U.S. Department of Transportation Federal Aviation u Administration Circular
FAR GUIDANCE MATERIAL Subject: AIRCRAFT ENGINE TYPE Date: 06/30/93 AC No: 33-28 CERTIFICATION HANDBOOK Initiated by: ANE-110 change:
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1. PURPOSE. This advisory circular (AC) provides methods acceptable to the Administrator for showing compliance with the type certification requirements of aircraft engines in Part 33, inclusive through amendment 12, of the Federal Aviation Regulations (FAR). The procedures and guidance material provided in this AC may be used by an applicant seeking issuance of a type certificate, an amended type certificate, or a supplemental type certificate for the initial approval of a new type design, or a change in the type design. Consideration will be given to any other method of compliance the applicant elects to present. This information is not in itself mandatory, but serves as a guide to engine manufacturers, engine modifiers, and Federal Aviation Administration (FAA) engine type certification engineers.
Individuals should be guided by the intent of the methods provided in this AC.
2. CANCELLATION. This revision supersedes AC 33-2A, "Aircraft Engine Type Certification Handbook,tt dated June 5, 1972.
3. RELATED FAR SECTIONS. FAR Parts 21, 23, 25, 27, 29, 33, and
45.
4. RELATED READING MATERIAL. FAA Order 8100.5, "Aircraft Certification Directorate Procedures,'t dated October 1, 1982; and FAA Order 8110.4, "Type Certification," dated December 28, 1967 (Consolidated with Changes 1 through 23, June 1985).
5. BACKGROUND.
AC 33-2A, dated June 5 1972, was published as the llAir%aft Engine Type CertificAtion Handbook." The material therein principally addressed guidance on the procedural aspects of Part 21, but offered very little guidance for Part 33.
However, the last sentence of the l@PURPOSEIV paragraph did state, 'IThe remaining chapters of the handbook pertaining to the design and testing of turbine and reciprocating engines will be issued as they become available.n
b. This revision updates and presents the existing procedural information within Chapter 2, and incorporates, within Chapter 3, -
engine type certification rules and guidance material which has since been developed. The appendixes provide turbine and reciprocating engine model descriptions, an index of guidance material and references, and a glossary of acronyms and -c 1-p JA’C;;’ f. SAIN Manager, Engine and Propeller Directorate Aircraft Certification Service - ii
CONTENTS Paraqraph CHAPTER 1. INTRODUCTION 1 General 2 Guidance CHAPTER 2. GENERAL TYPE CERTIFICATION PROCEDURES 3 Purpose 4 Type Certificate 5 Type Certification of Aircraft Engines 6 Type Certificate Data 7 Type Certificate Data Sheet (TCDS) 8 Data Required 9 Installation Considerations of Engines 10 Engine Changes Which Affect Installations 11 Official Engine Tests 12 Approval of Engine Parts and Materials 13 Processing Changes in Type Design 14 Identification Plate Paqe 1 1 3 3 3 4 5 14 18 19 20 21 21 23 CHAPTER 3. TYPE CERTIFICATION GUIDANCE MATERIAL SECTION 1. SUBPART A--GENERAL 15 Section 33.3, General 25 16 Section 33.4, Instructions for Continued 25 Airworthiness (Amendment 33-9) 17 Section 33.5, Instruction Manual for Installing 2% and Operating the Engine iii
Paraqraph Paqe 18 19 SECTION 2. SUBPART B--DESIGN AND CONSTRUCTION; GENERAL 20 Section 33.14, Start-Stop Cyclic Stress (Low Cycle Fatigue) 21 22 23 24 25 26 Section 33.25, Accessory Attachments 27 Section 33.27, Turbine, Compressor, Fan, and Turbosupercharger Rotors 28 Section 33.29, Instrument Connection Section 33.7, Engine Ratings and Operating Limitations Section 33.8, Selection of Engine Power and Thrust Ratings Section 33.15, Materials Section 33.17, Fire Prevention Section 33.19, Durability Section 33.21, Engine Cooling Section 33.23, Engine Mounting Attachments and Structure 30 34 37 39 39 42 43 44 44 45 49 SECTION 3. SUBPART C--DESIGN AND CONSTRUCTION; RECIPROCATING
AIRCRAFT ENGINES 29 Section 33.33, Vibration 51 30 Section 33.35, Fuel and Induction System 51 31 Section 33.37, Ignition System 52 32 Section 33.39, Lubrication System 52 SECTION 4. SUBPART D--BLOCK TESTS; RECIPROCATING AIRCRAFT
