the same engine model must be able to achieve the rated power or thrust for compliance with these requirements. For example, an engine model may have several power or thrust management configurations realized by what are known as “rating plugs.” These configurations are acceptable only if the engine is able to obtain the rated power or thrust without exceeding the operating limitations. In other words, the rating plugs should not restrict obtaining the rated power or thrust, otherwise the engine is not compliant with § 33.8(b).
c. The applicant should provide the means by which to determine that any engine, regardless if new or in-service, can produce the type certificate rated power or thrust within the rating’s operating limitations. For example, engine acceptance tests or performance check tests may satisfy this requirement when included or referenced in the type certification documentation.
The power or thrust verified through these tests should be corrected to the conditions used to determine the rating and listed in the TCDS (refer to § 33.8 (b) and paragraph 6.f. of this AC).
The corrected power or thrust should not be less than the rated value listed in the TCDS;
otherwise, the engine is not compliant with its type design.
d. The applicant must also include in the TCDS the variation of the rated power or thrust with the ambient temperature. For example, for a flat rated engine, the rated power or thrust remains constant up to the ambient temperature when one or more operating limitations are reached.
Beyond this temperature, known as “corner point,” the available power or thrust decreases.
Francis A. Favara, Manager, Engine and Propeller Directorate Aircraft Certification Service.
Appendix 1
APPENDIX 1: Examples of TCDS Annotations for Engine Ratings and Operating Limitations per § 33.7(c)(1)
The type certificate data sheet (TCDS) is part of a type certificate (TC), and includes ratings and operating limitations. The following are examples of how to annotate the TCDS for turbojet and turboshaft engine ratings and operating limitations.
1. Example of TCDS annotations for the rated thrust of a turbojet engine with extended takeoff thrust (up to 10 minutes for OEI events):
RATINGS - Sea level static thrust (lbs) - Note 1
ENGINE MODELS MODEL 1 MODEL 2 MODEL 3 Rated takeoff (5 minute)
- Note 2
60,000 55,000 65,000 Rated maximum continuous 54,000 48,000 59,000
Note 1: Engine ratings are based on calibrated engine test stand for the following conditions:
• Static sea level standard conditions based on the International Civil Aviation Organization (ICAO) Standard Atmosphere conditions.
• No customer bleed-air extraction and no customer power extraction.
• No anti-icing airflow; no inlet distortion; no inlet screen losses; and 100% ram recovery.
• Production engine inlet [P/N] and exhaust [P/N].
Note 2: The rated takeoff thrust may be used for up to 10 minutes in the event one engine on a multi-engine airplane becomes inoperative during takeoff.
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Appendix 1
2. Example of TCDS annotations for turbojet engine maximum permissible speeds:
Maximum permissible speeds (R.P.M.)
ENGINE MODELS MODEL 1 MODEL 2 MODEL 3 High Pressure Rotor (N2) Rated takeoff 15,450 15,400 15,600 Rated maximum continuous 15,200 15,400 15,300 Low Pressure Rotor (N1) Rated takeoff 7,700 7,400 7,800 Rated maximum continuous 7,400 7,300 7,500
3. Example of TCDS annotations for turbojet engine maximum permissible gas temperatures:
ENGINE MODELS Maximum permissible gas temperature - interturbine temperature (T4.5
- ITT) (ºF) MODEL 1 MODEL 2 MODEL 3 Rated takeoff 1,690 1,630 1,740 Rated maximum continuous 1,600 1,560 1,650 Starting 1,470 1,470 1,470
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Appendix 1
4. Example of TCDS annotations for the rated power of a turboshaft engine with continuous OEI and 30-second/2-minute OEI ratings:
RATINGS - Sea level shaft horsepower (SHP) - Note 1
ENGINE MODELS MODEL 1 MODEL 2 MODEL 3 Rated takeoff (5 minute) 1,650 2,000 2,500 Rated maximum continuous 1,500 1,750 2,000 Rated continuous OEI 1,600 1,950 2,450 Rated 2-minute OEI, Note 2 1,650 1,970 2,470 Rated 30-second OEI, Note 3 2,000 2,700 2,850
Note 1: Engine ratings are based on calibrated engine test stand for the following conditions:
• Static sea level standard conditions based on ICAO Standard Atmosphere conditions.
