229 

Federal Aviation Administration, DOT 

§ 25.239 

reasonably expected operating condi-
tion or when rebound occurs during 
landing or takeoff. In addition— 

(1) Wheel brakes must operate 

smoothly and may not cause any undue 
tendency to nose over; and 

(2) If a tail-wheel landing gear is 

used, it must be possible, during the 
takeoff ground run on concrete, to 
maintain any attitude up to thrust line 
level, at 75 percent of 

V

SR1

. 

(b) For seaplanes and amphibians, 

the most adverse water conditions safe 
for takeoff, taxiing, and landing, must 
be established. 

[Doc. No. 5066, 29 FR 18291, Dec. 24, 1964, as 
amended by Amdt. 25–108, 67 FR 70828, Nov. 
26, 2002] 

§ 25.233

Directional stability and con-

trol. 

(a) There may be no uncontrollable 

ground-looping tendency in 90

° 

cross 

winds, up to a wind velocity of 20 knots 
or 0.2 

V

SR0

, whichever is greater, except 

that the wind velocity need not exceed 
25 knots at any speed at which the air-
plane may be expected to be operated 
on the ground. This may be shown 
while establishing the 90

° 

cross compo-

nent of wind velocity required by 
§ 25.237. 

(b) Landplanes must be satisfactorily 

controllable, without exceptional pilot-
ing skill or alertness, in power-off land-
ings at normal landing speed, without 
using brakes or engine power to main-
tain a straight path. This may be 
shown during power-off landings made 
in conjunction with other tests. 

(c) The airplane must have adequate 

directional control during taxiing. This 
may be shown during taxiing prior to 
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 most 

critical of the landing ice accretion(s) 
defined in Appendices C and O of this 
part, as applicable, in accordance with 
§ 25.21(g). 

(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; Amdt. 25–140, 79 FR 65525, Nov. 4, 2014] 

§ 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, 

VerDate Sep<11>2014 

09:06 Jun 28, 2024

Jkt 262046

PO 00000

Frm 00239

Fmt 8010

Sfmt 8010

Y:\SGML\262046.XXX

262046

jspears on DSK121TN23PROD with CFR