AC NO: 33- 2A DATE: 5 Tune 1972
ADVISORY
CIRCULAR
AIRCRAFT ENGINE TYPE CERTIFICATION HANDBOOK
DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION Initiated by: FS-140
AC NO: 33-2A DATE: 5 June 1972
ADVISORY
CIRCULAR
DEPARTMENT OF TRANSPORTATION
FEDERAL AVIATION ADMINISTRATION SUBJECT: AIRCRAFT ENGINE TYPE CERTIFICATION HANDBOOK
1. PURPOSE. This circular contains guidance relating to type certification of aircraft engines which will constitute acceptable although not the sole means of compliance with the Federal Aviation Regulations.
2. CANCELLATION. This revision completely replaces AC 33-2 issued 30 March 1966 and AC 33-2 CH 1 issued 13 September 1967, both of which are canceled.
3. REFERENCES. Federal Aviation Regulations, Parts 21, 33, and 45.
4. HOW TO GET COPIES OF THIS HANDBOOK.
a. Order copies of this publication from:
Department of Transporation Distribution Requirements Section, M-494.1 Washington, D.C. 20590
b. Identify the publication in your order as:
FAA AC 33-2A Aircraft Engine Type Certification Handbook Dated 5 June 1972
c. This publication will be furnished free of charge. CR. Melugin C. R. MELUGIN, JR.
Acting Director, Flight Standards Service Initiated by: FS-140
5 June 1972 AC 33-2A
TABLE OF CONTENTS
AIRCRAFT ENGINE TYPE CERTIFICATION HANDBOOK FAR Reference Page No.
CHAPTER 1. CERTIFICATION Purpose
2. Reserved 3 . Type Certificate 21.41 Reserved
5. Type Certification of 21.13, 21.15, 21.16, 21.17, Aircraft Engines 21.21, 21.27, 21.29, 33.
6. Reserved
7. Type Certificate Data 21.19, 21.41. 3
8. Type Certificate Data Sheet 21.41 4
9. Data Required 21.15, 21.21, 21.29, 21.31, 13
21.41, 33.5
10. Reserved 17
11. Installation Considerations 21.21 17 of Engines
12. Reserved 19
13. Engine Changes Which Affect 21.19, 21.97 19 Installations
14. Reserved 20
15. Official Engine Tests 21.33, 33. 20
16. Reserved 21
17. Approval of Engine Parts and 21.19, 21.113, 21 Materials 21.303, 33.
18. Reserved 22
19. Processing Changes in Type FAR 21, 22 Design Subparts D & E
20. Reserved 24
21. Identification Plate FAR 33 & 45, Subpart B 24
22. Reserved 24
23. Instruction Manual 33.5 24
24. Reserved 25
25. Engine Ratings & Operating 33.7 26 Limitations
26. Reserved 21
27. Selection of Engine Power & 33.8 27 Thrust Ratings CHAPTER 2. Reserved 28 APPENDIX 2. APPENDIX 1. RECIPROCATING ENGINE MODEL DESCRIPTION (5 pages) TURBINE ENGINE MODEL DESCRIPTION (6 pages) 1 Page 1
AC 33-2A 5 June 1972 CHAPTER 1. GENERAL TYPE CERTIFICATION PROCEDURES PURPOSE. This circular provides information and guidance for the type certification of aircraft engines. The acceptable means of compliance suggested are not mandatory and, therefore, need not be considered as a sole means of showing compliance with the Federal Aviation Regulations. The acceptable means of compliance serve as a guide to the public and are those which experience has shown to be both practical and effective.
a. This circular includes instructions formerly contained in Civil Aeronautics Manual Part 13.
b. Advisory circular material for insertion in the handbook will be issued periodically as it is developed. This method of issuance will facilitate the task of keeping the handbook current without the necessity for a complete revision.
C. The initial issue of the handbook contains instructions referring to FAR, Parts 21, 33, and 45. Certain portions have been reserved for future additions. The remaining chapters of the handbook pertaining to the design and testing of turbine and reciprocating engines will be issued as they become available.
2. RESERVED.
3 . TYPE CERTIFICATE. The type certificate is defined under FAR, Section 21.41.
4. RESERVED.
TYPE CERTIFICATION OF AIRCRAFT ENGINES. (Ref. FAR, Sections 21.13,
21.15, 21.16, 21.17, 21.21, 21.27, 21.29, and Part 33.)
a. Engines complying with FAR, Part 33, and Part 21. 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 any special conditions, and Section 21.17 covers designation of the applicable version of Part 33 which should be met.
b. Import Engines. Federal Aviation Regulations, Section 21.29, and SFAR 26 prescribe the conditions for eligibility for type certification of import engines. SFAR 26, issued on 8/3/70 as an interim step to modified bilateral agreements, provides for temporary continued acceptance of existing kinds of import engines, and expires 1 March 1972.