• No customer bleed-air extraction and no customer power extraction.
• No anti-icing airflow; no inlet distortion; no inlet screen losses; and 100% ram recovery.
• Production engine inlet [P/N] and exhaust [P/N].
Note 2: Limited in use for up to three periods no longer than 2 minutes each in any one flight, and followed by mandatory inspection and prescribed maintenance action.
Note 3: Limited in use for up to three periods no longer than 30 seconds each in any one flight, and followed by mandatory inspection and prescribed maintenance action.
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Appendix 1
5. Example of TCDS annotations for turboshaft engine maximum permissible speeds:
Maximum permissible gas generator speeds (R.P.M.)
ENGINE MODELS MODEL 1 MODEL 2 MODEL 3 Rated takeoff 44,600 45,000 45,100 Rated maximum continuous 44,000 43,500 44,000 Rated continuous OEI 44,500 43,700 44,200 Rated 2-minute OEI 44,600 44,700 45,000 Rated 30-second OEI 45,700 46,000 46,000 Transient (10 seconds) 47,000 47,000 47,000
6. Example of TCDS annotations for turboshaft engine maximum permissible gas temperatures:
Maximum permissible gas temperature (ºF) – exhaust gas temperature (EGT)
ENGINE MODELS MODEL 1 MODEL 2 MODEL 3 Rated takeoff 1,700 1,750 1,800 Rated maximum continuous 1,500 1,550 1,600 Rated continuous OEI 1,660 1,710 1,760 Rated 2-minute OEI 1,720 1,770 1,820 Rated 30-second OEI 1,750 1,800 1,850 Transient (10 seconds) 1,770 1,820 1,870
7. Example of TCDS annotation for turboshaft engine maximum power turbine shaft torque:
Maximum power turbine shaft torque (ft-lb) Note 1:
ENGINE MODELS MODEL 1 MODEL 2 MODEL 3 Rated takeoff 500 550 620 Rated maximum continuous 450 520 560 Rated continuous OEI 500 530 580 Rated 2-minute OEI 520 600 640 Rated 30-second OEI 580 650 670 Transient (10 seconds) 700 700 700 Note 1: Shaft torque is measured at the shaft output location.
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Appendix 2
APPENDIX 2: Revision History of Definitions for Turbine Engine Ratings
1. The FAA first adopted engine ratings in the Civil Aviation Regulation (CAR) as CAR-13, amendment 1 in 1957. That amendment introduced and defined takeoff power or thrust rating and the maximum continuous power or thrust rating. The information in this appendix is arranged in chronological order, as ratings definitions were revised, starting with CAR 13-1 through part 33, amendment 25.
2. Rated takeoff and maximum continuous thrust, augmented and unaugmented:
a. The definitions first adopted for these ratings were under the nomenclatures of “takeoff thrust” and “maximum continuous thrust” in CAR-13 by amendment 1, effective 8/12/1957.
b. Rating nomenclatures were later changed in § 1.1 by amendment 3 to part 33, effective 4/3/1967, from “takeoff thrust” to “rated takeoff thrust” and from “maximum continuous thrust” to “rated maximum continuous thrust.” In addition, the definitions were revised with regard to the test conditions required for developing the rated thrust.
c. The current definitions for these ratings were introduced in § 1.1 by amendment 6 to part 33, effective 10/31/1974. This amendment revised existing definitions as follows:
(1) Revised the “rated takeoff thrust” and “rated maximum continuous thrust” definitions to clarify they are “unaugmented,” by adding “without fluid injection and without the burning of fuel in a separate combustion chamber.”
(2) Added new definitions for the “rated takeoff thrust augmented” and “rated maximum continuous thrust augmented.”
3. Rated takeoff and maximum continuous power, augmented and unaugmented:
a. The definitions first adopted for these ratings were under the nomenclatures of “takeoff power” and “maximum continuous power” in CAR-13 by amendment 1, effective 8/12/1957.
b. Rating nomenclatures were later changed in § 1.1 by amendment 3 to part 33, effective 4/3/1967, from “takeoff power” to “rated takeoff power” and from “maximum continuous power” to “rated maximum continuous power.” In addition, the definitions were revised with regard to the test conditions required for developing the rated power. These are the current definitions.