ENGINES 33 Section 33.42, General 34 Section 33.43, Vibration Test 53 53 iv
- Paraqraph Paqe 35 Section 33.45, Calibration Tests 54 36 Section 33.47, Detonation Tests 55 37 Section 33.49, Endurance Test 55 38 Section 33.51, Operation Test 60 39 Section 33.53, Engine Component Tests 60 40 Section 33.55, Tear Down Inspection 61 41 Section 33.57, General Conduct of Block Tests 61 SECTION 5. SUBPART E--DESIGN AND CONSTRUCTION; TURBINE
AIRCRAFT ENGINES 42 Section 33.62, Stress Analysis 43 Section 33.63, Vibration 44 45 46 47 48 49 50 51 52 53 54 Section 33.65, Surge and Stall Characteristics Section 33.66, Bleed Air System Section 33.67, Fuel System Section 33.68, Induction System Icing Section 33.69, Ignition System Section 33.71, Lubrication System Section 33.72, Hydraulic Actuating Systems Section 33.23, Power or Thrust Response Section 33.75, Safety Analysis Section 33.77, Foreign Object Ingestion Section 33.79, Fuel Burning Thrust Augmenter 63 63 63 64 64 66 68 69 71 71 72 73 80 SECTION 6. SUBPART F--BLOCK TESTS; TURBINE AIRCRAFT ENGINES 55 Section 33.82, General 81
Paraqraph Paqe 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 Section 33.83, Vibration Test Section 33.85, Calibration Tests Section 33.87, Endurance Test Section 33.88, Engine Overtemperature Test Section 33.89, Operation Test Section 33.90, Initial Maintenance Inspection Section 33.91, Engine Component Tests Section 33.92, Windmilling Tests Section 33.93, Teardown Inspection Section 33.94, Blade Containment and Rotor Unbalance Tests Section 33.95, Engine-Propeller Systems Tests Section 33.96, Engine Tests in Auxiliary Power Unit (APU) Mode Section 33.97, Thrust Reversers Section 33.99, General Conduct of Block Tests Section 33.13, Design Features
APPENDIXES APPENDIX 1. Turbine Engine Model Description APPENDIX 2. Reciprocating Engine Model Description APPENDIX 3. Index of Associated Guidance Material and References APPENDIX 4. Glossary of Acronyms and Abbreviations 81 83 84 92 93 95 96 98 99 99 100 101 102 103 104 vi
w CHAPTER 1. INTRODUCTION
1. GENERAL. This advisory circular (AC) provides procedural and guidance material for the type certification (TC) of aircraft engines. The AC covers certain sections of Parts 21 and 33 of Subchapter C, Chapter 1, Title 14, of the Code of Federal Regulations (CFR). This AC is considered to be a living document.
As such, it will be amended on an as-needed basis to maintain currency, such as with the issuance of Part 33 rules changes, or the development of substantive new guidance material.
2. GUIDANCE. The TC guidance presented is referred to the specific regulatory requirement to which it applies. As a convenience to the user, the FAR Part 33 regulatory requirements, presented in Chapter 3, are reprinted herein to provide a cohesive single-source book for engine type certification; i.e., procedures, rules, and associated guidance. Following each Part 33 section, under "Guidance," is a brief statement of the intent, followed by a listing of documents incorporated as pertinent guidance material; and a second listing of related bibliographic material, followed by specific discussions, where applicable.
- Chap 1 Par 1 1 (and 2)
CHAPTER 2. GENERAL TYPE CERTIFICATION PROCEDURES
3. PURPOSE. This chapter provides information and guidance material on the certification procedures of FAR Part 21 which may be employed for engine type certification projects.
4. TYPE CERTIFICATE. The type certificate is defined under FAR Section 21.41.
5. TYPE CERTIFICATION OF AIRCRAFT ENGINES. (Reference FAR Sections 21.13, 21.15, 21.16, 21.17, 21.21, 21.27, 21.29, and FAR Part 33).
a. Enqines Complyinq with Parts 21 and 33. Engines tested and approved to the airworthiness standards of FAR Part 33 are eligible to receive a type certificate. Section 21.13 covers applicant eligibility; Section 21.15 covers application for type certificate; Section 21.16 covers the establishment of special conditions; and Section 21.17 covers designation of the applicable version of Part 33 which should be met.
b. Import Enqines. Section 21.29 prescribes the conditions for eligibility for type certification of import engines.
