Section 25.1045

14 CFR Ch. I (1-1-19 Edition)

component or fluid temperature recorded during the cooling test.
(d) Correction factor for cylinder barrel
temperatures. Unless a more rational
correction applies, 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.

spaschal on DSK3GDR082PROD with CFR

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-42, 43 FR 2323, Jan. 16,
1978]

Section 25.1045 Cooling test procedures.
(a) Compliance with Section 25.1041 must be
shown for the takeoff, climb, en route,
and landing stages of flight that correspond to the applicable performance
requirements. The cooling tests must
be conducted with the airplane 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
 - stabilized -  when its rate of change is
less than two degrees F. per minute.
(b) Temperatures must be stabilized
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 the engine fluid temperatures would stabilize (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 takeoff cooling
test must be preceded by a period during which the powerplant component
and engine fluid temperatures are stabilized 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 stabilize;
(2) The stage of flight is completed;
or
(3) An operating limitation is
reached.
(d) For reciprocating engine powered
airplanes, it may be assumed, for cooling test purposes, that the takeoff
stage of flight is complete when the

airplane reaches an altitude of 1,500
feet above the takeoff surface or
reaches a point in the takeoff where
the transition from the takeoff to the
en route configuration is completed
and a speed is reached at which compliance with Section 25.121(c) is shown, whichever point is at a higher altitude. The
airplane must be in the following configuration:
(1) Landing gear retracted.
(2) Wing flaps in the most favorable
position.
(3) Cowl flaps (or other means of controlling the engine cooling supply) in
the position that provides adequate
cooling in the hot-day condition.
(4) Critical engine inoperative and its
propeller stopped.
(5) Remaining engines at the maximum continuous power available for
the altitude.
(e) For hull seaplanes and amphibians, cooling must be shown during
taxiing downwind for 10 minutes, at
five knots above step speed.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-57, 49 FR 6848, Feb. 23,
1984]

INDUCTION SYSTEM
Section 25.1091

Air induction.

(a) The air induction system for each
engine and auxiliary power unit must
supply - 
(1) The air required by that engine
and auxiliary power unit under each
operating condition for which certification is requested; and
(2) The air for proper fuel metering
and mixture distribution with the induction system valves in any position.
(b) Each reciprocating engine must
have an alternate air source that prevents the entry of rain, ice, or any
other foreign matter.
(c) Air intakes may not open within
the cowling, unless - 
(1) That part of the cowling is isolated from the engine accessory section
by means of a fireproof diaphragm; or
(2) For reciprocating engines, there
are means to prevent the emergence of
backfire flames.
(d) For turbine engine powered airplanes and airplanes incorporating auxiliary power units - 

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