209
Federal Aviation Administration, DOT
§ 25.105
associated with the conditions pre-
scribed in §§ 25.119 and 25.121(d) must be
established.
(h) The procedures established under
paragraphs (f) and (g) of this section
must—
(1) Be able to be consistently exe-
cuted in service by crews of average
skill;
(2) Use methods or devices that are
safe and reliable; and
(3) Include allowance for any time
delays, in the execution of the proce-
dures, that may reasonably be expected
in service.
(i) The accelerate-stop and landing
distances prescribed in §§ 25.109 and
25.125, respectively, must be deter-
mined with all the airplane wheel
brake assemblies at the fully worn
limit of their allowable wear range.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–38, 41 FR 55466, Dec. 20,
1976; Amdt. 25–92, 63 FR 8318, Feb. 18, 1998]
§ 25.103
Stall speed.
(a) The reference stall speed, V
SR
, is a
calibrated airspeed defined by the ap-
plicant. V
SR
may not be less than a 1-g
stall speed. V
SR
is expressed as:
V
V
SR
CL
≥
MAX
n
ZW
where:
V
CL
MAX
= Calibrated airspeed obtained when
the load factor-corrected lift coefficient
n
W
qS
ZW
⎛
⎝⎜
⎞
⎠⎟
is first a maximum during the maneuver
prescribed in paragraph (c) of this section. In
addition, when the maneuver is limited by a
device that abruptly pushes the nose down at
a selected angle of attack (e.g., a stick push-
er), V
CL
MAX
may not be less than the speed ex-
isting at the instant the device operates;
n
ZW
= Load factor normal to the flight path
at V
CL
MAX
W = Airplane gross weight;
S = Aerodynamic reference wing area; and
q = Dynamic pressure.
(b) V
CLMAX
is determined with:
(1) Engines idling, or, if that result-
ant thrust causes an appreciable de-
crease in stall speed, not more than
zero thrust at the stall speed;
(2) Propeller pitch controls (if appli-
cable) in the takeoff position;
(3) The airplane in other respects
(such as flaps, landing gear, and ice ac-
cretions) in the condition existing in
the test or performance standard in
which V
SR
is being used;
(4) The weight used when V
SR
is being
used as a factor to determine compli-
ance with a required performance
standard;
(5) The center of gravity position
that results in the highest value of ref-
erence stall speed; and
(6) The airplane trimmed for straight
flight at a speed selected by the appli-
cant, but not less than 1.13V
SR
and not
greater than 1.3V
SR
.
(c) Starting from the stabilized trim
condition, apply the longitudinal con-
trol 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 ref-
erence stall speed, V
SR
, may not be less
than 2 knots or 2 percent, whichever is
greater, above the speed at which the
device operates.
[Doc. No. 28404, 67 FR 70825, Nov. 26, 2002, as
amended by Amdt. 25–121, 72 FR 44665, Aug. 8,
2007]
§ 25.105
Takeoff.
(a) The takeoff speeds prescribed by
§ 25.107, the accelerate-stop distance
prescribed by § 25.109, the takeoff path
prescribed by § 25.111, the takeoff dis-
tance and takeoff run prescribed by
§ 25.113, and the net takeoff flight path
prescribed by § 25.115, must be deter-
mined in the selected configuration for
takeoff at each weight, altitude, and
ambient temperature within the oper-
ational limits selected by the appli-
cant—
(1) In non-icing conditions; and
(2) In icing conditions, if in the con-
figuration used to show compliance
with § 25.121(b), and with the most crit-
ical of the takeoff ice accretion(s) de-
fined in appendices C and O of this
part, as applicable, in accordance with
§ 25.21(g):
(i) The stall speed at maximum take-
off weight exceeds that in non-icing
conditions by more than the greater of
3 knots CAS or 3 percent of V
SR
; or
VerDate Sep<11>2014
09:06 Jun 28, 2024
Jkt 262046
PO 00000
Frm 00219
Fmt 8010
Sfmt 8010
Y:\SGML\262046.XXX
262046
ER26NO02.001</MATH>
ER26NO02.002</MATH>
jspears on DSK121TN23PROD with CFR