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Appendix 2
c. No definitions exist in part 1.1 for “rated takeoff power augmented” and “rated maximum continuous power augmented.” However, these ratings are identified in part 33 regulations, including 33.7 and 33.87. Although these definitions were not added during prior amendments,
they are similar to the definitions for the “rated takeoff thrust augmented” and “rated maximum continuous thrust augmented.”
4. Rated 30-minute OEI power, § 33.7(c)(1)(v).
a. This rating was adopted in CAR 13 by amendment 5, effective 2/12/1963, and its definition was added in § 13.1.
b. The rating’s nomenclature was later changed in § 1.1 and part 33 by original version, effective 2/1/1965, from “30-minute power for helicopter turbine engines” to “30-minute power.”
c. The next revision to this rating’s definition was introduced in § 1.1 by amendment 3 to part 33, effective 4/3/1967. The “30-minute power” nomenclature was amended by inserting the word “rated” before 30-minute power to read: “rated 30-minute power.”
d. The next revision to this rating’s definition was introduced in § 1.1 by amendment 12 to part 33, effective 10/3/1988. This revision added “OEI” to the rating nomenclature to read “rated 30-minute OEI power” to better identify its intended use.
e. The rating’s definition was later revised in § 1.1 by amendment 25 to part 33, effective 10/17/2008. The OEI condition was revised from “the failure of one engine” to “the failure or shutdown of one engine.” The definition remains unchanged to date.
5. Rated 2½-minute OEI power, § 33.7(c)(1)(vi).
a. This rating was adopted in CAR 13 by amendment 6, effective 4/22/1964, and its definition was added in § 13.1.
b. The rating’s nomenclature was later changed in § 1.1 and part 33 by original version, effective 2/1/1965, from “2 ½-minute power for helicopter turbine engines” to “2½-minute power” with the same definition.
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Appendix 2
c. The next revision to this rating’s definition was introduced in § 1.1 by amendment 3 to part 33, effective 4/3/1967. The “2½-minute power” was amended by inserting the word “rated” before the 2½-minute power to read: “rated 2½-minute power.”
d. The next revision to this rating’s definition was introduced in § 1.1 by amendment 12 to part 33, effective 10/3/1988. This revision added “OEI” to the rating nomenclature to read “rated 2½-minute OEI power” to better identify its intended use.
e. The rating’s definition was later revised in § 1.1 by amendment 25 to part 33, effective 10/17/2008. The OEI condition was revised from “the failure of one engine” to “the failure or shutdown of one engine.” This revision also clarified that more than a single 2½-minute period is permitted for one flight by changing from “limited in use to a period of not more than 2½ minutes” to “for periods of use no longer than 2½ minutes each.” The definition remains unchanged to date.
6. Rated continuous OEI power, § 33.7(c)(1)(vii).
a. This rating was adopted in § 1.1 and part 33 by amendment 12, effective 10/3/1988.
b. The rating’s definition was later revised in § 1.1 by amendment 25 to part 33, effective 10/17/2008. The OEI condition was revised from “the failure of one engine” to “the failure or shutdown of one engine.” The definition remains unchanged to date.
7. Rated 2-minute OEI power, § 33.7(c)(1)(viii).
a. This rating was adopted in § 1.1 and part 33 by amendment 18, effective 8/19/1996.
b. The rating’s definition was later revised in § 1.1 by amendment 25 to part 33, effective 10/17/2008. The OEI condition was revised from “the failure of one engine” to “the failure or shutdown of one engine.” The definition remains unchanged to date.
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Appendix 2
8. Rated 30-second OEI power, § 33.7(c)(1)(ix).
a. This rating was adopted in § 1.1 and part 33 by amendment 18, effective 8/19/1996.
b. The rating’s definition was later revised in § 1.1 by amendment 25 to part 33, effective 10/17/2008. The OEI condition was revised from “the failure of one engine” to “the failure or shutdown of one engine.” The definition remains unchanged to date.
9. Auxiliary power unit (APU) mode of operation in § 33.7(c)(1)(x) was adopted in part 33 by amendment 11, effective 4/24/1986. There is no definition for this rating in § 1.1.
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