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CS-E 740 Endurance Tests

Available versions for ERULES-1963177438-11529

ED Decision 2018/014/R found in: CS-E Amdt 5 - Engines (Dec 2018)

Version Text

CS-E 740 Endurance Tests

ED Decision 208/014/R

(a) The specifications of this CS-E 740 must be varied and supplemented as necessary to comply with [CS-E 690(a)](#_DxCrossRefBm1371447771), [CS-E 750](#_DxCrossRefBm1371447789) and [CS-E 890](#_DxCrossRefBm1371447569).

(b) (1) The test must be made in the order defined in the appropriate schedule and in suitable non-stop stages. An alternative schedule may be used if it is agreed to at least as severe. In the event of a stop occurring during any stage, the stage must be repeated unless it is considered to be unnecessary. The complete test may need to be repeated if an excessive number of stops occur.

(2) The time taken in changing power and / or thrust settings during the entire test must not be deducted from the prescribed periods at the higher settings.

(3) Throughout each stage of the endurance test, the rotational speed must be maintained at, or within agreed limits of, the declared value appropriate to a particular condition. The determination of the necessary rotational speed tolerance will take account of the Engine speed, test equipment and any other relevant factors (see also CS-E 740(f)(1)).

(4) On turbo-propeller Engines, a representative flight Propeller must be fitted.

(5) The Engine must be subjected to an agreed extent of pre-assembly inspection, and a record must be made of the dimensions that are liable to change by reason of wear, distortion and creep. A record must also be made of the calibrations and settings of separately functioning Engine components and equipment (e.g. the control system, pumps, actuators, valves).

(1) Schedule for Standard Ratings (Take-off and Maximum Continuous)

25 6-hour stages, each stage comprising:

Part 1 1 hour of alternate 5-minute periods at Take-off Power or Thrust and minimum ground idle, or, for rotorcraft Engines, minimum test bed idle.

Part 2

(A) Stages 1 to 15, each of 30 minutes duration, at Maximum Continuous Power or Thrust.

(B) Stages 16 to 25, each of 30 minutes duration, at Take-off Power or Thrust.

For Engines for Aeroplanes. Where Engine rotational speeds between Maximum Continuous and Take-off may be used in service, e.g. for reduced thrust take-off or due to variations in the ambient temperature, and these speeds would not be adequately covered by other Parts of the endurance test, then the following Part 2 must be substituted:

(D) Stages 11 to 15, each of 30 minutes duration at Take-off Power or Thrust.

(E) Stages 16 to 25, each of 30 minutes duration covering the range in 6 approximately equal speed increments between Maximum Continuous and Takeoff Power or Thrust.

Part 3 1 hour and 30 minutes at Maximum Continuous Power or Thrust.

Part 4 2 hours and 30 minutes covering the range in 15 approximately equal speed increments from Ground Idling up to but not including Maximum Continuous Power or Thrust.

Part 5 30 minutes of accelerations and decelerations consisting of 6 cycles from Ground Idling to Take-off Power or Thrust, maintaining Take-off Power or Thrust for a period of 30 seconds, the remaining time being at Ground Idling.

(2) (i) Schedule for Standard Ratings with 2½-Minute OEI and/or Continuous OEI Rating and/or 30-Minute OEI Rating and/or 30-Minute Power (when appropriate).

25 6-hour stages, each stage comprising:

Part 1 1 hour of alternate 5-minute periods at Take-off Power or Thrust and minimum ground idle, or, for rotorcraft Engines, minimum test bed idle, except that –

(A) In Stages 3 to 20, in place of two of the 5-minute periods at Take-off Power or Thrust, run 2½ minutes at Take-off Power or Thrust followed by 2½ minutes at 2½-Minute OEI Power or Thrust.

(B) In Stages 21 to 25, in place of three of the 5-minute periods at Take-off Power or Thrust, run 1 minute at Take-off Power or Thrust followed by 2 minutes at 2½Minute OEI Power or Thrust and 2 minutes at Take-off Power or Thrust.

