Title 14 Code of Federal Regulations states "No person may operate a civil aircraft unless it is in airworthy
condition." (Ref; 14CFR sect. 91.7(a))
"Operation" is defined as the moment the first person boards the aircraft with the intention of flight until
the last person has disembarked. To operate a civil aircraft therefore, it must be airworthy, i.e. the aircraft must conform
to its type certificate and be in condition for safe operation.
Determining the airworthiness of an aircraft for each and every flight (operation) may seem an impossible
task. The "chart," below, will show that the method for ensuring an aircraft is airworthy dictates that the aircraft,
from its design in accordance with airworthiness standards, will be airworthy at the completion of its manufacture, when parts
are replaced, when maintenance is performed, and when it is "operated".
To better appreciate the primacy of airworthiness, a more detailed explanation of its evolution in law follows.
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Federal Aviation Regulations (14 CFR)
COMMERCIAL / CIVIL AVIATION'S FOUNDATION
THE UNITED STATES CONSTITUTION
the supreme law of the land.
Article I, Section 8, Clause 3 gives Congress the power "To regulate commerce with foreign nations,
and among the several states, and with the Indian tribes."
THE AIR COMMERCE ACT OF 1926
"An Act To encourage and regulate the use of aircraft in commerce, and for other purposes."
Section 3. Regulatory powers. "The Secretary of Commerce shall by regulation;
(b) "Provide for the rating of aircraft of the United States as to their AIRWORTHINESS.
As a basis for rating, the Secretary of Commerce (1) may require, before the granting of registration for any aircraft first
applying therefor more than eight months after the passage of this act, full particulars of the design and of the calculations
upon which the design is based and of the materials and methods used in the construction."
This was the first definition of airworthiness for civil aircraft.
The Air Commerce Act of 1926 also provided penalties for certain violations of the Act. Section 11.
Penalties, paragraph (d) states, "Any person who fraudulently forges, counterfeits, alters, or falsely makes any
certificate authorized to be issued under this act, or knowingly uses or attempts to use any such fradulent certificate shall
be guilty of an offense punishable by a fine not exceeding $1,000 or by imprisonment not exceeding three years, or by both
such fine and imprisonment."
THE CIVIL AERONAUTICS ACT OF 1938
"To create a Civil Aeronautics Authority, and to promote the development and safety and to provide for the
regulation of civil aeronautics."
Title VI "CIVIL AERONAUTICS SAFETY REGULATION, Section 603(c) AIRWORTHINESS certificate states
in part, "The registered owner of any aircraft may file with the (Civil Aeronautics) Authority an application for
an AIRWORTHINESS certificate for such aircraft. If the (Civil Aeronautics) Authority finds that the aircraft conforms to the
type certificate therfor, and, after inspection, that the aircraft is in condition for safe operation, it shall issue an AIRWORTHINESS
Notice that the more generalized "full particulars of the design and of the calculations upon which the design
is based and of the materials and methods used in the construction," cited in the Air Commerce Act of 1926 have been refined
to the present day two part definition of airworthiness; "conforms to the type certificate" and, "in condition for safe operation."
THE FEDERAL AVIATION ACT OF 1958
"To continue the Civil Aeronautics Board as an agency of the United States, to create a Federal Aviation Agency,
to provide for the regulation and promotion of civil aviation in such manner as to best foster its development and safety,
and to provide for the safe and efficient use of the airspace by both civil and military aircraft, and for other purposes."
Title VI "SAFETY REGULATION OF CIVIL AERONAUTICS, Section 603(c) AIRWORTHINESS Certificate
states in part, "The registered owner of any aircraft may file with the (Federal Aviation Agency) Administrator an application
for an AIRWORTHINESS certificate for such aircraft. If the (Federal Aviation Agency) Administrator finds that the aircraft
conforms to the type certificate therfor, and, after inspection, that the aircraft is in condition for safe operation, he
shall issue an AIRWORTHINESS certificate."
Notice that the only changes are to revise Authority to Administrator, and the pronoun it
PUBLIC LAW 103-272
"July 5, 1994, CODIFICATION OF CERTAIN U.S. TRANSPORTATION LAWS AS TITLE 49, UNITED STATES CODE. This law
expanded 49USC to include almost all permanent federal transportation law, and it simultaneously repealed the Federal
Aviation Act of 1958, among others. The new law, 49USC, states that the restatement of prior laws is done "without
substantive change," and "Those sections [that restate the law] may not be construed as making substantive change in the laws
So, that said, section 603(c) of the Federal Aviation Act of 1958 is replaced by section 44704(c)
(due to a subsequent change to the law, section 44704(c) is now section 44704(d))
of PL 103-272, to wit, in paragraph (1) "The registered owner of an aircraft may apply to the (Federal Aviation Administration)
Administrator for an AIRWORTHINESS certificate for the aircraft. The (Federal Aviation Administration) Administrator shall
issue an AIRWORTHINESS certificate when the Administrator finds that the aircraft conforms to its type certificate and, after
inspection, is in condition for safe operation."
