FAR 21.33 — Inspections and Tests
FAR 21.33 explains the inspections and tests an applicant must perform and allow the FAA to conduct before a product can earn type certification.
In Plain English
FAR 21.33 spells out who does what during the inspection and testing phase of type certification. While most pilots will never apply for a type certificate, this rule sits behind every certificated aircraft you fly — it's how the FAA confirms a design actually meets the regs before it ever reaches the ramp.
The rule has two main parts:
- (a) FAA access. The applicant must let the FAA perform any inspection, ground test, or flight test needed to verify compliance. Before presenting an aircraft, engine, propeller, or part for FAA testing, the applicant must already have shown compliance with items (b)(2)–(b)(4), and no changes may be made to the article between that showing and the FAA test.
- (b) Applicant inspections and tests. The applicant must perform all inspections and tests needed to determine:
- Compliance with applicable airworthiness, noise, fuel venting, and exhaust emission requirements;
- That materials and products conform to the type design specifications;
- That parts conform to the type design drawings; and
- That manufacturing, construction, and assembly conform to the type design.
Operationally, this is why a production aircraft you fly matches its TCDS — the manufacturer had to prove it.
Regulation Text
14 CFR § 21.33§ 21.33 Inspection and tests.
(a) Each applicant must allow the FAA to make any inspection and any flight and ground test necessary to determine compliance with the applicable requirements of this subchapter. However, unless otherwise authorized by the FAA—
(1) No aircraft, aircraft engine, propeller, or part thereof may be presented to the FAA for test unless compliance with paragraphs (b)(2) through (b)(4) of this section has been shown for that aircraft, aircraft engine, propeller, or part thereof; and
(2) No change may be made to an aircraft, aircraft engine, propeller, or part thereof between the time that compliance with paragraphs (b)(2) through (b)(4) of this section is shown for that aircraft, aircraft engine, propeller, or part thereof and the time that it is presented to the FAA for test.
(b) Each applicant must make all inspections and tests necessary to determine—
(1) Compliance with the applicable airworthiness, aircraft noise, fuel venting, and exhaust emission requirements;
(2) That materials and products conform to the specifications in the type design;
(3) That parts of the products conform to the drawings in the type design; and
(4) That the manufacturing processes, construction and assembly conform to those specified in the type design.
[Doc. No. 5085, 29 FR 14564, Oct. 24, 1964, as amended by Amdt. 21-17, 32 FR 14926, Oct. 28, 1967; Amdt. 21-27, 34 FR 18363, Nov. 18, 1969; Amdt. 21-44, 41 FR 55463, Dec. 20, 1976; Amdt. 21-68, 55 FR 32860, Aug. 10, 1990; Amdt. 21-68, 55 FR 32860, Aug. 10, 1990; Amdt. 21-92, 74 FR 53386, Oct. 16, 2009]
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Oral Exam Questions a DPE Might Ask
Q1Who is responsible for performing the inspections and tests required during type certification?
Per FAR 21.33(b), the applicant must make all inspections and tests necessary to determine compliance, and under FAR 21.33(a) must also allow the FAA to conduct any inspection, ground test, or flight test needed to verify compliance.
Q2What four areas must the applicant verify through inspection and testing under FAR 21.33?
Under FAR 21.33(b), the applicant must verify compliance with airworthiness, noise, fuel venting, and exhaust emission requirements, and confirm that materials, parts, and manufacturing/assembly processes conform to the type design specifications and drawings.
Q3Can an applicant modify an aircraft after showing compliance but before presenting it to the FAA for testing?
No. FAR 21.33(a)(2) prohibits any changes to the aircraft, engine, propeller, or part between the time compliance with paragraphs (b)(2)–(b)(4) is shown and the time it is presented to the FAA for test, unless otherwise authorized by the FAA.
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§21.15 Type Certificate Application
FAA application form, aircraft drawings, and engine data
§21.17 Certification Basis
Applicable airworthiness, noise, and emission rules
§21.20 Compliance Showing
How applicants show compliance to the FAA
§21.31 Type Design
Drawings, specifications, dimensions, and limitations
§21.41 Type Certificate
What the certificate includes once the design is approved
§21.47 Type Certificate Transferability
Transfer and licensing notices for FAA type certificates
Related Sections in Part 21