14 CFR Part 21
143 sections · 1 appendices · 14 subparts · Amended 2026-09-15
CERTIFICATION PROCEDURES FOR PRODUCTS AND ARTICLES
69 Legal Interpretations 237 Special Conditions 507 ELOS findings 7574 TSOAs View on eCFR ↗
Authority42 U.S.C. 7572; 49 U.S.C. 106(f), 40105, 40113, 44701-44702, 44704, 44707, 44709, 44711, 44713, 44715, 45303.
SourceDocket No. 5085, 29 FR 14564, Oct. 24, 1964, unless otherwise noted.
Subpart A— General 9 sections
- § 21.1 Applicability and definitions.
- § 21.2 [Reserved]
- § 21.3 Reporting of failures, malfunctions, and defects.
- § 21.4 ETOPS reporting requirements.
- § 21.5 Airplane or Rotorcraft Flight Manual.
- § 21.6 Manufacture of new aircraft, aircraft engines, and propellers.
- § 21.7 Continued airworthiness and safety improvements for transport category airplanes.
- § 21.8 Approval of articles.
- § 21.9 Replacement and modification articles.
Subpart B— Type Certificates 27 sections
- § 21.11 Applicability.
- § 21.13 Eligibility.
- § 21.15 Application for type certificate.
- § 21.16 Special conditions.
- § 21.17 Designation of applicable regulations.
- § 21.19 Changes requiring a new type certificate.
- § 21.20 Compliance with applicable requirements.
- § 21.21 Issue of type certificate: normal, utility, acrobatic, commuter, and transport category aircraft; manned free balloons; special classes of aircraft; aircraft engines; propellers.
- § 21.23 [Reserved]
- § 21.24 Issuance of type certificate: primary category aircraft.
- § 21.25 Issue of type certificate: restricted category aircraft.
- § 21.27 Issue of type certificate: surplus aircraft of the Armed Forces.
- § 21.29 Issue of type certificate: import products.
- § 21.31 Type design.
- § 21.33 Inspection and tests.
- § 21.35 Flight tests.
- § 21.37 Flight test pilot.
- § 21.39 Flight test instrument calibration and correction report.
- § 21.41 Type certificate.
- § 21.43 Location of manufacturing facilities.
- § 21.45 Privileges.
- § 21.47 Transferability.
- § 21.49 Availability.
- § 21.50 Instructions for continued airworthiness and manufacturer's maintenance manuals having airworthiness limitations sections.
- § 21.51 Duration.
- § 21.53 Statement of conformity.
- § 21.55 Responsibilities of type certificate holders who license the type certificate.
Subpart C— Provisional Type Certificates 8 sections
- § 21.71 Applicability.
- § 21.73 Eligibility.
- § 21.75 Application.
- § 21.77 Duration.
- § 21.79 Transferability.
- § 21.81 Requirements for issue and amendment of Class I provisional type certificates.
- § 21.83 Requirements for issue and amendment of Class II provisional type certificates.
- § 21.85 Provisional amendments to type certificates.
Subpart D— Changes to Type Certificates 6 sections
Subpart E— Supplemental Type Certificates 6 sections
Subpart F— Production Under Type Certificate 8 sections
Subpart G— Production Certificates 16 sections
- § 21.131 Applicability.
- § 21.132 Eligibility.
- § 21.133 Application.
- § 21.135 Organization.
- § 21.137 Quality system.
- § 21.138 Quality manual.
- § 21.139 Location of or change to manufacturing facilities.
- § 21.140 Inspections and tests.
- § 21.141 Issuance.
- § 21.142 Production limitation record.
- § 21.143 Duration.
- § 21.144 Transferability.
- § 21.145 Privileges.
- § 21.146 Responsibility of holder.
- § 21.147 Amendment of production certificates.
- § 21.150 Changes in quality system.
Subpart H— Airworthiness Certificates 18 sections
- § 21.171 Applicability.
- § 21.173 Eligibility.
- § 21.175 Airworthiness certificates: classification.
- § 21.177 Amendment or modification.
- § 21.179 Transferability.
- § 21.181 Duration.
- § 21.182 Aircraft identification.
- § 21.183 Issue of standard airworthiness certificates for normal, utility, acrobatic, commuter, and transport category aircraft; manned free balloons; and special classes of aircraft.
- § 21.184 Issue of special airworthiness certificates for primary category aircraft.
- § 21.185 Issue of airworthiness certificates for restricted category aircraft.