Subtle changes, but "without substantive change" to be sure.
This is the law under which civil aviation operates today.
It is clear from the above excerpted evolution of it in Federal Law that airworthiness is comprised of two
distinctly different but mutually dependent parts; Conformance to type certificate, and, In condition
for safe operation.
Without both, an aircraft is not airworthy.
Additional supporting objective evidence of the definition and meaning of airworthiness is contained in FAA
Order 8130.2E, Airworthiness Certification of Aircraft and Related Products, issued January 23, 2003. The Foreword and Purpose
under Chapter 1, Paragraph 1 define the use, intent, and purpose of the order; "This order establishes procedures for accomplishing
original and recurrent AIRWORTHINESS certification of aircraft and related products. The procedures in this order apply to
Federal Aviation Admininstration (FAA) manufacturing aviation safety inspectors (ASI), to FAA AIRWORTHINESS ASIs, and to private
persons or organizations delegated authority to issue AIRWORTHINESS certificates and related approvals."
FAA Order 8130.2E, Chapter 1, Paragraph 9, Interpretation of the Term "Airworthy"
for U.S. Type-Certificated Aircraft states,
"The term 'AIRWORTHY' is not defined in title 49, United States Code (49
U.S.C.), or in 14 CFR; however, a clear understanding of its meaning is essential for use in the agency's AIRWORTHINESS
certification program. Below is a summary of the conditions necessary for the issuance of an AIRWORTHINESS certificate.
A review of case law relating to AIRWORTHINESS reveals two conditions that must be met for an aircraft to
be considered 'AIRWORTHY.' 49 U.S.C. section 44704(c) and 14CFR section 21.183 (a), (b), and (c)
state that the two conditions necessary for issuance of an airworthiness certificate:
a. "The aircraft must conform to its TC (type certificate). Conformity to type design (a
subset of TC - see chart below) is considered attained when the aircraft configuration and the components installed are consistent
with the drawings, specifications, and other data that are part of the TC, which includes any supplemental type certificate
(STC) and field approved alterations incorporated into the aircraft.
b. "The aircraft must be in condition for safe operation. This refers to the condition of
the aircraft relative to wear and deterioration, for example, skin corrosion, window delamination/crazing, fluid leaks, and
"NOTE: If one or both of these conditions are not met, the aircraft would be considered UNAIRWORTHY."
The two conditions necessary for airworthiness; conformance to type certificate, and in condition
for safe operation, are thereby firmly established.
The statement in paragraph 9a above, "Conformity to type design is considered attained when the aircraft configuration
and the components installed are consistent with the drawings, specifications, and other data that are part of the TC," serves
to explain the substitution of the term type design for type certificate in 14CFR section 21.183 (a), (b), and (c). Airworthy.US
has added the parenthetical (TC) at those sections in the following table for clarification.
CONFORMS TO TYPE CERTIFICATE
IN CONDITION FOR SAFE OPERATION
TYPE CERTIFICATE DEFINED:
14CFR section 21.41 states, "Each type certificate is considered to include the
TYPE DESIGN, the OPERATING LIMITATIONS, the (TYPE)
CERTIFICATE DATA SHEET, the APPLICABLE REGULATIONS of this subchapter with which
the (FAA) Administrator records compliance, and ANY OTHER CONDITIONS OR LIMITATIONS prescribed
for the product in this chapter."
TYPE DESIGN DEFINED:
14CFR section 21.31 states, "The type design consists of,
"(a) The drawings and specifications, and a listing of those drawings and specifications, necessary to define the configuration
and the design features of the product shown to comply with the requirements of that part of this subchapter applicable to
"(b) Information on dimensions, materials, and processes necessary to define the structural strength of the product;
"(c) The Airworthiness Limitations section of the Instructions for Continued Airworthiness as required by Parts 23, 25,
27, 29, 31, 33, and 35 of this chapter or as otherwise required by the (FAA) Administrator; and as specified in the applicable
airworthiness criteria for special classes of aircraft defined in (section) 21.17(b); and
"(d) For primary category aircraft, if desired, a special inspection and preventive maintenance program designed to be
accomplished by an appropriately rated and trained pilot-owner.
"(e) Any other data necessary to allow, by comparison, the determination of the airworthiness, noise characteristics,
fuel venting, and exhaust emissions (where applicable) of later products of the same type."
