CS 25.1041 General

ED Decision 2003/2/RM

The powerplant cooling provisions must be able to maintain the temperatures of powerplant components, and engine fluids, within the temperature limits established for these components and fluids, under ground and flight operating conditions, and after normal engine shutdown.

CS 25.1043 Cooling tests

ED Decision 2016/010/R

(See AMC 25.1043)

(a) General. Compliance with CS 25.1041 must be shown by tests, under critical ground and flight operating conditions. For these tests, the following apply:

(1) If the tests are conducted under conditions deviating from the maximum ambient atmospheric temperature, the recorded power-plant temperatures must be corrected under sub-paragraph (c) of this paragraph.

(2) No corrected temperatures determined under sub-paragraph (1) of this paragraph may exceed established limits.

(3) Reserved.

(b) Maximum ambient atmospheric temperature. A maximum ambient atmospheric temperature corresponding to sea level conditions of at least 37.8°C (100°F) must be established. The assumed temperature lapse rate is 6.6°C per thousand meter (3·6°F per thousand feet) of altitude above sea level until a temperature of -56.5°C (–69·7°F) is reached, above which altitude the temperature is considered 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 37.8°C (100°F).

(c) Correction factor. Unless a more rational correction applies, temperatures of engine fluids and powerplant components 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.

[Amdt 25/18]

AMC 25.1043 Cooling tests

ED Decision 2014/026/R

In accordance with CS 25.1041, applicants must show that the cooling provisions can maintain the temperatures of powerplant components and engine fluids within the temperature limits for which they have been certified, under ground and flight operating conditions, and after normal engine shutdown.

CS 25.1043(b) establishes 37.8° C (100°F) at sea level as the lowest maximum ambient temperature, except for winterisation installations. Applicants may establish a higher temperature limit if desired.

The assumed temperature lapse rate is 6.6°C per thousand meter (3.6°F per thousand feet) of altitude above sea level until a temperature of -56.5°C (–69.7°F) is reached, above which altitude the temperature is considered at -56.5°C (–69.7°F). The compliance demonstration flight test should be conducted with an ambient temperature as close to the desired maximum ambient atmospheric temperature as practical; the maximum temperature deviation should not normally exceed 13.9°C (25°F). If testing is accomplished at lower ambient temperatures, then the test data must be corrected to that which would have resulted from testing on a day with the maximum ambient atmospheric temperature.

The maximum ambient temperature selected and demonstrated satisfactorily, taking account of correction factors, shall not be less than the minimum hot day conditions prescribed by CS 25.1043(b) and shall be an aeroplane operating limitation per the requirements of CS 25.1521(d). The applicant should correct the engine temperatures to as high a value as possible in order to minimise the impact of this limitation.

[Amdt 25/15]

CS 25.1045 Cooling test procedures

ED Decision 2003/2/RM

(a) Compliance with CS 25.1041 must be shown for the take-off, climb, en-route, and landing stages of flight that correspond to the applicable performance requirements. The cooling tests must be conducted with the aeroplane in the configuration, and operating under the conditions, that are critical relative to cooling during each stage of flight. For the cooling tests, a temperature is ‘stabilised’ when its rate of change is less than 1°C (2°F) per minute.

(b) Temperatures must be stabilised under the conditions from which entry is made into each stage of flight being investigated, unless the entry condition normally is not one during which component and engine fluid temperatures would stabilise (in which case, operation through the full entry condition must be conducted before entry into the stage of flight being investigated in order to allow temperatures to reach their natural levels at the time of entry). The take-off cooling test must be preceded by a period during which the powerplant component and engine fluid temperatures are stabilised with the engines at ground idle.

(c) Cooling tests for each stage of flight must be continued until –

(1) The component and engine fluid temperatures stabilise;

(2) The stage of flight is completed; or

(3) An operating limitation is reached.