Part 2

(A) Stages 1 to 15, each of 30 minutes duration at Maximum Continuous Power or Thrust.

(B) Stages 16 to 25, each of 30 minutes duration at Take-off Power or Thrust, except that in one stage a period of 5 minutes in the middle of a 30-minute period must be run at 2½-Minute OEI Power or Thrust.

(D) Stages 16 to 20, each of 30 minutes duration at Take-off Power or Thrust except that in Stage 16 a period of 5 minutes in the middle of the 30-minute period must be run at 2½-Minute OEI Power/Thrust.

(E) Stages 21 to 25, each of 30 minutes duration covering the range in six approximately equal speed increments between Maximum Continuous and Take-off Power or Thrust.

Part 3

(A) For Engines for Aeroplanes:

30 minutes at Maximum Continuous Power or Thrust followed by one hour at Continuous OEI Power or Thrust.

(B) For Engines for Rotorcraft –

Either (for Engines to be approved with a Continuous OEI rating) 30 minutes at Maximum Continuous Power followed by 1 hour at Continuous OEI Power or (for Engines to be approved with a 30-Minute OEI Rating) 1 hour at Maximum Continuous Power followed by 30 minutes at 30-Minute OEI Power. A Continuous OEI Rating and a 30-Minute OEI Rating at a higher power level can be cleared in the same test, if desired, by running 30 minutes at Maximum Continuous Power followed by 30 minutes at Continuous OEI Power and then 30 minutes at 30-Minute OEI Power.

For an Engine to be approved with the 30-Minute Power rating, the Engine must be run for continuous periods of 30 minutes at the power level and associated operating limitations of the 30-Minute Power rating. These periods must be alternated with periods at Maximum Continuous Power, or less. The accumulated total additional running time shall be 25 hours at the 30-Minute Power rating, and the time spent at ‘standard’ Take-off Power shall not be counted towards this total.

Part 4 2 hours and 30 minutes covering the range in 15 approximately equal increments from Ground Idling, or, for rotorcraft Engines, minimum test bed idle, up to but not including Maximum Continuous Power.

Part 5 30 minutes of accelerations and decelerations consisting of 6 cycles from Ground Idling, or, for rotorcraft Engines, minimum test bed idle, to Take-off Power or Thrust, maintaining Take-off Power or Thrust for a period of 30 seconds, the remaining time being at Ground Idling, or, for rotorcraft Engines, minimum test bed idle.

(ii) If only one additional rating is required, then the periods at the rating that is not required must be run at the power or thrust level appropriate to the next rating down the scale.

(iii) If a constructor desires an en-route OEI rating for 30 minutes only, then the appropriate FAR 33.87 Schedule may be used in place of this Schedule. If this option is taken and a 2½ - Minute OEI Power rating is also desired, then the appropriate Schedule of FAR 33.87 must be used.

(3) For Engines with 30-Second and 2-Minute OEI Power ratings (See [AMC E 740(c)(3)](#_DxCrossRefBm1371447787)),

(i) If a Continuous OEI Power rating is associated with the 30-Second and 2-Minute OEI Power ratings, the following tests must be conducted and must be complemented by the additional test of CS-E 740(c)(3)(iii):

25 six-hour stages, each stage comprising –

Part 1 One hour of alternate 5 minute periods at Take-off Power and minimum test bed idle.

Part 2

(A) Stages 1 to 15, each of 30 minutes duration at Maximum Continuous Power.

(B) Stages 16 to 25, each of 30 minutes duration at Take-off Power.

Part 3 One hour at Maximum Continuous Power, followed by one hour at Continuous OEI Power.

Part 4 2 hours covering the range in 12 approximately equal increments from minimum test bed idle up to, but not including, Maximum Continuous Power.

Part 5 30 minutes of accelerations and decelerations consisting of 6 cycles from minimum test bed idle to Take-off Power, maintaining Take-off Power for a period of 30 seconds, the remaining time being at minimum test bed idle.

