378
14 CFR Ch. I (1–1–14 Edition)
§ 25.109
Where—
Tire Pressure=maximum airplane operating
tire pressure (psi);
μ
t/gMAX
=maximum tire-to-ground braking co-
efficient;
V=airplane true ground speed (knots); and
Linear interpolation may be used for tire
pressures other than those listed.
(2) The maximum tire-to-ground wet
runway braking coefficient of friction
must be adjusted to take into account
the efficiency of the anti-skid system
on a wet runway. Anti-skid system op-
eration must be demonstrated by flight
testing on a smooth wet runway, and
its efficiency must be determined. Un-
less a specific anti-skid system effi-
ciency is determined from a quan-
titative analysis of the flight testing
on a smooth wet runway, the max-
imum tire-to-ground wet runway brak-
ing coefficient of friction determined
in paragraph (c)(1) of this section must
be multiplied by the efficiency value
associated with the type of anti-skid
system installed on the airplane:
Type of anti-skid system
Effi-
ciency
value
On-Off ........................................................................
0.30
Quasi-Modulating .......................................................
0.50
Fully Modulating ........................................................
0.80
(d) At the option of the applicant, a
higher wet runway braking coefficient
of friction may be used for runway sur-
faces that have been grooved or treated
with a porous friction course material.
For grooved and porous friction course
runways, the wet runway braking
coefficent of friction is defined as ei-
ther:
(1) 70 percent of the dry runway brak-
ing coefficient of friction used to deter-
mine the dry runway accelerate-stop
distance; or
(2) The wet runway braking coeffi-
cient defined in paragraph (c) of this
section, except that a specific anti-skid
system efficiency, if determined, is ap-
propriate for a grooved or porous fric-
tion course wet runway, and the max-
imum tire-to-ground wet runway brak-
ing coefficient of friction is defined as:
VerDate Mar<15>2010
10:12 Mar 18, 2014
Jkt 232046
PO 00000
Frm 00388
Fmt 8010
Sfmt 8010
Y:\SGML\232046.XXX
232046
ER18FE98.004</GPH>
pmangrum on DSK3VPTVN1PROD with CFR