C. Military Surplus Enqines. Engine type certification may be accomplished for military surplus engines in the same manner as is prescribed in Section 21.21 for other engines, but these engines may also be made eligible for use without being type certificated, in accordance with the provisions of Sections
21.27(c) and (e).
(1) Under Sections 21.27(c) and (e), military surplus engines may be approved for use on military surplus aircraft, if it is shown on the basis of previous military qualifications acceptance and service record, that the engine provides substantially the same level of airworthiness as would be provided if the engine were type certificated under Part 33, with appropriate special conditions and later requirements applied.
(2) The engine characteristics necessary for installation, operation, and identification of the engine should be listed on the pertinent military surplus aircraft type certification data sheet. The following engine technical data are helpful in identifying engine limits and showing compliance with FAR Section 21.27(c):
(i) Military service record summary, including details of mandatory safety changes required for the engine type for military service.
(ii) Military qualification basis, with engine model specifications.
Chap 2 Par 3 3
(iii) Military technical orders, comprising manual information for the engine parts list, overhaul, operation, and maintenance.
d. Helicopter Reciprocatinq Enqines. Helicopter reciprocating engines are currently required to meet the specific test requirements of Section 33.49(d), Sections 29.923 and 27.927, or Sections 29.923 and 29.927, as appropriate.
(1) Before this special endurance test was made effective on May 15, 1953, in the Civil Air Regulations (CAR) Part 13, it became evident from service experience that some engines operated in helicopters were hazardous and unreliable, because of the characteristically high steady engine speeds and powers at which overspeeds were often encountered in helicopters.
(2) To provide good reliability in the case of reciprocating engines which were not qualified under Section
33.49(d), or have not been shown to have equivalent capabilities, it is suggested that they be derated. The following method of derating is suggested, as it results in engine ratings which are comparably qualified, as if the helicopter engine test had been the basis for engine qualification:
(i) Limit sea level engines to a maximum power rating (at full throttle), corresponding to an engine speed that is not more than 90 percent of the engine speed at which the original maximum full-throttle power rating was established.
(ii) Limit altitude engines to a maximum power rating of not more than 95 percent of the original maximum power rating, at an engine speed that is not more than 90 percent of the engine speed at which the original maximum power rating was established.
6. TYPE CERTIFICATE DATA. (Reference FAR Sections 21.19 and
21.41). Section 21.19 provides that some types of design changes to engines require a new application for a type certificate.
leve?;
Engine models which are of the same general series, power and design characteristics, are usually approved under the same type certificate.
b. A new type certificate is required when the proposed changes in design or limitations are so extensive that a substantially complete investigation of compliance with applicable regulations is required, or when the proposed change is in the principle of operation.
C. The use of engine model number prefixes or suffixes, in lieu of new model designations, is suggested to cover many changes 4 Chap 2 Par 5
-- .- - in engines which are important enough to warrant recognition, but which do not involve considerations necessitating that a new model designation be assigned.
d. New model designations are usually assigned in the following instances:
(1) When interchangeability in a given model aircraft is affected significantly by changes of engine weight or performance.
(2) When propeller mounting, propeller vibration damping, or control provisions are changed so as to preclude use of certain types of propellers on all engines of the same model.
(3) When, as a result of design changes, the horsepower or thrust ratings are changed a significant amount (on the order of 20 percent or more), in excess of the accepted tolerance of output measurement.
(4) When special ratings are granted an existing engine model because of incorporation of new design features.
(5) When a significant change is made in the mounting characteristics of an engine, design of cowling or baffles integral with the engine, exhaust port locations, oil supply sump, accessories, or control characteristics.
(6) When a design change results in significant changes in vibration characteristics, heat rejection through oil or coolant, or other operational characteristics.
(7) When special applications, for example, agricultural use, or extended range operations, result in unique maintenance requirements.
