spaschal on DSK3GDR082PROD with CFR

Section 25.1457

14 CFR Ch. I (1-1-19 Edition)

position for recording voice communications originating at the first and
second pilot stations and voice communications of other crewmembers on the
flight deck when directed to those stations. The microphone must be so located and, if necessary, the preamplifiers and filters of the recorder
must be so adjusted or supplemented,
that the intelligibility of the recorded
communications is as high as practicable when recorded under flight
cockpit noise conditions and played
back. Repeated aural or visual playback of the record may be used in evaluating intelligibility.
(c) Each cockpit voice recorder must
be installed so that the part of the
communication or audio signals specified in paragraph (a) of this section obtained from each of the following
sources is recorded on a separate channel:
(1) For the first channel, from each
boom, mask, or hand-held microphone,
headset, or speaker used at the first
pilot station.
(2) For the second channel from each
boom, mask, or hand-held microphone,
headset, or speaker used at the second
pilot station.
(3) For the third channel - from the
cockpit-mounted area microphone.
(4) For the fourth channel, from - 
(i) Each boom, mask, or hand-held
microphone, headset, or speaker used
at the station for the third and fourth
crew members; or
(ii) If the stations specified in paragraph (c)(4)(i) of this section are not required or if the signal at such a station
is picked up by another channel, each
microphone on the flight deck that is
used with the passenger loudspeaker
system, if its signals are not picked up
by another channel.
(5) As far as is practicable all sounds
received by the microphone listed in
paragraphs (c)(1), (2), and (4) of this
section must be recorded without
interruption irrespective of the position of the interphone-transmitter key
switch. The design shall ensure that
sidetone for the flight crew is produced
only when the interphone, public address system, or radio transmitters are
in use.
(d) Each cockpit voice recorder must
be installed so that - 

(1)(i) It receives its electrical power
from the bus that provides the maximum reliability for operation of the
cockpit voice recorder without jeopardizing service to essential or emergency
loads.
(ii) It remains powered for as long as
possible without jeopardizing emergency operation of the airplane.
(2) There is an automatic means to
simultaneously stop the recorder and
prevent each erasure feature from functioning, within 10 minutes after crash
impact;
(3) There is an aural or visual means
for preflight checking of the recorder
for proper operation;
(4) Any single electrical failure external to the recorder does not disable
both the cockpit voice recorder and the
flight data recorder;
(5) It has an independent power
source - 
(i) That provides 10 Section1 minutes of
electrical power to operate both the
cockpit voice recorder and cockpitmounted area microphone;
(ii) That is located as close as practicable to the cockpit voice recorder;
and
(iii) To which the cockpit voice recorder and cockpit-mounted area
microphone are switched automatically in the event that all other power
to the cockpit voice recorder is interrupted either by normal shutdown or
by any other loss of power to the electrical power bus; and
(6) It is in a separate container from
the flight data recorder when both are
required. If used to comply with only
the cockpit voice recorder requirements, a combination unit may be installed.
(e) The recorder container must be
located and mounted to minimize the
probability of rupture of the container
as a result of crash impact and consequent heat damage to the recorder
from fire.
(1) Except as provided in paragraph
(e)(2) of this section, the recorder container must be located as far aft as
practicable, but need not be outside of
the pressurized compartment, and may
not be located where aft-mounted engines may crush the container during
impact.

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