AC 33-2B

Advisory U.S. Department of Transportation circulor Federal Aviation Administration

FAR GUIDANCE MATERIAL Subject: AIRCRAFT ENGINE TYPE Date: 06/30/93 AC No: 33-2B CERTIFICATION HANDBOOK Initiated by: ANE-110 Change:

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,' dated June 5, 1972.

RELATED FAR SECTIONS. FAR Parts 21, 23, 25, 27, 29, 33, and

45.

4. RELATED READING MATERIAL. FAA Order 8100.5, 'Aircraft nirera 1982; and Certification Directorate Procedures," dated October 1, 1982; and FAA Order 8110.4, "Type Certification," dated December 28, 1967 through,», June (Consolidated with Changes 1 through 23, June 1985).

5. BACKGROUND.

AC 33-2A, dated June 5, 1972, was published as the "Aircraft 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 "PURPOSE" paragraph did state, The remaining chapters of the handbook pertaining to the design and testing of turbine and reciprocating engines will be issued as they become available."

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 abbreviations.

·RJACK A. SAIN Manager, Engine and Propeller Directorate Aircraft Certification Service ii

E6/0E/90 AC 33-2B Page 1 1 2 Guidance 1

GENERAL TYPE CERTIFICATION PROCEDURES 3 Purpose 3 4 Type Certificate 3 Type Certification of Aircraft Engines 3 6 Type Certificate Data 4 7 Type Certificate Data Sheet (TCDS) 5 8 Data Required 14 9 Installation Considerations of Engines 18 10 Engine Changes Which Affect Installations 19 11 Official Engine Tests 20 12 Approval of Engine Parts and Materials 21 13 Processing Changes in Type Design 21 14 Identification Plate 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 28 and Operating the Engine iii

Paragraph Page 18 Section 33.7, Engine Ratings and Operating 30 Limitations 19 Section 33.8, Selection of Engine Power and 34 Thrust Ratings SECTION 2. SUBPART B--DESIGN AND CONSTRUCTION; GENERAL 20 Section 33.14, Start-Stop Cyclic Stress (Low 37 Cycle Fatigue) 21 Section 33.15, Materials 39 22 Section 33.17, Fire Prevention 39 23 Section 33.19, Durability 42 24 Section 33.21, Engine Cooling 43 25 Section 33.23, Engine Mounting Attachments and 44 Structure 26 Section 33.25, Accessory Attachments 44 27 Section 33.27, Turbine, Compressor, Fan, and 45 Turbosupercharger Rotors 28 Section 33.29, Instrument Connection 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 53 34 Section 33.43, Vibration Test 53 iv

Paragraph Page 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 63 43 Section 33.63, Vibration 63 44 Section 33.65, Surge and Stall Characteristics 63 45 Section 33.66, Bleed Air System 64 46 Section 33.67, Fuel System 64 47 Section 33.68, Induction System Icing 66 48 Section 33.69, Ignition System 68 49 Section 33.71, Lubrication System 69 50 Section 33.72, Hydraulic Actuating Systems 71 51 Section 33.23, Power or Thrust Response 71 52 Section 33.75, Safety Analysis 72 53 Section 33.77, Foreign Object Ingestion 73 54 Section 33.79, Fuel Burning Thrust Augmenter 80 SECTION 6. SUBPART F--BLOCK TESTS; TURBINE AIRCRAFT ENGINES 55 Section 33.82, General 81

Paragraph Page 56 Section 33.83, Vibration Test 81 57 Section 33.85, Calibration Tests 83 58 Section 33.87, Endurance Test 84 59 Section 33.88, Engine Overtemperature Test 92 60 Section 33.89, Operation Test 93 61 Section 33.90, Initial Maintenance Inspection 95 62 Section 33.91, Engine Component Tests 96 63 Section 33.92, Windmilling Tests 98 64 Section 33.93, Teardown Inspection 99 65 Section 33.94, Blade Containment and Rotor 99 Unbalance Tests 66 Section 33.95, Engine-Propeller Systems Tests 100 67 Section 33.96, Engine Tests in Auxillary Power 101 Unit (APU) Mode 68 Section 33.97, Thrust Reversers 102 69 Section 33.99, General Conduct of Block Tests 103 70 Section 33.13, Design Features 104

APPENDIXES APPENDIX 1. Turbine Engine Model Description 1 APPENDIX 2. Reciprocating Engine Model Description 1 APPENDIX 3. Index of Associated Guidance Material and 1 References APPENDIX 4. Glossary of Acronyms and Abbreviations 1 vi

CHAPTER 1. INTRODUCTION 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' "Guidance," is a brief statement of the intent, and associated guidance. Following each Part 33 section, under 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.

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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. Engines Complying 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 Engines. Section 21.29 prescribes the conditions for eligibility for type certification of import engines.

c. Military Surplus Engines. 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.

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(iii) Military technical orders, comprising manual information for the engine parts list, overhaul, operation, and maintenance.

d. Helicopter Reciprocating Engines. 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.

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.

to engines require a new application for a type certificate.

a. Engine models which are of the same general series, power level, 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 instigati regulations is required, or when the proposed change is in the principle of operation.

The use of engine model number prefixes or suffixes, in lieu of new model designations, is suggested to cover many changes Chap 2 4 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:

affected significantly by changes of engine weight or performance. When interchangeability in a given model aircraft is

(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.

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 or extended range operations, result in unique maintenance requirements.

TYPE CERTIFICATE DATA SHEET (TCDS). (Reference FAR Section type Titiate part, the desertin, stings, includes the 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.

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) Heading - Numbering. 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 reterence convenience. The issue date will complete this group. The above information will be enclosed in a box to set it off.

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 certiticate 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 Designation. Show model designations in one or more columns, as necessary to exhibit ratings, limits, or Reference to recently issued TCDSs will illustrate representative ways of grouping engines in columns, and ways of accomplishing the following instructions.

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(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);

(C) Turboprop, turboshaft - same as in item (B) above, plus free (power) turbine, if appropriate.

Ratings. 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, 1bs. and

r.p.m. at sea level.

- Other, if applicable, (e.g., with water-alcohol injection, reheat, reverse thrust, or alternate ratings).

(C) For turboshaft and turboprop engines (See Note 1):

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