Chap 1 Par 1 Page 1
AC 33-2A 5 June 1972 Military Surplus Engines. Enginc type certification may be accomplished for military surplus engines in the same manner as is prescribed in FAR 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 FAR 21.27(c) and (e). Under FAR 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. 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 21.27(c):
(1) Military service record summary including details of mandatory safety changes required for the engine type for military service.
(2) Military qualification basis with engine model specification.
Military technical orders comprising manual information for the engine parts list, overhaul, operation, and maintenance.
Helicopter Reciprocating Engines. Helicopter engines are currently required to meet the specific test requirements of FAR, Section 33.49(d) or Section 29.923. Before this special endurance test was made effective on May 15, 1953, in Civil Air Regulations, 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 with the overspeeds often encountered in helicopters. To provide good reliability in the case of reciprocating engines which were not qualified under FAR, 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 and results in engine ratings, which are comparably qualified, as if the helicopter engine test had been the basis for engine qualification:
(1) Limit sea level engines to a maximum power rating (at full throttle) corresponding to an engine speed that is not more than 90% of the engine speed at which the original maximum full-throttle power rating was established.
Chap 1 Page 2 Par 5
5 June 1972 AC 33-2A
(2) 3) the pie the Limit altitude engines to a maximum power. rating of not more than 95% of the original maximum power rating, at an engine speed that is not more than 90% of the engine speed at which the original maximum power rating was established.
6. RESERVED.
TYPE CERTIFICATE DATA. (Reference FAR, Sections 21.19 and 21.41) General. Federal Aviation Regulations, Section 21.19, provides that some types of design changes to engines require a new application for a type certificate. Engine models which are of the same general series, displacement, and design characteristics, are usually approved under the same type certificate. 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. The use of engine serial number prefixes or suffixes in lieu of new model designations is suggested to cover many changes in engines which are important enough to warrant recognition, but which do not involve considerations necessitating that a new model designation be assigned.
Usually, only new model designations are assigned in the following instances:
(1) When interchangeability in a given model aircraft is affected significantly by weight or changes affecting performance are made in the engine.
(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 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.
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.
Chap Par 5 Page 3
AC 33-2A 5 June 1972
8. TYPE CERTIFICATE DATA SHEET. (Reference FAR, Section 21.41.)
The type certificate data sheet, formerly called the aircraft engine specification, 1s part of the type certificate, as provided in Section 21.4. of the FAR. It includes the manufacturer, model designation, limitations, and certification basis. This sheet is prepared by the FAA project engineer with assistance from the applicant. See Handbook 8110.4, para. 35, for details on preparations for printing. There is no FAA form provided for type certificate data sheets 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 as prescribed in followine (s) an 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 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, but 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 final 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 same as the type certificate number. When the data sheet the upper right-hand corner of page 1. • toved, the revisio 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, which then will be enclosed in a box to set it off.
(<) Title. The title of the document (Type Certificate Data ) will appear in the center of the page, after the heading box. Title will include exact unmodified type certificate number as shown on the type certificate.
Chap 1 Page 4 Par 8
5 June 1972 AC 33-2A Sample Preamble. Engines of models described herein conforming with this data sheet (which is a part of type certificate ) and other approved data on file with the Federal Aviation Administration, meet the minimum standards for use in certificated aircraft in accordance with pertinent aircraft data sheets and applicable portions of the Federal Aviation Regulations 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) Model Designation. Show model designations in one or more columns as necessary to exhibit correct ratings and other values or parameters for the one or more models heading given columns. Reference to the recently issued type certificate data sheets will illustrate representative ways of grouping engines in columns and ways of accomplishing the following instructions.
(b) Type. Describe engine models in terms of major generic features and processes, e.g., 1 Reciprocating, cam, etc. - number of cylinders, cylinder arrangement and cooling method, reduction gear ratio, fuel injection, supercharging, e.g., 9RA, 6HOA, IGO, IS10, etc.
Turbojet, turbofan, etc., number of compressor and turbine stages, single or multiple spool, radial or axial flow, bypass, etc., e.g., 12-stage axial flow compressor, annular combustion chamber, reverse-flow four-stage turbine.
3 Turboprop, turboshaft, etc. Same as in item 2 plus free turbine.
(c) Rating. State certificated maximum power ratings at control setting, rotational speed, pressure altitude, or other conditions as applicable for the following generic type engines.