7. TYPE CERTIFICATE DATA SHEET (TCDS). (Reference FAR Section
21.41) The TCDS is part of the type certificate. It includes the type certificate holder, model designation, ratings, limitations, and certification basis. This sheet is prepared by the FAA project engineer, with assistance from the applicant. See FAA Order 8110.4, Paragraph 35, for details on preparations for printing. There is no FAA form provided for TCDSs because of the variations in the required data associated with the various products. The following guidelines provide general information relative to uniform handling of the engine data sheet, with reference to the desired descriptive data content and general arrangement to be considered in the preparation of this sheet.
a. General. Applicable details, as prescribed in following paragraphs, constitute the official status of the engine(s) and serve as a guide for identification, use, and installation of engines in aircraft. The formal arrangement of data, explanatory Chap 2 Par 6 5
notes, and extent of detail provided should conform, in general, to that shown for the most recently certificated comparable types of engines. Extensive details of engineering installation data are not desirable and this data may be merely referenced.
However, specific data should be indicated, if feasible. The assistance of the applicant is desirable in formulating and assuring the accuracy of the data sheets. Standardization of data sheet format is desirable whenever possible, and specifically for the same generic type engines consistent with the following recommendations. The project engineer should have the draft data sheet completed by the time the type certificate is issued.
b. Detailed Description.
(1) Headinq - Numberinq. The data sheet number will appear in the upper right-hand corner of page 1. This number will be the same as the type certificate number. When the data sheet is revised, the revision number will be shown as a suffix. The name of the type certificate holder, in abbreviated form, will be included next, together with all the approved models listed in alphabetical, or numerical, order for reference convenience. The issue date will complete this group. The above information will be enclosed in a box to set it off.
(2) Title. The title of the document (Type Certificate Data Sheet No. ) will appear in the center of the page, after the heading box. The title will include the exact, unmodified, type certificate number, as shown on the type certificate.
(3) Sample Preamble. Engines of models described here that conform with this data sheet (which is a part of Type Certificate No. ) and other approved data on file with the FAA, meet the minimum standards for use in certificated aircraft, in accordance with pertinent aircraft data sheets and applicable portions of the FAR, provided they are installed, operated, and maintained; as prescribed by the FAA approved manufacturer's manuals and other FAA approved instructions.
(4) Type Certificate Holder. Insert the exact name and address of the type certificate holder as shown on the type certificate.
(5) Basic Data. (Main Section).
(i) Model Desiqnation. Show model designations in one or more columns, as necessary to exhibit ratings, limits, or other parameters for each of the models. Reference to recently issued TCDSs will illustrate representative ways of grouping engines in columns, and ways of accomplishing the following instructions.
Chap 2 Par 7
(ii) Type. Describe engine models in terms of major generic features and processes. For example:
(A) Reciprocating - number of cylinders, cylinder arrangement and cooling method, reduction gear ratio, fuel injection, and supercharging (e.g., 9RA, 6HOA, IGO, TSIO);
(B) Turbojet, turbofan - number of compressor and turbine stages, single or multiple spool, radial or axial flow, bypass, etc., (e.g., 12-stage axial flow compressor, reverse-flow annular combustor, four-stage turbine);
(Cl Turboprop, turboshaft - same as in item (B) above, plus free (power) turbine, if appropriate.
(iii) Ratinqs. State certificated maximum power ratings at control setting, rotational speed, pressure altitude, ambient temperature, or other conditions as applicable for the following generic type engines:
(A) For reciprocating engines:
- Maximum continuous horsepower, r.p.m., in. Hg at:
-- Rated pressure altitude ft. ---- -- Sea level pressure altitude ft. S.L. ---
- Takeoff (5 minutes) horsepower, r.p.m., in. Hg at:
-- Rated pressure altitude ft. ---- -- Sea level pressure altitude ft. S.L. ---
- Other, if applicable, (e.g., with both low and high impeller gear ratios, anti-detonator injection, or alternate fuels).
(B) For turbojet and turbofan engines:
- Maximum continuous static thrust, lbs. and -- r.p.m. at sea level.
- Takeoff (5 minutes) static thrust, lbs. and --
r.p.m. at sea level.
- Other, if applicable, (e.g., with water-alcohol injection, reheat, reverse thrust, or alternate ratings).
Note 1):
(C) For turboshaft and turboprop engines (See Chap 2 Par 7