- § 21.187 Issue of multiple airworthiness certifications for restricted category aircraft.
- § 21.189 Issue of airworthiness certificate for limited category aircraft.
- § 21.190 Issue of a special airworthiness certificate for a light-sport category aircraft.
- § 21.191 Issue of experimental airworthiness certificates.
- § 21.193 Application for special airworthiness certificates issued for experimental purposes.
- § 21.195 Experimental airworthiness certificates: Aircraft to be used for market surveys, sales demonstrations, and customer crew training.
- § 21.197 Special flight permits.
- § 21.199 Issue of special flight permits.
Subpart I— Provisional Airworthiness Certificates 8 sections
- § 21.211 Applicability.
- § 21.213 Eligibility.
- § 21.215 Application.
- § 21.217 Duration.
- § 21.219 Transferability.
- § 21.221 Class I provisional airworthiness certificates.
- § 21.223 Class II provisional airworthiness certificates.
- § 21.225 Provisional airworthiness certificates corresponding with provisional amendments to type certificates.
Subpart K— Parts Manufacturer Approvals 13 sections
- § 21.301 Applicability.
- § 21.303 Application.
- § 21.305 Organization.
- § 21.307 Quality system.
- § 21.308 Quality manual.
- § 21.309 Location of or change to manufacturing facilities.
- § 21.310 Inspections and tests.
- § 21.311 Issuance.
- § 21.313 Duration.
- § 21.314 Transferability.
- § 21.316 Responsibility of holder.
- § 21.319 Design changes.
- § 21.320 Changes in quality system.
Subpart L— Export Airworthiness Approvals 6 sections
Subpart N— Acceptance of Aircraft Engines, Propellers, and Articles for Import 2 sections
Subpart O— Technical Standard Order Approvals 15 sections
- § 21.601 Applicability and definitions.
- § 21.603 Application.
- § 21.605 Organization.
- § 21.607 Quality system.
- § 21.608 Quality manual.
- § 21.609 Location of or change to manufacturing facilities.
- § 21.610 Inspections and tests.
- § 21.611 Issuance.
- § 21.613 Duration.
- § 21.614 Transferability.
- § 21.616 Responsibility of holder.
- § 21.618 Approval for deviation.
- § 21.619 Design changes.
- § 21.620 Changes in quality system.
- § 21.621 Issue of letters of TSO design approval: Import articles.
Subpart P— Special Federal Aviation Regulations 1 section
Related Advisory Circulars 142 current · 153 cancelled
- AC 21-12DApplication for U.S. Airworthiness CertificateCurrent2026-01-30↗
- AC 20-135APowerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards, and CriteriaCurrent2025-09-29↗
- AC 21-32CControl of Prepositioned Products and Articles Shipped Prior to Design ApprovalCurrent2025-09-25↗
- AC 20-167BAirworthiness Approval of Enhanced Vision System, Enhanced Flight Vision System, and Combined Vision System EquipmentCurrent2025-09-08↗
- AC 21.17-4Type Certification----Powered-liftCurrent2025-07-18↗
- AC 20-197Turbine Engine and Airframe Sensor Icing ComplianceCurrent2025-06-18↗
- AC 20-146AMethodology for Dynamic Seat Certification by Analysis for Use in Parts 23, 25, 27, and 29 Airplanes and RotorcraftCurrent2024-11-29↗
- AC 20-154AGuide for Developing a Receiving Inspection System for Aircraft Parts and MaterialsCurrent2024-07-03↗
- AC 20-158BThe Certification of Aircraft Electrical and Electronic Systems for Operation in the High-Intensity Radiated Fields (HIRF) EnvironmentCurrent2024-05-20↗
- AC 20-186AAirworthiness and Operational Approval of Cockpit Voice Recorder SystemsCurrent2024-05-06↗
- AC 21-58Safety Management Systems for Part 21 Type and Production Certificate HoldersCurrent2024-04-26↗
- AC 20-29CApproval and Use of Fuel System Icing Inhibitors (FSII)Current2024-03-27↗
- AC 20-193Use of Multi-Core ProcessorsCurrent2024-01-08↗
- AC 20-105CReciprocating Engine Power-Loss Accident Prevention and Trend MonitoringCurrent2023-12-18↗
