title-14-part-25-sec25-1443

360

14 CFR Ch. I (1–1–24 Edition)

§ 25.1441

volume of 30 liters per minute BTPD.
The equipment and system must be de-
signed to prevent any inward leakage
to the inside of the device and prevent
any outward leakage causing signifi-
cant increase in the oxygen content of
the local ambient atmosphere. If a de-
mand oxygen system is used, a supply
of 300 liters of free oxygen at 70

F. and

760 mm. Hg. pressure is considered to
be of 15-minute duration at the pre-
scribed altitude and minute volume. If
a continuous flow open circuit protec-
tive breathing system is used, a flow
rate of 60 liters per minute at 8,000 feet
(45 liters per minute at sea level) and a
supply of 600 liters of free oxygen at 70

F. and 760 mm. Hg. pressure is consid-

ered to be of 15-minute duration at the
prescribed altitude and minute volume.
Continuous flow systems must not in-
crease the ambient oxygen content of
the local atmosphere above that of de-
mand systems. BTPD refers to body
temperature conditions (that is, 37

C.,

at ambient pressure, dry).

(6) The equipment must meet the re-

quirements of § 25.1441.

[Doc. No. FAA–2002–13859, 69 FR 40528, July 2,
2004]

§ 25.1441

Oxygen equipment and sup-

ply.

(a) If certification with supplemental

oxygen equipment is requested, the
equipment must meet the requirements
of this section and §§ 25.1443 through
25.1453.

(b) The oxygen system must be free

from hazards in itself, in its method of
operation, and in its effect upon other
components.

the crew to readily determine, during
flight, the quantity of oxygen available
in each source of supply.

(d) The oxygen flow rate and the oxy-

gen equipment for airplanes for which
certification for operation above 40,000
feet is requested must be approved.

§ 25.1443

Minimum mass flow of sup-

plemental oxygen.

(a) If continuous flow equipment is

installed for use by flight crew-
members, the minimum mass flow of
supplemental oxygen required for each
crewmember may not be less than the
flow required to maintain, during in-

spiration, a mean tracheal oxygen par-
tial pressure of 149 mm. Hg. when
breathing 15 liters per minute, BTPS,
and with a maximum tidal volume of
700 cc. with a constant time interval
between respirations.

(b) If demand equipment is installed

for use by flight crewmembers, the
minimum mass flow of supplemental
oxygen required for each crewmember
may not be less than the flow required
to maintain, during inspiration, a
mean tracheal oxygen partial pressure
of 122 mm. Hg., up to and including a
cabin pressure altitude of 35,000 feet,
and 95 percent oxygen between cabin
pressure altitudes of 35,000 and 40,000
feet, when breathing 20 liters per
minute BTPS. In addition, there must
be means to allow the crew to use undi-
luted oxygen at their discretion.

ants, the minimum mass flow of sup-
plemental oxygen required for each
person at various cabin pressure alti-
tudes may not be less than the flow re-
quired to maintain, during inspiration
and while using the oxygen equipment
(including masks) provided, the fol-
lowing mean tracheal oxygen partial
pressures:

(1) At cabin pressure altitudes above

10,000 feet up to and including 18,500
feet, a mean tracheal oxygen partial
pressure of 100 mm. Hg. when breathing
15 liters per minute, BTPS, and with a
tidal volume of 700 cc. with a constant
time interval between respirations.

(2) At cabin pressure altitudes above

18,500 feet up to and including 40,000
feet, a mean tracheal oxygen partial
pressure of 83.8 mm. Hg. when breath-
ing 30 liters per minute, BTPS, and
with a tidal volume of 1,100 cc. with a
constant time interval between res-
pirations.

(d) If first-aid oxygen equipment is

installed, the minimum mass flow of
oxygen to each user may not be less
than four liters per minute, STPD.
However, there may be a means to de-
crease this flow to not less than two li-
ters per minute, STPD, at any cabin al-
titude. The quantity of oxygen re-
quired is based upon an average flow
rate of three liters per minute per per-
son for whom first-aid oxygen is re-
quired.

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§ 25.1447

(e) If portable oxygen equipment is

installed for use by crewmembers, the
minimum mass flow of supplemental
oxygen is the same as specified in para-
graph (a) or (b) of this section, which-
ever is applicable.

§ 25.1445

Equipment standards for the

oxygen distributing system.

(a) When oxygen is supplied to both

crew and passengers, the distribution
system must be designed for either—

(1) A source of supply for the flight

crew on duty and a separate source for
the passengers and other crewmembers;
or

(2) A common source of supply with

means to separately reserve the min-
imum supply required by the flight
crew on duty.

(b) Portable walk-around oxygen

units of the continuous flow, diluter-
demand, and straight demand kinds
may be used to meet the crew or pas-
senger breathing requirements.

§ 25.1447

Equipment standards for ox-

ygen dispensing units.

If oxygen dispensing units are in-

stalled, the following apply:

(a) There must be an individual dis-

pensing unit for each occupant for
whom supplemental oxygen is to be
supplied. Units must be designed to
cover the nose and mouth and must be
equipped with a suitable means to re-
tain the unit in position on the face.
Flight crew masks for supplemental
oxygen must have provisions for the
use of communication equipment.

(b) If certification for operation up to

and including 25,000 feet is requested,
an oxygen supply terminal and unit of
oxygen dispensing equipment for the
immediate use of oxygen by each crew-
member must be within easy reach of
that crewmember. For any other occu-
pants, the supply terminals and dis-
pensing equipment must be located to
allow the use of oxygen as required by
the operating rules in this chapter.

above 25,000 feet is requested, there
must be oxygen dispensing equipment
meeting the following requirements:

(1) There must be an oxygen dis-

pensing unit connected to oxygen sup-
ply terminals immediately available to
each occupant wherever seated, and at

least two oxygen dispensing units con-
nected to oxygen terminals in each lav-
atory. The total number of dispensing
units and outlets in the cabin must ex-
ceed the number of seats by at least 10
percent. The extra units must be as
uniformly distributed throughout the
cabin as practicable. Except as pro-
vided in paragraph (c)(5) of this sec-
tion, if certification for operation
above 30,000 feet is requested, the dis-
pensing units providing the required
oxygen flow must be automatically
presented to the occupants before the
cabin pressure altitude exceeds 15,000
feet. The crewmembers must be pro-
vided with a manual means of making
the dispensing units immediately
available in the event of failure of the
automatic system.

(2) Each flight crewmember on flight

deck duty must be provided with a
quick-donning type oxygen dispensing
unit connected to an oxygen supply
terminal. This dispensing unit must be
immediately available to the flight
crewmember when seated at his sta-
tion, and installed so that it:

(i) Can be placed on the face from its

ready position, properly secured,
sealed, and supplying oxygen upon de-
mand, with one hand, within five sec-
onds and without disturbing eyeglasses
or causing delay in proceeding with
emergency duties; and

(ii) Allows, while in place, the per-

formance of normal communication
functions.

(3) The oxygen dispensing equipment

for the flight crewmembers must be:

(i) The diluter demand or pressure de-

mand (pressure demand mask with a
diluter demand pressure breathing reg-
ulator) type, or other approved oxygen
equipment shown to provide the same
degree of protection, for airplanes to be
operated above 25,000 feet.

(ii) The pressure demand (pressure

demand mask with a diluter demand
pressure breathing regulator) type with
mask-mounted regulator, or other ap-
proved oxygen equipment shown to
provide the same degree of protection,
for airplanes operated at altitudes
where decompressions that are not ex-
tremely improbable may expose the
flightcrew to cabin pressure altitudes
in excess of 34,000 feet.