Aviation-related regulations that have occurred from 1926– 1966 are reflected in Figure 2-1. Just as aircraft continue to evolve with ever improving technology, so do the regulations, publications, forms, and records required to design, build, and maintain them.
The Federal Aviation Administration (FAA) regulations that govern today’s aircraft are found in Title 14 of the Code of Federal Regulations (14 CFR). [Figure 2-2] There are five volumes under Title 14, Aeronautics and Space. The first three volumes containing 75 active regulations address the Federal Aviation Administration. The fourth volume deals with the Office of the Secretary of the Department of Transportation (Aviation Proceedings) and Commercial Space Transportation, while the fifth volume addresses the National Aeronautics and Space Administration (NASA) and Air Transportation System Stabilization.
These regulations can be separated into the following three categories:
- Airworthiness Certification
- Airworthiness Operation
Since 1958, these rules have typically been referred to as “FARs,” short for Federal Aviation Regulations. However, another set of regulations, Title 48, is titled “Federal Acquisitions Regulations,” and this has led to confusion with the use of the acronym “FAR.” Therefore, the FAA began to refer to specific regulations by the term “14 CFR part XX.” Most regulations and the sections within are odd numbered, because the FAA realized in 1958 when the Civil Aeronautics Regulations were recodified into the Federal Aviation Regulations that it would be necessary to add regulations later.
Over the years, the FAA has sometimes seen the need to issue Special Federal Aviation Regulations (SFAR). [Figure 2-3] These are frequently focused very specifically on a unique situation and are usually given a limited length of time for effectiveness. Note that the SFAR number is purely a sequential number and has no relevance to the regulation it is addressing or attached to.
The remainder of this text focuses only on those regulations relative to airworthiness certification. There are 30 of these listed in Figure 2-4, and they are shown graphically in Figure 2-5. A significant benefit of this chart is the visual effect showing the interaction of the regulation with other regulations and the placement of the regulation relative to its impact on airworthiness. It is fundamentally important that the definition of the term “airworthy” be clearly understood.
Only recently did the FAA actually define the term “airworthy” in a regulation. (Refer to the 14 CFR part 3 excerpt following this paragraph.) Prior to this definition in part 3, the term could be implied from reading part 21, section 21.183. The term was defined in other non-regulatory FAA publications, and could also be implied from the text found in block 5 of FAA Form 8100-2, Standard Airworthiness Certificate. This certificate is required to be visibly placed on board each civil aircraft. (Refer to “Forms” presented later in this chapter.)
Title 14 CFR Part 3—General Requirements
Definitions. The following terms have the stated meanings when used in 14 CFR part 3, section 3.5, Statements about products, parts, appliances and materials.
- Airworthy means the aircraft conforms to its type design and is in a condition for safe operation.
- Product means an aircraft, aircraft engine, or aircraft propeller.
- Record means any writing, drawing, map, recording, tape, film, photograph or other documentary material by which information is preserved or conveyed in any format, including, but not limited to, paper, microfilm, identification plates, stamped marks, bar codes or electronic format, and can either be separate from, attached to or inscribed on any product, part, appliance or material.
Airworthiness can be divided into two areas: original airworthiness as depicted in Figure 2-5, and recurrent airworthiness as depicted in Figure 2-6. There are three primary regulations that govern the airworthiness of an aircraft:
- 14 CFR part 21—Certification Procedures for Products and Parts
- 14 CFR part 43—Maintenance, Preventive Maintenance, Rebuilding, and Alterations
- 14 CFR part 91—General Operating and Flight Rules
Note that the chart in Figures 2-5 and 2-6 show most of the other airworthiness certification regulations link to one of these regulations.
Although the history section that opens this chapter discusses the FAA as if it was a single unit, it is important to understand that there are various subgroups within the FAA, and each have different responsibilities of oversight in the aviation industry. These may vary by organizational chart or geographic location.
The maintenance technician interacts mostly with FAA personnel from the Flight Standards Service (AFS) and the Flight Standards District Office (FSDO) but may also have some interaction with FAA personnel from the Aircraft Certification Service (AIR).