(ii) If a 30-Minute OEI Power rating is associated with the 30-Second and 2-Minute OEI Power ratings, the following tests must be conducted and must be complemented by the additional test of CS-E 740(c)(3)(iii):

25 six-hours stages, each stage comprising:

Part 1: One hour of alternate 5-minute periods at Take-off Power and minimum test bed idle.

Part 2:

(A) Stages 1 to 15, each of 30 minutes duration at Maximum Continuous Power.

(B) Stages 16 to 25, each of 30 minutes duration at Take-off Power.

Part 3: One hour at Maximum Continuous Power, followed by thirty minutes at 30-Minute OEI Power.

Part 4: Two hours and thirty minutes covering the range in 15 approximately equal increments from minimum test bed idle to Maximum Continuous Power.

Part 5: 30 minutes of accelerations and decelerations consisting of 6 cycles from minimum test bed idle to Take-off power, maintaining Take-off Power for a period of 30 seconds, the remaining time being at minimum test bed idle.

(iii) The following test sequence must be performed four times for a total time of not less than 120 minutes. If a stop occurs during this test, the interrupted sequence must be repeated unless it is shown that the severity of the test is not reduced if it were continued:

Part 1: Three minutes at Take-off Power.

Part 2: Thirty seconds at 30-Second OEI Power.

Part 3: Two minutes at 2-Minute OEI Power.

Part 4: Five minutes at whichever is the greatest of, as applicable, 30-Minute OEI Power, Continuous OEI Power and Maximum Continuous Power, except that during the first test sequence this period must be sixty-five minutes. However, where the greatest is the 30-Minute OEI Power, that sixty-five minutes period must consist of thirty minutes at 30-Minute OEI Power followed by thirty-five minutes at whichever is the greater of Continuous OEI Power and Maximum Continuous Power, as applicable.

Part 5: One minute at 50 percent of Take-off Power.

Part 6: Thirty seconds at 30-Second OEI Power.

Part 7: Two minutes at 2-Minute OEI Power.

Part 8: One minute at flight idle.

(d) *Accelerations and Decelerations*

(1) During scheduled accelerations and decelerations in Parts 1 and 5,

(i) For aeroplane Engines, the power or thrust control lever must be moved from one extreme position to the other in a time not greater than one second.

(ii) For rotorcraft Engines, the power demand must be increased to Take-off from the minimum test bed idle in a time not greater than one second.

(2) Observations

(i) Turbine Engines for Aeroplanes.

(A) Readings of power/ thrust, speed and Exhaust Gas Temperature must be recorded at every significant change of Engine conditions. Following accelerations, the over-run of speed and temperature above the steady conditions at Take-off must be noted.

(B) Observations of all parameters must be recorded on first establishing steady running conditions and thence, during periods of continuous steady running, at approximately 30-minute intervals.

(C) During cyclic or other running, sufficient observations must be made to establish the power/thrust, speed and temperature conditions of the Engine whenever significant readings can be taken.

(ii) Turbine Engines for Rotorcraft.

Readings of power, rotational speed, nozzle position and Exhaust Gas Temperature must be taken at idling speed and at the maximum speed obtained on acceleration. The over run of speed and temperature above the steady conditions at Take-off Power must be noted. These observations are likely to be affected by the types of instruments used and must therefore be coupled with this information in the endurance test report.

(e) *Oil Pressure.* The whole of the endurance test must be run with the oil pressure set to a value which is within the limits declared for Engine acceptance, except that –

(1) Stage 22 must be run with the pressure set to give that declared as the minimum for completion of the flight, at Maximum Continuous conditions, and

(2) One other stage must be run with the pressure set to give that declared as the maximum normal, at maximum continuous conditions. During this stage the oil temperature need not be held at its maximum value. Alternatively, this test may be omitted from the endurance test if appropriate evidence is available from other testing.

