JAR 25A1043 Cooling tests
(a) General. Compliance with JAR 25A1041
must be shown by tests under critical ground,
water 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
APU 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) The fuel used during the cooling
tests must be the grade approved for the APUs.
The test procedures must be as prescribed in
JAR 25A1045.
(b) Maximum ambient atmospheric
temperature. A maximum ambient atmospheric
temperature corresponding to sea-level conditions
must be established as a limitation on the
operation of the aeroplane. The temperature lapse
rate is 3·6ºF (2.0ºC) per thousand feet of altitude
above sea-level until a temperature of –69.7ºF
(–56.5ºC) is reached, above which altitude, the
temperature is considered constant at –69.7ºF
(–56.5ºC).
(c) Correction factor. Unless a more
rational correction applies, temperatures of APU
fluids and 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.
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