4.5 Regulations, Forms, Records, and Publications

The Part 43 Framework

Regulations, records, and forms turn mechanical work into legal maintenance. 14 CFR Part 43 governs maintenance, preventive maintenance, rebuilding, and alteration; Part 65 sets mechanic certification and privileges; Part 91 assigns the owner/operator the duty to keep the aircraft airworthy.

Part 1 defines the key terms: maintenance (inspection, overhaul, repair, preservation, and parts replacement), preventive maintenance (simple/minor operations and small standard-part replacement that a certificated pilot may perform on owner-operated aircraft, listed in Part 43 Appendix A), and major repair and major alteration (any repair or alteration that is not major is minor).

Major vs. minor is a frequent question. A major repair or major alteration is one that, if done improperly, appreciably affects weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other airworthiness qualities, or that is not done by elementary operations or by accepted practices. Major work requires approved data and, in addition to the maintenance record entry, is recorded on FAA Form 337, executed at least in duplicate: a signed copy to the aircraft owner and a copy to the FAA Aircraft Registration Branch in Oklahoma City within 48 hours after approval for return to service (for a major repair done to an acceptable manual or specifications, a repair station may instead use the customer's work order and a maintenance release); minor work may use acceptable data.

Distinguish approved data for applicable major work from acceptable methods, techniques, and practices for other maintenance. FAA AC 43.13-1B/2B and manufacturer service information must be applicable to the task; neither is a blanket authorization to depart from the aircraft’s approved configuration.

Under Part 65, a certificated mechanic with the appropriate rating may perform and approve for return to service the maintenance and minor alterations within the privileges of the rating, and may perform the 100-hour inspection within the privileges of the airframe or powerplant rating. An annual inspection requires the appropriate additional inspection authority, such as an Inspection Authorization (IA) for a mechanic. Recent-experience requirements still apply. Ordinary maintenance is documented under 14 CFR 43.9; required inspection entries follow 43.11.

Record Entries: 43.9 vs. 43.11

The two record rules are constantly confused, so learn the split:

A 43.9 maintenance entry needs the description of work performed (or a reference to data acceptable to the Administrator), the date of completion, the name of the person who did the work (if different from the approver), and the signature, certificate number, and kind of certificate of the person approving for return to service. A 43.11 inspection entry must also state the inspection type and extent, the date, and the aircraft total time in service, followed by either a statement that the aircraft was found airworthy or a list of discrepancies and unairworthy items.

Inspections and Return to Service

Annual and 100-hour inspections share the same scope (Part 43 Appendix D), but differ in who and when:

Approval for return to service is governed by 43.7 (who may approve) and 91.407 (the owner may not operate until the required 43.9 or 43.11 entry has been made). 14 CFR 43.13 is the performance rule: maintenance must use methods, techniques, and practices acceptable to the Administrator (commonly the manufacturer's manual or AC 43.13-1B/2B), with tools and equipment to ensure the work meets approved standards.

Airworthiness Directives and Publications

An Airworthiness Directive (AD) is a mandatory FAA regulation issued to correct an unsafe condition; the mechanic must determine applicability from the AD's own applicability section (the affected models and serial numbers, plus any installed part numbers or modifications), searching ADs for the aircraft, engines, propeller, and installed appliances and confirming them against the product logbooks, then the required action, the compliance time, and whether it is one-time or recurring, and may use an approved Alternative Method of Compliance (AMOC). A Supplemental Type Certificate (STC) approves a design change with its own installation data.

Manufacturer maintenance manuals, illustrated parts catalogs, service bulletins (usually advisory unless mandated by an AD), and Airworthiness Limitations sections (which contain mandatory replacement times, inspection intervals, and procedures) all matter, but their regulatory force depends on context. Effectivity is itself a risk: a procedure or part may apply only to certain serial numbers or modification states, so the mechanic confirms applicability before using the data.

Inoperative equipment must be handled by rule, not convenience. Under Part 91, an item that is inoperative must be addressed through the aircraft's Minimum Equipment List (MEL) if one is authorized, or otherwise by determining the item is not required, then deactivating and placarding it "Inoperative" and making the maintenance record entry — an inoperative required item makes the aircraft unairworthy. Warnings, cautions, and notes in the data are procedural safety information identifying injury hazards, equipment-damage risks, and important steps, not filler.

Use this documentation checklist before returning an aircraft to service:

1. Identify the applicable regulation, certificate privilege, and rating.
2. Classify the work as maintenance, preventive maintenance, repair, or alteration.
3. Decide whether the repair or alteration is major or minor, and select approved vs. acceptable data accordingly.
4. Complete the correct record (43.9 maintenance entry or 43.11 inspection entry) with the required signature, certificate number, and kind of certificate, plus FAA Form 337 for a major repair or major alteration.
5. Verify AD status, TCDS/STC effectivity, MEL/placard needs, and any Airworthiness Limitation items before signing.