- AC 20-109BService Difficulty Reporting System (Air Operator/Air Agency/General Aviation/Unmanned Aircraft Systems)Current2023-11-01↗
- AC 20-152ADevelopment Assurance for Airborne Electronic HardwareCurrent2022-10-07↗
- AC 20-189Management of Open Problem Reports (OPRs)Current2022-09-16↗
- AC 20-185AAirworthiness Approval of Synthetic Vision Systems, Synthetic Vision Guidance Systems and Aircraft State Awareness Synthetic Vision SystemsCurrent2021-01-27↗
- AC 20-144AFAA Approval of Electrical Firing Cartridge Components in an Aircraft Fire Extinguishing or Suppression SystemCurrent2018-10-11↗
- AC 20-162BAirworthiness Approval of Installed Radio Frequency Identification (RFID) Tags and SensorsCurrent2018-10-11↗
- AC 20-53CProtection of Aircraft Fuel Systems Against Vapor Ignition Caused by LightningCurrent2018-09-24↗
- AC 20-62EEligibility, Quality, & Identification of Aeronautical Replacement PartsCurrent2018-09-14↗
- AC 20-190Aircraft Electromagnetic Compatibility CertificationCurrent2018-06-25↗
- AC 20-115DAirborne Software Development Assurance Using EUROCAE ED-12( ) and RTCA DO-178( )Current2017-07-21↗
- AC 20-151CAirworthiness Approval of Traffic Alert and Collision Avoidance Systems (TCAS II), Versions 7.0 & 7.1 and Associated Mode S TranspondersCurrent2017-07-21↗
- AC 20-164ADesigning and Demonstrating Aircraft Tolerance to Portable Electronic DevicesCurrent2017-06-09↗
- AC 21-46ATechnical Standard Order ProgramCurrent2017-02-23↗
- AC 20-188Compatibility of Changes to Type Design Installed on AircraftCurrent2016-12-09↗
- AC 20-182AAirworthiness Approval for Aircraft Weather Radar SystemsCurrent2016-10-01↗
- AC 20-140CGuidelines for Design Approval of Aircraft Data Link Communication Systems Supporting Air Traffic Services (ATS)Current2016-09-28↗
- AC 20-160AOnboard Recording of Controller Pilot Data Link Communication (CPDLC) In Crash Survivable MemoryCurrent2016-09-28↗
- AC 21-55Process to Support FAA Findings of Undue Burden or No Undue Burden for PAHs Requesting to Use a Manufacturing Facility Located Outside of the United StatesCurrent2016-08-01↗
- AC 21-29DDetecting and Reporting Suspected Unapproved PartsCurrent2016-07-12↗
- AC 20-153BAcceptance of Aeronautical Data Processes and Associated DatabasesCurrent2016-04-19↗
- AC 21.101-1BEstablishing the Certification Basis of Changed Aeronautical ProductsCurrent2016-03-11↗
- AC 21-25BApproval of Modified Seating System Initially Approved Under a Technical Standard OrderCurrent2016-01-11↗
- AC 20-77BUse of Manufacturers’ Maintenance ManualsCurrent2016-01-04↗
- AC 20-149BInstallation Guidance for Domestic Flight Information Service- BroadcastCurrent2015-12-21↗
- AC 20-165BAirworthiness Approval of Automatic Dependent Surveillance - Broadcast OUT SystemsCurrent2015-12-07↗
- AC 20-184Guidance on Testing and Installation of Rechargeable Lithium Battery and Battery Systems on AircraftCurrent2015-10-15↗
- AC 21-43AProduction Under 14 CFR Part 21,Subparts F, G, K, and OCurrent2015-10-01↗
- AC 21-44AIssuance of Export Airworthiness Approvals Under 14 CFR Part 21 Subpart LCurrent2015-10-01↗
- AC 20-18BQualification Testing of Turbojet and Turbofan Engine Thrust ReversersCurrent2015-07-07↗
- AC 20-172BAirworthiness Approval for ADS-B In Systems and ApplicationsCurrent2015-05-20↗
- AC 21-54Experimental Airworthiness Certification of Certain Former Military AircraftCurrent2015-02-15↗
- AC 20-150BAirworthiness Approval of Satellite Voice (SATVOICE) Equipment Supporting Air Traffic Service (ATS) CommunicationCurrent2014-12-23↗
- AC 20-183Laser Airworthiness Installation GuidanceCurrent2014-12-15↗
- AC 20-166AIssue Paper ProcessCurrent2014-11-06↗
- AC 20-147ATurbojet, Turboprop, Turboshaft, and Turbofan Engine Induction System Icing and Ice IngestionCurrent2014-10-22↗
- AC 20-24DApproval of Propulsion Fuels, Additives, and Lubricating OilsCurrent2014-06-30↗
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