(f) *Operating Limitations.* The normal Engine operating limitations of power, rotational speed, turbine entry temperature, oil temperature, etc., to be established under [CS-E 40(d)](#_DxCrossRefBm1371447587) and [CS-E 40(g)](#_DxCrossRefBm1371447587), will be based on the mean values obtained during the appropriate periods of the endurance test, including, when applicable, the mean values obtained during the applications of the 30-Second and 2-Minute OEI Power conditions in the 2-hour additional endurance test sequence of CS-E 740 (c)(3)(iii).

Similarly, the degrees of compressor and turbine bleed that may be approved are the percentages of the mass flow which have been demonstrated during the endurance test, except as provided by [CS-E 690(a)(3)(ii)](#_DxCrossRefBm1371447771).

(1) The characteristics of multi-spool Engines may be such that it is not possible to obtain the maximum rotational speed of each spool simultaneously at sea-level test bed conditions, without making the Engine unacceptably non-standard, or running it in a non-representative manner. In such circumstances, the endurance test must be run at the turbine entry temperatures for which approval is sought, and evidence from supplementary endurance testing, to a schedule acceptable to the Agency, must be provided to substantiate the approval of any higher rotational speed limitations desired. (See [AMC E 740(f)(1)](#_DxCrossRefBm1371447788))

(2) If Stages 3, 7, 13, 17 and 23, with bleed(s) in operation, require the use of a rotational speed less than the maximum without bleed (as permitted by [CS-E 690(a)(1)(iii)](#_DxCrossRefBm1371447771)), these Stages need not be included in the assessment of the mean rotational speed value, subject to agreement by the Agency.

(3) In the case of Engines incorporating free power-turbines, if the requisite periods are not run at the maximum power-turbine torque for which approval is sought, evidence of additional running will be required. This may be obtained from tests equivalent to the endurance test on a similar Engine, the endurance test Engine or the relevant parts of it. In all such additional running the appropriate periods must be run at the maximum rotational speed for which approval of the maximum torque is required.

(4) Temperatures.

(i) All periods of the test corresponding to a rating to be approved must be run at the appropriate maximum declared turbine entry temperature for this rating unless otherwise agreed. The means of achieving this (e.g. by adjustment of the nozzle areas, the use of bleed) must be justified.

(ii) In general, essentially the average of the maximum temperatures achieved during the appropriate periods of the test will be utilised to establish the operating limitations of temperature for the Engine. The average Exhaust Gas Temperatures will be reduced, however, by the amounts necessary to ensure that the turbine entry temperatures in flight do not exceed the turbine entry temperatures established by endurance test at the appropriate rating conditions. During the accelerations and short periods at Take-off Power, attempts must be made to run at maximum temperatures but if, owing to the unstabilised conditions, lower temperature readings are recorded, these need not be included in calculating the average.

(iii) Engines for Aeroplanes. Where the Engine characteristics are such that an acceleration from cold produces a transient over-temperature in excess of that for steady state running, a maximum turbine gas temperature limit for acceleration with a time limitation of 2 minutes may be approved by running at the required temperature for the first 2 minutes of each prescribed period at Take-off Power conditions for 5 minutes or more, and for the whole of all the 30-second periods at Take-off Power. Approval for short period transient conditions at 2½-Minute OEI Power will not be considered and any temperature clearance required must be demonstrated normally during the 2½-Minute OEI periods of the endurance test.

(iv) Engines for Rotorcraft. Where the Engine characteristics are such that an acceleration from cold produces a transient over-temperature in excess of that for steady state running, a maximum Exhaust Gas Temperature limit for acceleration with a time limitation of 2 minutes may be approved by running at the required temperature for the first 2 minutes of each prescribed period at Take-off Power conditions in excess of 2 minutes (and for the whole of all the 30-second Take-off Power periods for single-engined rotorcraft). Approval for short period transient conditions at 2½-Minute OEI Power will not be considered, and any temperature clearance required must be demonstrated normally during the endurance test.

