Section 25.27

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

compliance with each applicable requirement of this part is shown) must
be established so that it is not less
than - 
(1) The lowest weight selected by the
applicant;
(2) The design minimum weight (the
lowest weight at which compliance
with each structural loading condition
of this part is shown); or
(3) The lowest weight at which compliance with each applicable flight requirement is shown.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-23, 35 FR 5671, Apr. 8,
1970; Amdt. 25-63, 53 FR 16365, May 6, 1988]

Section 25.27

Center of gravity limits.

The extreme forward and the extreme
aft center of gravity limitations must
be established for each practicably separable operating condition. No such
limit may lie beyond - 
(a) The extremes selected by the applicant;
(b) The extremes within which the
structure is proven; or
(c) The extremes within which compliance with each applicable flight requirement is shown.
Section 25.29 Empty
weight
and
responding center of gravity.

cor-

spaschal on DSK3GDR082PROD with CFR

(a) The empty weight and corresponding center of gravity must be
determined by weighing the airplane
with - 
(1) Fixed ballast;
(2) Unusable fuel determined under
Section 25.959; and
(3) Full operating fluids, including - 
(i) Oil;
(ii) Hydraulic fluid; and
(iii) Other fluids required for normal
operation of airplane systems, except
potable water, lavatory precharge
water, and fluids intended for injection
in the engine.
(b) The condition of the airplane at
the time of determining empty weight
must be one that is well defined and
can be easily repeated.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-42, 43 FR 2320, Jan. 16,
1978; Amdt. 25-72, 55 FR 29774, July 20, 1990]

Section 25.31 Removable ballast.
Removable ballast may be used on
showing compliance with the flight requirements of this subpart.
Section 25.33 Propeller speed and pitch limits.
(a) The propeller speed and pitch
must be limited to values that will ensure - 
(1) Safe operation under normal operating conditions; and
(2) Compliance with the performance
requirements of SectionSection 25.101 through 25.125.
(b) There must be a propeller speed
limiting means at the governor. It
must limit the maximum possible governed engine speed to a value not exceeding the maximum allowable r.p.m.
(c) The means used to limit the low
pitch position of the propeller blades
must be set so that the engine does not
exceed 103 percent of the maximum allowable engine rpm or 99 percent of an
approved maximum overspeed, whichever is greater, with - 
(1) The propeller blades at the low
pitch limit and governor inoperative;
(2) The airplane stationary under
standard atmospheric conditions with
no wind; and
(3) The engines operating at the takeoff manifold pressure limit for reciprocating engine powered airplanes or the
maximum takeoff torque limit for turbopropeller engine-powered airplanes.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-57, 49 FR 6848, Feb. 23,
1984; Amdt. 25-72, 55 FR 29774, July 20, 1990]

PERFORMANCE
Section 25.101 General.
(a) Unless otherwise prescribed, airplanes must meet the applicable performance requirements of this subpart
for ambient atmospheric conditions
and still air.
(b) The performance, as affected by
engine power or thrust, must be based
on the following relative humidities;
(1) For turbine engine powered airplanes, a relative humidity of - 
(i) 80 percent, at and below standard
temperatures; and
(ii) 34 percent, at and above standard
temperatures plus 50 SectionF.
Between these two temperatures, the
relative humidity must vary linearly.

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