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 must become familiar with. Many regulations often provide additional definitions that are unique to their use and interpretation in that specific part. Title 14 CFR part 1, section 1.2, Abbreviations and Symbols, 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 three, identifies the requirements of and the procedures for obtaining type certificates (TCs), supplemental type certificates (STCs), production certificates, airworthiness certificates, and import and export approvals. [Figure 2-5] Some of the other major areas covered in this part are the procedures for becoming a designated mechanic examiner (DME), designated aircraft maintenance inspector (DAMI), designated engineering representative, designated manufacturing inspection representative (DMIR), or designated Airworthiness Representative (DAR), or obtaining a Part Manufacture Approval (PMA) or an authorization related to producing a Technical Standard Order (TSO) part. Note that part 21’s greatest significance is in the original airworthiness phase, although it has minor application in recurrent airworthiness. [Figure 2-5] One of the most important sections of this regulation is section 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 that has been altered since it was new. This ICA is comprised of 16 specific subjects. [Figure 2-7] An ICA developed in accordance with this checklist should be acceptable to the Aviation Safety Inspector (ASI) reviewing a major alteration.
14 CFR Part 23—Airworthiness Standards: Normal, Utility, Acrobatic, and Commuter Category Airplanes
Aircraft certificated under 14 CFR 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 TC 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—Structures
- Subpart D—Design and Construction
- Subpart E—Powerplant
- Subpart F—Equipment
- Subpart G—Flightcrew Interface and Other Information
Within each of these subparts are numerous sections that specify details, such as center of gravity (CG), gust load factors, removable fasteners, the shape of certain flight deck controls, engine and propeller requirements, fuel tank markings, flight deck instrumentation marking and placards, cabin aisle width, and flammability resistant standards.
14 CFR Part 25—Airworthiness Standards: Transport Category Airplanes
The standards in 14 CFR part 25 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 14 CFR part 23. However, the ability to carry passengers is not a requirement for aircraft certified to 14 CFR part 25. Many of these aircraft are also used to transport cargo. This chapter is subdivided into similar design subpart categories and the same sequence as the requirements specified in 14 CFR part 23.
14 CFR Part 27—Airworthiness Standards: Normal Category Rotorcraft
This regulation deals with the small rotor wing aircraft and is consistent with 14 CFR part 23 with limiting the passenger seating to nine or less. However, the maximum certificated weight is limited to 7,000 pounds. It contains similar design subparts identified in 14 CFR part 23 that provide the details for designing the aircraft.
14 CFR Part 29—Airworthiness Standards: Transport Category Rotorcraft
This section specifies those standards applicable to helicopters with a maximum certified weight greater than 7,000 pounds. However, it also includes additional parameters based upon seating capacity and an additional weight limit. Those parameters are passenger seating, (nine or less, ten or more) and whether the helicopter is over or under a maximum weight of 20,000 pounds. The design subparts of part 29 are similar to those in 14 CFR parts 23, 25, and 27.
14 CFR Part 33—Airworthiness Standards: Aircraft Engines
Each of the four preceding 14 CFR regulations require that the engine used in the aircraft must be type certificated. Title 14 CFR part 33 details the requirements for both reciprocating and turbine style aircraft engines. It not only specifies the design and construction requirements, but also the block test requirements that subject the engine to extremely demanding testing in order to prove its capability of enduring the stresses of powering the aircraft.
14 CFR Part 35—Airworthiness Standards: Propellers
Just as each engine used on an aircraft must have a TC, the propeller must also be type certificated. This part is arranged the same way that 14 CFR part 33 is, in that subpart B specifies design and construction while subpart C covers tests and inspections.
Since regulations change over the years, not every aircraft presently flying meets the current design regulations as printed this year. When regulations are revised, they are printed in the Federal Register and released with an amendment number that ties them to the regulation being revised. Aircraft are required to meet only the specifications in force at the time the aircraft is built. NOTE: The preceding statement does not apply to the mandatory requirements imposed by Airworthiness Directives (AD), as these usually have a compliance date included in the text of the AD note.