(v) For all Take-off Power/Thrust periods of 5 minutes or greater, 5 minutes must be run at the maximum oil inlet temperature declared for the condition, with the remainder of each 30minute period at Take-off Power/Thrust being run at the normal oil temperature for take-off. If a 10-minute Take-off Power/Thrust Rating is sought, then 10 minutes of each 30-minute period at Take-off Power/Thrust must be run at the maximum oil temperature. For all Maximum Continuous Power/Thrust periods 30 minutes must be run at the maximum oil inlet temperature declared for the condition, the remainder of each 1½ hour period at Maximum Continuous Power/Thrust being run at the normal oil temperature for climb/cruise.

(vi) Where necessary to cater for short-duration rise of indicated oil temperature under service conditions above the maximum established during the endurance test such higher temperature may be approved as the Maximum Oil Temperature (with an appropriate time limitation) without additional endurance testing, provided that it can be demonstrated that –

(A) The temperature rise under service conditions is the result of a local increase in the oil temperature at the temperature sensing position (e.g. as may occur on reducing power at the top of the climb when fuel is used as the oil cooling medium),

(B) There is no significant increase in the maximum local temperature of either the Engine components or the oil in any Engine Critical Part, and

(C) There is no undue deterioration of the oil in such circumstances and no adverse effect on any system using the oil as a working fluid (e.g. Propeller control).

(g) *Incremental Periods.*

(1) If a significant vibration response is found to exist on relevant components in the course of establishing compliance with [CS-E 650](#_DxCrossRefBm1371447570) at any condition within the operating range of the Engine (not prohibited under [CS-E 650(f)](#_DxCrossRefBm1371447570)), not less than 10 hours, but not exceeding 50%, of the incremental periods of Part 4 of the endurance test must be run with the rotational speed varied continuously over the range for which vibrations of the largest amplitude were disclosed by the vibration survey; if there are other ranges of rotational speed within the operational range of the Engine where approximately the same amplitude exists, a further 10 hours must be run in the same way for each such range. The speed variation must be effected by automatic means using a method acceptable to the Agency. (See [AMC E 740(g)(1)](#_DxCrossRefBm1371447787))

(2) In the case of Engines operating at constant speed, the thrust and/or power may be varied in lieu of speed, in Part 4 of the endurance test.

(3) In the case of free power-turbine Engines, the normal operating range of power-turbine speed must be covered. This may be run concurrently with the range of gas generator speed.

(4) In the case of a free power-turbine Engine for Rotorcraft, 10 minutes of Part 4 in each stage of the endurance test must be run at the Maximum Power-turbine Speed for Autorotation with the gas generator producing the most critical conditions associated with this flight configuration.

(h) Inspection Checks

(1) After completion of the test, the Engine must be subject to a strip inspection, and the dimensions measured in accordance with CS-E 740(b)(5) must be re-measured and recorded. The condition of the Engine must be satisfactory for safe continued operation. Separately functioning Engine components and equipment must be functionally checked prior to strip to ensure that any changes in function or settings are satisfactory for normal operation.

(2) Engines with 30-Second and 2-Minute OEI Power ratings must be subjected to a full strip inspection after completing the additional endurance test of CS-E 740(c)(3)(iii). (See [AMC E 740(h)(2)](#_DxCrossRefBm1371447786))

(i) If the Engine was not subject to a strip examination before commencing the additional endurance test then the strip inspection specifications of CS-E 740(h)(1) apply on completion of the test.

(ii) If it is proposed to subject the Engine to a strip examination before commencing the additional endurance test, the Engine must be reassembled using the same parts used during the 150 hours test run, except those parts described as consumable in the Engine documentation.

(iii) After this additional endurance test, the Engine may exhibit deterioration in excess of that permitted in CS-E 740(h)(1), and it is accepted that some Engine parts may be unsuitable for further use. It must be shown by inspection, analysis and/or test or by any combination thereof that the structural integrity of the Engine is maintained.

[Amdt No: E/1]

[Amdt No: E/4]

[Amdt No: E/5]