Section 25.105

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

(3) The airplane in other respects
(such as flaps, landing gear, and ice accretions) in the condition existing in
the test or performance standard in
which VSR is being used;
(4) The weight used when VSR is being
used as a factor to determine compliance with a required performance
standard;
(5) The center of gravity position
that results in the highest value of reference stall speed; and
(6) The airplane trimmed for straight
flight at a speed selected by the applicant, but not less than 1.13VSR and not
greater than 1.3VSR.
(c) Starting from the stabilized trim
condition, apply the longitudinal control to decelerate the airplane so that
the speed reduction does not exceed
one knot per second.
(d) In addition to the requirements of
paragraph (a) of this section, when a
device that abruptly pushes the nose
down at a selected angle of attack (e.g.,
a stick pusher) is installed, the reference stall speed, VSR, may not be less
than 2 knots or 2 percent, whichever is
greater, above the speed at which the
device operates.

spaschal on DSK3GDR082PROD with CFR

[Doc. No. 28404, 67 FR 70825, Nov. 26, 2002, as
amended by Amdt. 25-121, 72 FR 44665, Aug. 8,
2007]

Section 25.105 Takeoff.
(a) The takeoff speeds prescribed by
Section 25.107, the accelerate-stop distance
prescribed by Section 25.109, the takeoff path
prescribed by Section 25.111, the takeoff distance and takeoff run prescribed by
Section 25.113, and the net takeoff flight path
prescribed by Section 25.115, must be determined in the selected configuration for
takeoff at each weight, altitude, and
ambient temperature within the operational limits selected by the applicant - 
(1) In non-icing conditions; and
(2) In icing conditions, if in the configuration used to show compliance
with Section 25.121(b), and with the most critical of the takeoff ice accretion(s) defined in appendices C and O of this
part, as applicable, in accordance with
Section 25.21(g):
(i) The stall speed at maximum takeoff weight exceeds that in non-icing
conditions by more than the greater of
3 knots CAS or 3 percent of VSR; or

(ii) The degradation of the gradient
of climb determined in accordance with
Section 25.121(b) is greater than one-half of
the applicable actual-to-net takeoff
flight path gradient reduction defined
in Section 25.115(b).
(b) No takeoff made to determine the
data required by this section may require exceptional piloting skill or
alertness.
(c) The takeoff data must be based
on - 
(1) In the case of land planes and amphibians:
(i) Smooth, dry and wet, hard-surfaced runways; and
(ii) At the option of the applicant,
grooved or porous friction course wet,
hard-surfaced runways.
(2) Smooth water, in the case of seaplanes and amphibians; and
(3) Smooth, dry snow, in the case of
skiplanes.
(d) The takeoff data must include,
within the established operational limits of the airplane, the following operational correction factors:
(1) Not more than 50 percent of nominal wind components along the takeoff
path opposite to the direction of takeoff, and not less than 150 percent of
nominal wind components along the
takeoff path in the direction of takeoff.
(2) Effective runway gradients.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25-92, 63 FR 8318, Feb. 18,
1998; Amdt. 25-121, 72 FR 44665, Aug. 8, 2007;
Amdt. 25-140, 79 FR 65525, Nov. 4, 2014]

Section 25.107 Takeoff speeds.
(a) V1 must be established in relation
to VEF as follows:
(1) VEF is the calibrated airspeed at
which the critical engine is assumed to
fail. VEF must be selected by the applicant, but may not be less than VMCG determined under Section 25.149(e).
(2) V1, in terms of calibrated airspeed, is selected by the applicant;
however, V1 may not be less than VEF
plus the speed gained with critical engine inoperative during the time interval between the instant at which the
critical engine is failed, and the instant at which the pilot recognizes and
reacts to the engine failure, as indicated by the pilot-s initiation of the
first action (e.g., applying brakes, reducing thrust, deploying speed brakes)

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