14 CFR Part 33
70 sections · 4 appendices · 7 subparts · Amended 2026-09-15
AIRWORTHINESS STANDARDS: AIRCRAFT ENGINES
6 Legal Interpretations 46 Special Conditions 85 ELOS findings View on eCFR ↗
Authority49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
SourceDocket No. 3025, 29 FR 7453, June 10, 1964, unless otherwise noted.
Subpart A— General 6 sections
Subpart B— Design and Construction; General 11 sections
- § 33.11 Applicability.
- § 33.13 [Reserved]
- § 33.15 Materials.
- § 33.17 Fire protection.
- § 33.19 Durability.
- § 33.21 Engine cooling.
- § 33.23 Engine mounting attachments and structure.
- § 33.25 Accessory attachments.
- § 33.27 Turbine, compressor, fan, and turbosupercharger rotor overspeed.
- § 33.28 Engine control systems.
- § 33.29 Instrument connection.
Subpart C— Design and Construction; Reciprocating Aircraft Engines 6 sections
Subpart D— Block Tests; Reciprocating Aircraft Engines 10 sections
Subpart E— Design and Construction; Turbine Aircraft Engines 19 sections
- § 33.61 Applicability.
- § 33.62 Stress analysis.
- § 33.63 Vibration.
- § 33.64 Pressurized engine static parts.
- § 33.65 Surge and stall characteristics.
- § 33.66 Bleed air system.
- § 33.67 Fuel system.
- § 33.68 Induction system icing.
- § 33.69 Ignitions system.
- § 33.70 Engine life-limited parts.
- § 33.71 Lubrication system.
- § 33.72 Hydraulic actuating systems.
- § 33.73 Power or thrust response.
- § 33.74 Continued rotation.
- § 33.75 Safety analysis.
- § 33.76 Bird ingestion.
- § 33.77 Foreign object ingestion—ice.
- § 33.78 Rain and hail ingestion.
- § 33.79 Fuel burning thrust augmentor.
Subpart F— Block Tests; Turbine Aircraft Engines 17 sections
- § 33.81 Applicability.
- § 33.82 General.
- § 33.83 Vibration test.
- § 33.84 Engine overtorque test.
- § 33.85 Calibration tests.
- § 33.87 Endurance test.
- § 33.88 Engine overtemperature test.
- § 33.89 Operation test.
- § 33.90 Initial maintenance inspection test.
- § 33.91 Engine system and component tests.
- § 33.92 Rotor locking tests.
- § 33.93 Teardown inspection.
- § 33.94 Blade containment and rotor unbalance tests.
- § 33.95 Engine-propeller systems tests.
- § 33.96 Engine tests in auxiliary power unit (APU) mode.
- § 33.97 Thrust reversers.
- § 33.99 General conduct of block tests.
Subpart G— Special Requirements: Turbine Aircraft Engines 1 section
Appendices & SFARs
Related Advisory Circulars 142 current · 129 cancelled
- AC 20-135APowerplant Installation and Propulsion System Component Fire Protection Test Methods, Standards, and CriteriaCurrent2025-09-29↗
- AC 20-167BAirworthiness Approval of Enhanced Vision System, Enhanced Flight Vision System, and Combined Vision System EquipmentCurrent2025-09-08↗
- AC 33-12Geometry and Dimensional Considerations for Comparative Test and Analysis for Turbine Engine and Auxiliary Power Unit (APU) Replacement, and Repaired PartsCurrent2025-09-08↗
- AC 33.15-1AManufacturing Process of Premium Quality Titanium Alloy Rotating Engine ComponentsCurrent2025-09-08↗
- AC 20-197Turbine Engine and Airframe Sensor Icing ComplianceCurrent2025-06-18↗
- AC 33.17-1BEngine Fire Protection § 33.17Current2025-05-20↗
- 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 33.67-1Engine Fuel SystemsCurrent2024-05-20↗
- AC 20-186AAirworthiness and Operational Approval of Cockpit Voice Recorder SystemsCurrent2024-05-06↗
- 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 33.70-4Fatigue Life of Nickel Powder Rotating Life-Limited PartsCurrent2023-08-15↗
- AC 33.15-3Powder Bed Fusion Additive Manufacturing Process for Aircraft Engine PartsCurrent2023-06-23↗
- AC 33.70-3Damage Tolerance for Material Anomalies in Titanium Life-Limited Turbine Engine RotorsCurrent2023-04-17↗
- AC 33.76-1BBird Ingestion Certification StandardsCurrent2023-04-03↗
- AC 33.83-2BTurbine Engine Vibration TestCurrent2023-02-02↗
- 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 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 33.74/92-1BTurbine Engine Continued Rotation and Rotor LockingCurrent2016-06-23↗
- AC 20-153BAcceptance of Aeronautical Data Processes and Associated DatabasesCurrent2016-04-19↗
- AC 33.90-1AInitial Maintenance Inspection (IMI), 14 CFR 33.90, Test for Turbine EnginesCurrent2016-04-13↗
- 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 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 33.87-1AEngine Overtorque Test, Calibration Test, Endurance Test, and Teardown Inspection for Turbine Engine Certification (§§ 33.84, 33.85, 33.87, 33.93)Current2015-03-09↗
- 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 33-11Oxidation, Hot Corrosion, Thermal Fatigue, and Erosion Characteristics Testing to Support 14 CFR, Part 33, § 33.15, Compliancefor Turbine EnginesCurrent2014-09-23↗
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