CERTIFICATION PROCEDURES FOR PRODUCTS AND PARTS
14 CFR PART 21
Changes to Type Certificates
Section 21.93 Classification of changes in type design (type certificate).
(a) "changes in type design are classified as minor and major. A "minor change" is one that has no appreciable effect
on the weight, balance, structural strength, reliability, operational characteristics, or other characteristics affecting
the AIRWORTHINESS of the product. All other changes are "major changes".
Section 21.95 Approval of minor change in type design (type certificate).
"Minor changes in type design (type certificate) may be approved under a method acceptable to the Administrator before
submitting to the Administrator any substantiating or descriptive data."
Section 21.97 Approval of major changes in type design (type certificate).
(a) "In the case of a major change in type design (type certificate), the applicant must submit substantiating data and
necessary descriptive data for inclusion in the type design (type certificate)."
GENERAL OPERATING AND FLIGHT RULES
14CFR PART 91
Civil Aircraft AIRWORTHINESS
(a) "No person may operate a civil aircraft unless it is in AIRWORTHY condition.
(b) "The pilot in command of a civil aircraft is responsible for determining whether that aircraft is in condition for
safe flight. The pilot in command shall discontinue the flight when unairworthy mechanical, electrical, or structural conditions
SYSTEM DESIGN AND ANALYSIS
FAA Advisory Circular AC 25.1309-1A
Equipment, systems, and installations required by Federal Aviation Regulation must be designed to function as intended
under any foreseeable operating condition, and so that any failure condition which would prevent the continued safe flight
and landing of the airplane is extremely improbable, and the occurrence of any other failure conditions which would reduce
the capability of the airplane or the ability of the crew to cope with adverse operating conditions is improbable.
SAFE FLIGHT AND LANDING:
"The capability for continued controlled flight and landing at a suitable airport, possibly using emergency procedures,
but without requiring exceptional pilot skill or strength. Some airplane damage may be associated with a failure condition,
during flight or upon landing."
OPERATING LIMITATIONS AND INFORMATION
14CFR Part 25, Subpart G
(limited in this discussion to Transport Category Airplanes like the DC-9, but similar for other type certificated
Section 25.1501 General,
"(a) Each operating limitation specified in sections 25.1501 through 25.1533 and other limitations and information necessary
for safe operation must be established.
"(b) The operating limitations and other information necessary for safe operation must be made available to the crewmembers
as prescribed in sections 25.1541 through 25.1587."
Part 25 SubPart G includes: Airspeed limitations; Maximum operating limit speed; Maneuvering
speed; Flap extended speed; Minimum control speed; Landing gear speeds; Rough air speed, V(ra); Weight, center of gravity,
and weight distribution; Powerplant limitations; Auxiliary power unit limitations; Minimum flight crew; Kinds of operation;
Ambient air temperature and operating altitude; INSTRUCTIONS FOR CONTINUED AIRWORTHINESS; Maneuvering flight load factors;
Additional operating limitations
ISSUE OF STANDARD AIRWORTHINESS CERTIFICATES...
(a) "An applicant for a standard airworthiness certificate manufactured under a production certificate is entitled to
a standard airworthiness certificate without further showing, except that the (FAA) Administrator may inspect the aircraft
to determine conformity to the type design (TC) and condition for safe operation.
(b) "An applicant for a standard airworthiness certificate for a new aircraft manufactured under a type certificate only
is entitled to a standard airworthiness certificate upon presentation, by the holder of the type certificate, of the statement
of conformity prescribed in section 21.130 ((a) "...a statement that the product conforms to its type certificate and is in
condition for safe operation") if the (FAA) Administrator finds after inspection that the aircraft conforms to the type design
(TC) and is in condition for safe operation.
(c) "An applicant for a standard airworthiness certificate for an import aircraft type certificated in accordance with
section 21.29 (Issue of type certificate: import products) is entitled to an airworthiness certificate if the country in which
the aircraft was manufactured certifies, and the (FAA) Administrator finds, that the aircraft conforms to the type design
(TC) and is in condition for safe operation."
INSTRUCTIONS FOR CONTINUED AIRWORTHINESS
14CFR Section 25.1529
"The applicant (for a type certificate) must prepare Instructions for Continued Airworthiness in accordance with appendix
H to this part that are acceptable to the (FAA) Administrator."
