395
Federal Aviation Administration, DOT
§ 25.251
takeoffs made in conjunction with
other tests.
[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as
amended by Amdt. 25–23, 35 FR 5671, Apr. 8,
1970; Amdt. 25–42, 43 FR 2322, Jan. 16, 1978;
Amdt. 25–94, 63 FR 8848, Feb. 23, 1998; Amdt.
25–108, 67 FR 70828, Nov. 26, 2002]
§ 25.235
Taxiing condition.
The shock absorbing mechanism may
not damage the structure of the air-
plane when the airplane is taxied on
the roughest ground that may reason-
ably be expected in normal operation.
§ 25.237
Wind velocities.
(a) For land planes and amphibians,
the following applies:
(1) A 90-degree cross component of
wind velocity, demonstrated to be safe
for takeoff and landing, must be estab-
lished for dry runways and must be at
least 20 knots or 0.2 V
SR0
, whichever is
greater, except that it need not exceed
25 knots.
(2) The crosswind component for
takeoff established without ice accre-
tions is valid in icing conditions.
(3) The landing crosswind component
must be established for:
(i) Non-icing conditions, and
(ii) Icing conditions with the landing
ice accretion defined in appendix C.
(b) For seaplanes and amphibians,
the following applies:
(1) A 90-degree cross component of
wind velocity, up to which takeoff and
landing is safe under all water condi-
tions that may reasonably be expected
in normal operation, must be estab-
lished and must be at least 20 knots or
0.2 V
SR0
, whichever is greater, except
that it need not exceed 25 knots.
(2) A wind velocity, for which taxiing
is safe in any direction under all water
conditions that may reasonably be ex-
pected in normal operation, must be es-
tablished and must be at least 20 knots
or 0.2 V
SR0
, whichever is greater, except
that it need not exceed 25 knots.
[Amdt. 25–42, 43 FR 2322, Jan. 16, 1978, as
amended by Amdt. 25–108, 67 FR 70827, Nov.
26, 2002; Amdt. 25–121, 72 FR 44668, Aug. 8,
2007]
§ 25.239
Spray characteristics, control,
and stability on water.
(a) For seaplanes and amphibians,
during takeoff, taxiing, and landing,
and in the conditions set forth in para-
graph (b) of this section, there may be
no—
(1) Spray characteristics that would
impair the pilot’s view, cause damage,
or result in the taking in of an undue
quantity of water;
(2) Dangerously uncontrollable
porpoising, bounding, or swinging tend-
ency; or
(3) Immersion of auxiliary floats or
sponsons, wing tips, propeller blades,
or other parts not designed to with-
stand the resulting water loads.
(b) Compliance with the require-
ments of paragraph (a) of this section
must be shown—
(1) In water conditions, from smooth
to the most adverse condition estab-
lished in accordance with § 25.231;
(2) In wind and cross-wind velocities,
water currents, and associated waves
and swells that may reasonably be ex-
pected in operation on water;
(3) At speeds that may reasonably be
expected in operation on water;
(4) With sudden failure of the critical
engine at any time while on water; and
(5) At each weight and center of grav-
ity position, relevant to each operating
condition, within the range of loading
conditions for which certification is re-
quested.
(c) In the water conditions of para-
graph (b) of this section, and in the
corresponding wind conditions, the sea-
plane or amphibian must be able to
drift for five minutes with engines in-
operative, aided, if necessary, by a sea
anchor.
M
ISCELLANEOUS
F
LIGHT
R
EQUIREMENTS
§ 25.251
Vibration and buffeting.
(a) The airplane must be dem-
onstrated in flight to be free from any
vibration and buffeting that would pre-
vent continued safe flight in any likely
operating condition.
(b) Each part of the airplane must be
demonstrated in flight to be free from
excessive vibration under any appro-
priate speed and power conditions up to
V
DF
/M
DF
. The maximum speeds shown
must be used in establishing the oper-
ating limitations of the airplane in ac-
cordance with § 25.1505.
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