Chapter 12. Publications, Forms, & Records

§43.5 Approval for return to service after maintenance, preventive maintenance, rebuilding, or alteration

Returning an aircraft component of an aircraft to service after maintenance, preventive maintenance, rebuilding or alteration must be done by creating an appropriate maintenance record entry as required by either §43.9 or 43.11. This may include the use of FAA Form 337, Major Repair and Alteration, if the maintenance action was a major repair or a major alteration.

Whenever a maintenance action is being planned, it is critical that the technician understands exactly:

  • What he/she is going to do,
  • How that work is classified by the FAA, and
  • What type of documentation will be required to support this activity.

The first question to consider is “Is this a repair or an alteration?" This should be a relatively simply decision since a repair basically returns the aircraft to its previous or unaltered condition (i.e., replacing magnetos, an exhaust system, tires, or brakes). Even replacing an entire engine (although it is a big job) is still a repair if it is the one properly specified for that aircraft. An alteration, on the other hand, always changes or modifies the aircraft from its previous state (i.e., installing winglets, new avionics, or an engine that is NOT listed in the aircraft TCDS). Please refer to part 1 and part 43, appendix A, for additional clarification and examples.

The second question to consider is whether or not the work that will be performed constitutes a major or a minor maintenance action. A “major" action is typically one that might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness, and that are not done according to accepted practices or cannot be done by elementary operations. (The reader is again requested to refer to part 1 and part 43, appendix A, for additional clarification and examples.) This is a much more complex question, but it is extremely important as it drives the final question concerning the substantiating documentation.

The third question deals with the type of documentation required to substantiate the work performed. Minor repairs and alterations need only to refer to “acceptable" data, such as manufacturers’ maintenance manuals or AC 43.13-1, the maintenance action can simply be recorded in the maintenance record as a logbook entry. Major repairs and alterations require “approved data" Some examples of approved data are: AD Notes, STCs, TCDS’s, DAS specific authorizations, DER specific delegations, and FAA-approved manufacturer Service Bulletins.

Sometimes the repair or alteration being performed does not have previously approved data. In that case the technician may request that the FAA accomplish a “Field Approval." In this procedure, the technician completes the front side of Form 337 through block 6 (leaving block 3 open for later FAA approval) and then indicates in block 8 on the back what work is to be done, and what the substantiating reference data is. Form 337 is then submitted to the local FAA FSDO office for review and approval by an ASI. If necessary, this ASI may seek input from other ASIs or FAA specialists to assist in the review of the data. If the data is found to comply with FAA regulations, the ASI will enter one of the following statements in block 3, depending on whether the ASI has performed a review of the data only, or has physically inspected the aircraft:

  • “The technical data identified herein has been found to comply with applicable airworthiness requirements and is hereby approved for use only on the above described aircraft, subject to conformity inspection by a person authorized in part 43, section 43.7."


  • “The alteration or repair identified herein complies with the applicable airworthiness requirements and is approved for use only on the above described aircraft, subject to conformity inspection by a person authorized in part 43, section 43.7."

§43.7 Persons authorized to approve aircraft, airframes, aircraft engines, propellers, appliances, or component parts for return to service after maintenance, preventive maintenance, rebuilding, or alteration

There are seven different persons listed in this section who may sign return to service (RTS) documentation:

  • Certified mechanic or holder of an inspection authorization.
  • Holder of a repair station certificate.
  • Manufacturer.
  • Holder of an air carrier certificate.
  • Certificated private pilot.
  • Repairman certificated with a maintenance rating for light sport aircraft only.
  • Certificated sport pilot for preventive maintenance on an aircraft owned and or operated by him or her.

Note that although a certificated repairman is authorized to work on a product undergoing maintenance, preventive maintenance, rebuilding, or alterations (refer to §43.3), he or she is not authorized to approve that product for return to service. He or she must make the appropriate maintenance record entry per the requirements of §43.9 or 43.11.

§43.9 Content, form and disposition of maintenance, preventive maintenance, rebuilding, and alteration records (except inspections performed in accordance with parts 91 and 125, and §§135.411(a)(1) and 135.419 of this chapter).

The first observation is that this section specifically excludes inspection entries (those are covered in §43.11). This section deals exclusively with maintenance record entries.

The next observation should be that the list of maintenance actions includes “preventive maintenance." As stated in the explanation of §43.3, a certificated pilot is authorized to perform preventive maintenance on the aircraft he or she owns or operates. Therefore, remember that the pilot must make a record entry of the preventive maintenance he or she has accomplished.

There are three distinct issues to be addressed in the maintenance entry, and they answer the questions of “what? when? and who?"

What — a description of the work performed.

When — the date the work was completed.

Who — the name of the person who did the work if other than the person who approves the Return to Service

— the signature, certificate number, and type of certificate of the person who is approving the work for return to service.

Note: Frequently, logbooks have a statement entered that ends something like this: “ … and is hereby returned to service. Joe Fixer A&P, Certificate #123456789." As this section of the regulation currently reads, that part of the record entry is not required, since §43.9 clearly states that “the signature constitutes the approval for return to service only for the work performed," which also leads to another point. The technician is only signing off the work he or she has done. We will see later in the explanation of §43.11 that an inspection writeup usually carries a broader scope of responsibility. This section is very clear that the entry completed in accordance with this section only holds the technician responsible for the service maintenance action he or she entered.

If the maintenance accomplished was a major repair or alteration (both of which require supporting approved data), the work must be documented on FAA Form 337. If the maintenance action was a major repair and it was done by a certificated repair station, a signed copy of the completed customer work order accompanied by a signed maintenance release may be used in lieu of the FAA Form 337.

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