ED Decision 2003/15/RM
(a) Each powerplant cooling system must be able to maintain the temperatures of powerplant components within the limits established for these components under critical surface (ground or water) and flight operating conditions for which certification is required and after normal shutdown. Powerplant components to be considered include but may not be limited to engines, rotor drive system components, auxiliary power units, and the cooling or lubricating fluids used with these components.
(b) Compliance with sub-paragraph (a) must be shown in tests conducted under the conditions prescribed in that paragraph.
ED Decision 2003/15/RM
(a) General. For the tests prescribed in CS 27.1041(b), the following apply:
(1) If the tests are conducted under conditions deviating from the maximum ambient atmospheric temperature specified in sub-paragraph (b), the recorded powerplant temperatures must be corrected under sub-paragraphs (c) and (d) unless a more rational correction method is applicable.
(2) No corrected temperature determined under sub-paragraph (a)(1) may exceed established limits.
(3) For reciprocating engines, the fuel used during the cooling tests must be of the minimum grade approved for the engines, and the mixture settings must be those normally used in the flight stages for which the cooling tests are conducted.
(4) The test procedures must be as prescribed in CS 27.1045.
(b) Maximum ambient atmospheric temperature. A maximum ambient atmospheric temperature corresponding to sea-level conditions of at least 38°C (100°F) must be established. The assumed temperature lapse rate is 1.98°C (3.6°F) per 305 m (1000 ft) of altitude above sea-level until a temperature of -56.5°C (-69.7°F) is reached, above which altitude the temperature is considered constant at -56.5°C (-69.7°F). However, for winterization installations, the applicant may select a maximum ambient atmospheric temperature corresponding to sea-level conditions of less than 38°C (100°F).
(c) Correction factor (except cylinder barrels). Unless a more rational correction applies, temperatures of engine fluids and powerplant components (except cylinder barrels) for which temperature limits are established, must be corrected by adding to them the difference between the maximum ambient atmospheric temperature and the temperature of the ambient air at the time of the first occurrence of the maximum component or fluid temperature recorded during the cooling test.
(d) Correction factor for cylinder barrel temperatures. Cylinder barrel temperatures must be corrected by adding to them 0.7 times the difference between the maximum ambient atmospheric temperature and the temperature of the ambient air at the time of the first occurrence of the maximum cylinder barrel temperature recorded during the cooling test.
CS 27.1045 Cooling test procedures
ED Decision 2003/15/RM
(a) General. For each stage of flight, the cooling tests must be conducted with the rotorcraft:
(1) In the configuration most critical for cooling; and
(2) Under the conditions most critical for cooling.
(b) Temperature stabilisation. For the purpose of the cooling tests, a temperature is ‘stabilised’ when its rate of change is less than 1°C (2°F) per minute. The following component and engine fluid temperature stabilisation rules apply:
(1) For each rotorcraft, and for each stage of flight:
(i) The temperatures must be stabilised under the conditions from which entry is made into the stage of flight being investigated; or
(ii) If the entry condition normally does not allow temperatures to stabilise, operation through the full entry condition must be conducted before entry into the stage of flight being investigated in order to allow the temperatures to attain their natural levels at the time of entry.
(2) For each helicopter during the take-off stage of flight the climb at take-off power must be preceded by a period of hover during which the temperatures are stabilised.
(c) Duration of test. For each stage of flight the tests must be continued until:
(1) The temperatures stabilise or 5 minutes after the occurrence of the highest temperature recorded, as appropriate to the test condition;
(2) That stage of flight is completed; or
(3) An operating limitation is reached.
AMC1 27.1045 Cooling test procedures
ED Decision 2023/001/R
(a) Introduction
This AMC supplements FAA AC 27-1B, § AC 27.1045A and should be used in conjunction with that AC when demonstrating compliance with CS 27.1045.
(b) 30-minute power rating
(1) Explanation
This use of this rating may affect the cooling capabilities of the rotorcraft. This potential impact should be evaluated during the certification.
(2) Procedure
In the case of usage of a 30-minute power rating, AC 27.1045A b) should be completed as such:
Procedures. All of the policy material pertaining to this section remains in effect except that the engine fluid temperatures do not have to be stabilised. Paragraph AC 27.1045 currently lists three criteria for test completion: temperature stabilisation, flight test segment completion, or an operation limitation. With Amendment 27-23, a fourth criterion for test completion is:
— 5 minutes after the peak temperature is reached, the test can be considered to be complete, or
— the continuous time limit of the 30-minute power rating if the highest temperature recorded is not stabilised before.
[Amdt 27/10]