Chap 1 Par 8 Page 5
AC 33-2A 5 June 1972 1 For reciprocating engines;
Maximum continuous, hp., r.p.m., in. Hg at:
Rated pressure altitude ft.
Takeoff (5 minutes) hp., I.p.n., in. Hg at. - S.L. Rated pressure altitude ft. Sea level pressure altitude ft. _--- Sea level pressure altitude ft. _ S.I..
Other, i1 applicable, e.g., with both low and high impeller gear ratios, antidetonant injection, and alternate fuels.
For turbojet, turbofan, and ramjet engines;
Maximum continuous static thrust, 1bs.
and r.p.m. at sea level.
Other, if applicable.
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.
3 For (1) turboshaft and (2) turboprop engines;
(1) At power turbine speed of shaft I.p.m.)
Maximum continuous at sea level; hp.
Takeoff (5 minutes) at sea level; hp.
30-minute helicopter rating at sea level; hp.
2 1/2-minute helicopter rating at sea level;hp.
Other, if applicable, e.g., with water-alcohol injection, reheat, or alternate ratings.
(2) Maximum continuous at sea level;
ESHP, SHP, jet thrust, I.p.m.
Takeoff (5 minutes) at sea level, ESHP, SHP, jet thrust, r.p.m.
Other, if applicable, e.g., with water-alcohol injection, reverse thrust, reheat, or alternate ratings.
(d) Fuel.
1 Fuel - octane, grade, or type as applicable.
2 Carburetor, fuel injector, fuel control - manufacturer, model designation, setting, or other relevant information.
3 Fuel pump (if applicable) - manufacturer, model.
Chap Page 6 Par 8
5 June 1972 AC 33-2A 4 Fuel filtration (if required for fuel at engine inlet) - mesh value.
(e) Oil.
1 Oil type or specification.
2 Oil sump (dry or wet) and capacity.
} Usable oil - engine in critical positions (degrees from reference).
(f) Coolant.
1 Coolant (liquid-cooled engine) type, specification.
2 Coolant capacity (engine only).
(g) Ignition.
Ignition (dual) magnetos or ignition supply box - models.
2 Timing (degrees BTC).
Spark plugs, igniters, and ignition exciters - models. (If extensive, put into a note.)
(h) Compressor - Compression.
1 Bore and stroke (reciprocating).
2 Displacement (reciprocating).
3 Compression ratio (reciprocating).
4 Turbosupercharger - model.
(i) Principal dimensions.
1 Length (in.) - 2 Width (in.) - 3 Height (in.) -
(j) Weight (dry) 1b. (Note any unusual inclusions or exclusions.)
Chap Par 8 Page 7
AC 33-2A 5 June 1972
(k) Center of gravity.
1 Relative to specific longitudinal reference in inches.
2 Relative to engine center line in inches.
(1) Propeller or power shaft - type and size:
(m) Crankshaft dampers - number, order, location, type.
(п) Note list - listing of note numbers applicable to model group listed under data column for that group.
(0) Legend - explanation of symbols.
1 "--" indicates "same as preceding model."
2 " " indicates "does not apply."
(P) Certification basis.
CAR-FAR effectivity covering type certification of engine.
Engine model and data of type certification.
3 Date of type certification application.
4 Date specific models canceled.
(9) Production basis. Production certificate number or other production means.
(6) Basic Data. (Notes Section) Variations are so numerous in engine type and in conditions relative to similar types that close uniformity in the use of notes for all engines appears impractical. Uniformity for uniformity's sake might well impare the accurate presentation of technical information.
The first six notes are assigned to common conditions or parameters and for uniformity should be used solely for these subjects. The remaining notes and contents may be selected according to the data to be presented. The following examples of engine data sheet notes are presented accordingly.
chap g 1 Page 8 Par
5 June 1972 AC 33-2A
(a) Common Note Headings Peculiar to All Engines.
NOTE 1. Maximum permissible temperatures or temperature limits:
Maximum Cylinder Head Cylinder Oil inlet Recip. base (Type Thermometer) Eng. Models °F.-°C. °F.-°C. °F.- °C.
OF.- °C. OF.- °C.
Turbine exhaust gas or turbine inlet temperatures measured by thermocouples at Models Models Takeoff (5 minutes) OF.- °C. °F. - C.
Maximum continuous °F.- °C. OF.- °C.
Maximum transient for °F.- °C. °F.- °C.
accel. ( ) min.
Maximum transient for °F. -°C. °F.- °C.
starting ( ) sec.
Other temperature °F.-°C.
limits as applicable.
NOTE 2. Pressure limits: Maximum Minimum Fuel inlet pressure. Altitude limits (if applicable) Oil operating pressures.
Specify eng. models as necessary.
par Page 9