title-14-part-25-sec25-1420

356

14 CFR Ch. I (1–1–24 Edition)

§ 25.1420

the various components of the airplane
is adequate, taking into account the
various airplane operational configura-
tions; and

(b) To verify the ice protection anal-

ysis, to check for icing anomalies, and
to demonstrate that the ice protection
system and its components are effec-
tive, the airplane or its components
must be flight tested in the various
operational configurations, in meas-
ured natural atmospheric icing condi-
tions and, as found necessary, by one
or more of the following means:

(1) Laboratory dry air or simulated

icing tests, or a combination of both, of
the components or models of the com-
ponents.

(2) Flight dry air tests of the ice pro-

tection system as a whole, or of its in-
dividual components.

(3) Flight tests of the airplane or its

components in measured simulated
icing conditions.

amber caution light or equivalent,
must be provided to alert the
flightcrew when the anti-ice or de-ice
system is not functioning normally.

(d) For turbine engine powered air-

planes, the ice protection provisions of
this section are considered to be appli-
cable primarily to the airframe. For
the powerplant installation, certain ad-
ditional provisions of subpart E of this
part may be found applicable.

(e) One of the following methods of

icing detection and activation of the
airframe ice protection system must be
provided:

(1) A primary ice detection system

that automatically activates or alerts
the flightcrew to activate the airframe
ice protection system;

(2) A definition of visual cues for rec-

ognition of the first sign of ice accre-
tion on a specified surface combined
with an advisory ice detection system
that alerts the flightcrew to activate
the airframe ice protection system; or

(3) Identification of conditions con-

ducive to airframe icing as defined by
an appropriate static or total air tem-
perature and visible moisture for use
by the flightcrew to activate the air-
frame ice protection system.

(f) Unless the applicant shows that

the airframe ice protection system
need not be operated during specific

phases of flight, the requirements of
paragraph (e) of this section are appli-
cable to all phases of flight.

(g) After the initial activation of the

airframe ice protection system—

(1) The ice protection system must be

designed to operate continuously;

(2) The airplane must be equipped

with a system that automatically cy-
cles the ice protection system; or

(3) An ice detection system must be

provided to alert the flightcrew each
time the ice protection system must be
cycled.

(h) Procedures for operation of the

ice protection system, including acti-
vation and deactivation, must be estab-
lished and documented in the Airplane
Flight Manual.

[Amdt. 25–72, 55 FR 29785, July 20, 1990, as
amended by Amdt. 25–121, 72 FR 44669, Aug. 8,
2007; Amdt. 25–129, 74 FR 38339, Aug. 3, 2009]

§ 25.1420

Supercooled large drop icing

conditions.

(a) If certification for flight in icing

conditions is sought, in addition to the
requirements of § 25.1419, an airplane
with a maximum takeoff weight less
than 60,000 pounds or with reversible
flight controls must be capable of oper-
ating in accordance with paragraphs
(a)(1), (2), or (3), of this section.

(1) Operating safely after encoun-

tering the icing conditions defined in
Appendix O of this part:

(i) The airplane must have a means

to detect that it is operating in Appen-
dix O icing conditions; and

(ii) Following detection of Appendix

O icing conditions, the airplane must
be capable of operating safely while
exiting all icing conditions.

(2) Operating safely in a portion of

the icing conditions defined in Appen-
dix O of this part as selected by the ap-
plicant:

(i) The airplane must have a means

to detect that it is operating in condi-
tions that exceed the selected portion
of Appendix O icing conditions; and

(ii) Following detection, the airplane

must be capable of operating safely
while exiting all icing conditions.

(3) Operating safely in the icing con-

ditions defined in Appendix O of this
part.

(b) To establish that the airplane can

operate safely as required in paragraph

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§ 25.1423

(a) of this section, an applicant must
show through analysis that the ice pro-
tection for the various components of
the airplane is adequate, taking into
account the various airplane oper-
ational configurations. To verify the
analysis, one, or more as found nec-
essary, of the following methods must
be used:

(1) Laboratory dry air or simulated

icing tests, or a combination of both, of
the components or models of the com-
ponents.

(2) Laboratory dry air or simulated

icing tests, or a combination of both, of
models of the airplane.

(3) Flight tests of the airplane or its

components in simulated icing condi-
tions, measured as necessary to sup-
port the analysis.

(4) Flight tests of the airplane with

simulated ice shapes.

(5) Flight tests of the airplane in nat-

ural icing conditions, measured as nec-
essary to support the analysis.

cordance with paragraph (a)(2) or (3) of
this section, the requirements of
§ 25.1419(e), (f), (g), and (h) must be met
for the icing conditions defined in Ap-
pendix O of this part in which the air-
plane is certified to operate.

(d) For the purposes of this section,

the following definitions apply:

(1)

Reversible Flight Controls. Flight

controls in the normal operating con-
figuration that have force or motion
originating at the airplane’s control
surface (for example, through aero-
dynamic loads, static imbalance, or
trim or servo tab inputs) that is trans-
mitted back to flight deck controls.
This term refers to flight deck controls
connected to the pitch, roll, or yaw
control surfaces by direct mechanical
linkages, cables, or push-pull rods in
such a way that pilot effort produces
motion or force about the hinge line.

(2)

Simulated Icing Test. Testing con-

ducted in simulated icing conditions,
such as in an icing tunnel or behind an
icing tanker.

(3)

Simulated Ice Shape. Ice shape fab-

ricated from wood, epoxy, or other ma-
terials by any construction technique.

[Amdt. 25–140, 79 FR 65528, Nov. 4, 2014]

§ 25.1421

Megaphones.

If a megaphone is installed, a re-

straining means must be provided that
is capable of restraining the mega-
phone when it is subjected to the ulti-
mate inertia forces specified in
§ 25.561(b)(3).

[Amdt. 25–41, 42 FR 36970, July 18, 1977]

§ 25.1423

Public address system.

A public address system required by

this chapter must—

(a) Be powerable when the aircraft is

in flight or stopped on the ground,
after the shutdown or failure of all en-
gines and auxiliary power units, or the
disconnection or failure of all power
sources dependent on their continued
operation, for—

(1) A time duration of at least 10 min-

utes, including an aggregate time dura-
tion of at least 5 minutes of announce-
ments made by flight and cabin crew-
members, considering all other loads
which may remain powered by the
same source when all other power
sources are inoperative; and

(2) An additional time duration in its

standby state appropriate or required
for any other loads that are powered by
the same source and that are essential
to safety of flight or required during
emergency conditions.

(b) Be capable of operation within 3

seconds from the time a microphone is
removed from its stowage.

seats, lavatories, and flight attendant
seats and work stations.

(d) Be designed so that no unused,

unstowed microphone will render the
system inoperative.

(e) Be capable of functioning inde-

pendently of any required crewmember
interphone system.

(f) Be accessible for immediate use

from each of two flight crewmember
stations in the pilot compartment.

(g) For each required floor-level pas-

senger emergency exit which has an ad-
jacent flight attendant seat, have a
microphone which is readily accessible
to the seated flight attendant, except
that one microphone may serve more
than one exit, provided the proximity
of the exits allows unassisted verbal