ARSA Training Resource

On-Demand Training Session – Major/Minor


Classifying repairs and alterations as major or minor has been a source of confusion to the Federal Aviation Administration (FAA), and therefore the aviation industry, for many years. In fact, the problem dates back to 1931, when the first regulation governing this activity was issued.

The Department of Commerce, regulated aviation under its Aeronautics Branch, issued Aeronautics Bulletin No. 7-H specifying that a “licensed aircraft or a major component thereof” that “has been damaged to such an extent that it constitutes a major repair in the judgment of the Department of Commerce inspector” warranted heightened requirements under the regulations. While certificated repair stations were able to make major repairs “in accordance with the original design on aircraft of the class or classes of structure specified in the terms of its certificate,” any other instances of major repair required approval of technical data and inspection by the agency’s representative.

By the end of the decade, the Civil Aeronautics Authority was created as an independent agency to fulfill the duties of the Aeronautics Branch. The 1931 regulation transformed into 14 CFR part 18, the predecessor to part 43. In 1940, part 18 addressed both major and minor repairs, but not major or minor alterations.

In 1942, definitions of major and minor alterations appeared; the regulation defined minor alterations in detail and classified major alterations as “all alterations not within the definition of minor alterations.” Fast forwarding to the current definitions in 14 CFR § 1.1, the approach is opposite: major repairs and alterations are defined in detail whereas minor repairs and alterations are described as “other than…major.”

While this one-or-the-other approach may seem simplistic, it makes sense: the regulatory requirements for major and minor are different. Thus, from a practical standpoint there cannot be any crossover.

So what else do the current regulations have to say about major versus minor repairs and alterations? It is best to start with the difference between a repair and an alteration. Since 14 CFR § 1.1 does not define either term, we look to part 14 CFR § 43.13, which requires an article be returned “to its original or properly altered condition.” Therefore, a repair is an action that returns the article to its “original” condition, while an alteration creates a “properly altered” condition, or a “new original” (airworthy) condition.

After determining the activity is a repair or an alteration (or, indeed, has aspects of both), the next query is whether the action will be major or minor. Section § 1.1 gives the parameters for an evaluation.

For a repair, the first consideration is whether it is “improperly done.” There are two components to that evaluation: (1) What would happen if the action is improperly designed, and (2) What would happen if the repair is improperly implemented.

With respect to an alteration, however, the first consideration is whether the planned action is “listed in the [product’s] specification,” a definition that is elusive. There is no help in any regulations or FAA guidance materials, and there are several ways the term can be interpreted. One way to interpret product specification is as the configurations available from the type design or supplemental type certificate; if it is contained in the type design, the installation or change to a product is not major. On the other hand, the agency takes the position that changes to an existing product that impact airworthiness characteristics are major alterations even if the type certificate or type design includes all potential configurations and service bulletins are available to change from one to the other. In other words, the evaluation applies to the product being worked on, no matter what is available or possible under the type design or from a design approval holder, e.g., the type certificate holder.

The last evaluations are the same for both major repair and major alteration. First, whether the action can be done “according to accepted practices or…by elementary operations.” Accepted practices include standard procedures from or by the government (FAA, Department of Defense, etc.), the design or production approval holder, or an industry source.

What is elementary for one mechanic or repair station may not be elementary for another. To determine whether the operation is elementary, make sure it is in writing and repeatable, and whether it requires special education or training to accomplish in a standard (repeatable) manner. Even if it is in writing and repeatable, the action could be considered major if the technician performing the required methods, techniques and practices needs special training.

Finally, there is the consideration of whether the action (again, either repair or alteration) “might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness.” That determination must consider the measurable impact on the article, the system, and the product under the applicable airworthiness standards.

The purpose of the entire evaluation is to eliminate the determination of “major” so the action defaults to minor under the regulations. The technical and engineering data required to make the determination will always be used to substantiate the action taken. Indeed, that data can be “approved” if it is determined the action is major. If the work performed is questioned by the agency, documentation of the determination will help ensure the result was airworthy, reducing anxiety and therefore the possibility of legal enforcement.

Ultimately, there are three reasons why you should care whether something is major or minor: (1) The recordkeeping requirements differ, (2) The persons who can approve the work for return to service differ, and (3) The substantiating data supporting a major action must be approved by the Administrator.

Recordkeeping for major repairs and alterations requires more paperwork; Appendix B to part 43 requires major repairs or alterations to be documented on a Form 337. If the major repair is performed by a repair station “in accordance with a manual or specifications acceptable to the Administrator,” a work order with specified language will suffice; however, all major alterations require a Form 337 (unless another document is required by an air carrier or commercial operator under parts 121 or 135).

As for approving work for return to service, 14 CFR § 43.9 allows the person performing minor repairs and alterations to approve that work for return to service. However, if the repair or alteration is major, only an air carrier, appropriately rated repair station, or a mechanic with an inspection authorization may issue the approval for return to service.

Finally, there are requirements in parts 65, 121, 135, and 145 that major repairs and major alterations be performed in accordance with FAA-approved technical data, which should be referenced in the maintenance record.

The latest ARSA news regarding Major/Minor is below; click here for archived content. For more information, click here to access the on-demand recording of Sarah MacLeod’s webinar Major Pain Over a Minor Issue.

Timeline of ARSA Major/Minor Action:

Jun 9, 2013 ARSA submitted comments to FAA draft order 8300.X providing guidance on requirements for approval of technical data associated with major repairs or alterations

Dec. 7, 2011 ARSA sent a letter requesting that the FAA reconsider its position on the applicability of “automatically defined” major repairs listed in 14 CFR part 43, Appendix A.

June 13, 2007 TCCA responds to ARSA’s April 9 request in a formal confirmation of policy.

May 15, 2007 ARSA sent a letter requesting the FAA withdraw or revise a controversial memorandum that was at odd with the regulations relating to major and minor repairs and alterations. The FAA rescinded the memo shortly thereafter.

May 1, 2007 ARSA sent a letter requesting that the FAA create comprehensive guidance for repair stations that develop their own maintenance processes (repair specifications). The FAA adopted many of ARSA’s suggestions in Order 8300.14 (which has since been cancelled). Our draft guidance still follows the regulations and ensures a repair station creates the data to support any action it may wish to take.

April 9, 2007 ARSA sent a letter requesting that Transport Canada, Civil Aviation Directorate (TCCA) adopt a uniform policy for recording major repairs performed in the U.S. on Canadian aeronautical products.

Major/Minor Repairs Q&A

FAA Clarifies Position on EASA Form 1 Triple Release

In a May 23 letter to ARSA, the FAA clarified its position on the use of European Union Aviation Safety Agency (EASA) Form 1 as a triple release by EU…Read More

AMT Day 2024 – Celebrating Charlie

Charles Taylor, the Wright Brothers’ mechanic and father of aviation maintenance, was born on May 24, 1868. Now – 156 years later – we celebrate him through continued commitment to…Read More

ARSA Pushes FAA Bill Into Law

On May 7, ARSA delivered a letter to House and Senate leadership strongly supporting the FAA reauthorization bill unveiled April 29. “At a time when the national airspace system (NAS)…Read More

Quick Question – Inventory Costs for EASA Compliance

Since the FAA withdrew its of acceptance of ARSA’s E100 form in 2022, ARSA has been engaged with American and European regulators trying to address major misunderstandings related to parts…Read More

Further Clarifying Part 145 using “Current Data” Proposal

On May 1, ARSA and three other trade associations commented on the FAA’s notice of proposed rulemaking addressing “miscellaneous maintenance-related updates.” The NPRM would remove the requirement from § 145.109…Read More