Chapter 12. Publications, Forms, & Records

Maintenance Related Regulations

14 CFR Part 1 — Definitions and Abbreviations

This section is a very comprehensive, but certainly not all inclusive, list of definitions that both pilots and mechanics should become familiar with. Many regulations often provide additional definitions, which are unique to their use and interpretation in that specific part.

The Abbreviations and Symbols section (§1.2) tends to be highly focused on those abbreviations related to flight.

14 CFR Part 21 — Certification Procedures for Products and Parts

This regulation (the first of the “Big Three" identified earlier) identifies the requirements of and the procedures for obtaining type certificates, supplemental type certificates, production certificates, airworthiness certificates, and import and export approvals. Some of the other major areas covered in this part are the authorization procedures for obtaining a delegation option authorization, becoming a designated alteration station (DAS), or obtaining a Part Manufacture Approval (PMA) or an authorization related to producing a Technical Standard Order (TSO) part are also included in this regulation. Note that most of the part 21 triangle lies to the left of the vertical line reflecting its significance in the original airworthiness phase. [Figure 12-5] One of the most important sections of this regulation is §21.50, Instructions for continued airworthiness and manufacturer’s maintenance manuals having airworthiness limitations sections. When an aircraft is delivered new from the manufacturer, it comes with maintenance manuals that define the inspection and maintenance actions necessary to maintain the aircraft in airworthy condition. Also any STC modification that was developed after 1981 must have, as part of the STC documentation, a complete set of instructions for continued airworthiness (ICA). This ICA contains inspection and maintenance information intended to be used by the technician in maintaining that part of the aircraft which has been altered since it was new. This ICA is comprised of 16 specific subjects. [Figure 12-6.] An ICA developed in accordance with this checklist should be acceptable to the ASI reviewing major alteration.


14 CFR Part 23 — Airworthiness Standards: Normal, Utility, Acrobatic, and Commuter Category Airplanes

Aircraft certificated under part 23 represent the greatest portion of what the industry refers to as “general aviation." These aircraft vary from the small two-place piston engine, propeller-driven trainers that are frequently used for flight training, to turbine powered corporate jets used to transport business executives. Seating capacity is limited to nine or less on all aircraft except the commuter aircraft where the maximum passenger seating is 19, excluding the pilot and copilot seats.

This part specifies the airworthiness standards that must be met in order for a manufacturer to receive a type certificate and for the aircraft to receive an airworthiness certificate. Part 23 aircraft are those aircraft that have a maximum certificated takeoff weight of 12,500 pounds or less, except for those aircraft in the commuter category. The maximum certificated takeoff weight limit rises to 19,000 pounds or less for these aircraft.

Part 23 has seven subparts, six of them providing detailed criteria for the design of these aircraft. The first, Subpart A, defines the applicability of this regulation. The others are:

  • Subpart B — Flight
  • Subpart C — Structure
  • Subpart D — Design and Construction
  • Subpart E — Powerplant
  • Subpart F — Equipment
  • Subpart G — Operating Limitations and Information

Within each of these subparts are numerous sections that specify details, such as center of gravity, gust load factors, removable fasteners, the shape of certain cockpit controls, engine and propeller requirements, fuel tank markings, cockpit instrumentation marking and placards, cabin aisle width, and flammability resistant standards.

14 CFR Part 25 — Airworthiness Standards: Transport Category Airplanes

The standards in this part apply to large aircraft with a maximum certificated takeoff weight of more than 12,500 pounds. This segment of aviation is usually referred to as “commercial aviation" and includes most of the aircraft seen at a large passenger airport, except for the commuter aircraft included in part 23. However, the ability to carry passengers is not a requirement for aircraft certified to part 25. Many of these aircraft are also used to transport cargo. This chapter is subdivided into the same design subpart categories and the same sequence as the requirements specified in part 23.

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