Appendix H to Part 25
H25.3 Content. "The manual must be prepared in English and must contain the following, and information:
(a) Airplane maintenance manual (AMM) or section. (1) Introduction section. (2) A description of the airplane,
its systems, and installations (engines, propellers, appliances, etc.). (3) Basic control and operation information. (4) Servicing
(b) Maintenance instructions. (1) Scheduling information for each part of the airplane (recommends periods at
which they should be cleaned, inspected, adjusted, tested, and lubricated), the degree of inspection, the applicable wear
tolerances, and work recommended at these periods. Also, ??the applicant must include an inspection program that includes
the frequency and extent of the inspections necessary to provide for the continued airworthiness of the airplane.? (2) Troubleshooting
information, (3) Information describing the order and method of removing and replacing products and parts, (4) Instructions
for ground run system testing, symmetry checks, weighing and C.G. determination, lifting and shoring, and storage limitations.
(c) Diagrams of structural access plates,
(d) Details for doing special inspections, e.g. radiographic and ultrasound,
(e) Information for applying protective treatments to the structure after inspection,
(f) All data relative to structural fasteners such as I.D., discard recommendations, and torque values,
(g) A list of special tools.
TYPE CERTIFICATE DATA SHEET (TCDS) explained:
That part of the TC which documents the conditions and limitations necessary to meet the airworthiness requirements of
the FARs. The TCDS provides a concise definition of the configuration of the type-certificated product. Required information
for each model aircraft TCDS includes: Engine (mfg name, engine TC number, number of installed engines); Fuel (min. fuel grade
& alt. fuels); Propeller and Propeller Limits; Rotor Speed Limits (helicopter); Transmission Torque Limits (helicopter);
Airspeed Limits; Center of Gravity (C.G.) Range; Empty Weight C.G. Range; Datum (definite, unmistakable, and unchangeable
point); Leveling Means; Maximum Weights; Minimum Crew; Number of Seats; Maximum Baggage; Fuel Capacity; Oil Capacity; Maximum
Operation Altitude; Control Surface Movement; Manufacturer's Serial Numbers; Import Requirements; Certification Basis; Production
THE APPLICABLE REGULATIONS OF THIS SUBCHAPTER WITH WHICH THE ADMINISTRATOR RECORDS COMPLIANCE.
This is also known as the certification basis, or cert basis. This defines exactly what chapters and sections of 14CFR,
and the revision dates of those chapters and sections, the aircraft complied with for its original, and properly revised,
type certificate. The certification basis is recorded in the TCDS.
ANY OTHER CONDITIONS OR LIMITATIONS PRESCRIBED BY THIS CHAPTER, explained;
Generally accepted as a sort of catch-all in the event any specific section applicable to a particular aircraft certification
is not cited
14CFR Part 21 SubPart G
Section 21.165 Responsibility of the holder;
"The holder of a production certificate shall
(a) "Maintain the quality control system in conformity with the data and procedures approved for the production certificate;
(b) "Determine that each part and each completed product submitted for airworthiness certification or approval conforms
to the approved design (because production certificates are issued for other than one of the three type certificated products
(aircraft, engine, propeller), approved design rather than type certificate is appropriate here) and is in condition
for safe operation."
REPLACEMENT AND MODIFICATION PARTS
14CFR Section 21.303
(a) "Except as provided in paragraph (b) of this section, no person may produce a modification or replacement part for
sale for installation on a type certificated product unless it is produced pursuant to a Parts Manufacturer Approval issued
under this subpart.
(b) "This section does not apply to the following:
(1) Parts produced under a type or production certificate.
(2) Parts produced by an owner or operator for maintaining or altering his own product.
(3) Parts produced under an FAA Technical Standard Order.
(4) Standard parts (such as bolts and nuts) conforming to established industry or U.S. specifications."
(k) "Each holder of a Parts Manufacturer Approval shall determine that each completed part conforms to the design data
and is safe for installation on type certificated products.".
MAINTENANCE, PREVENTIVE MAINTENANCE, REBUILDING, AND ALTERATION
14CFR PART 43
43.13 PERFORMANCE RULES (general).
(a) "Each person performing maintenance, alteration, or preventive maintenance on an aircraft, engine, propeller, or
appliance shall use the methods, techniques, and practices prescribed in the current manufacturer's maintenance manual or
Instructions for Continued Airworthiness prepared by its manufacturer, or other methods, techniques, and practices acceptable
to the (FAA) Administrator." And, "If special equipment or test apparatus is recommended by the manufacturer involved, he
must use that equipment or apparatus or its equivalent acceptable to the Administrator."
(b) "Each person maintaining or altering, or performing preventive maintenance, shall do that work in such a manner and
use materials of such a quality, that the condition of the aircraft, airframe, aircraft engine, propeller, or appliance worked
on will be at least equal to its original or properly altered condition (with regard to aerodynamic function, structural strength,
resistance to vibration and deterioration, and other qualities affecting AIRWORTHINESS)."