The ASI should examine the data to see if it has been approved. If all the required data is approved, then further approval is not required. If any required technical data is not approved, then you