Document ID: FAA-2023-2251-0001
Agency: faa
Document Type: Proposed Rule
Title: Special Conditions: Aerocon Engineering Company, Airbus Model A330–300 Series Airplane; Lower Deck Crew Rest Compartment Installation
Posted Date: 2023-12-13T05:00Z

[Federal Register Volume 88, Number 238 (Wednesday, December 13, 2023)]
[Proposed Rules]
[Pages 86274-86278]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2023-27396]

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 Proposed Rules
                                                 Federal Register
 ________________________________________________________________________
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 This section of the FEDERAL REGISTER contains notices to the public of 
 the proposed issuance of rules and regulations. The purpose of these 
 notices is to give interested persons an opportunity to participate in 
 the rule making prior to the adoption of the final rules.
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  Federal Register / Vol. 88, No. 238 / Wednesday, December 13, 2023 / 
Proposed Rules  

[[Page 86274]]

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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. FAA-2023-2251; Notice No. 25-23-05-SC]

Special Conditions: Aerocon Engineering Company, Airbus Model 
A330-300 Series Airplane; Lower Deck Crew Rest Compartment Installation

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Notice of proposed special conditions.

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SUMMARY: This action proposes special conditions for the Airbus Model 
A330-300 series airplane. This airplane as modified by Aerocon 
Engineering Company (Aerocon) will have a novel or unusual design 
feature when compared to the state of technology envisioned in the 
airworthiness standards for transport category airplanes. This design 
feature is an installation of a lower deck crew rest compartment 
(LDCRC) under the passenger cabin floor in the cargo compartment. The 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for this design feature. These proposed 
special conditions contain the additional safety standards that the 
Administrator considers necessary to establish a level of safety 
equivalent to that established by the existing airworthiness standards.

DATES: Send comments on or before January 29, 2024.

ADDRESSES: Send comments identified by Docket No. FAA-2023-2251 using 
any of the following methods:
    Federal eRegulations Portal: Go to www.regulations.gov and follow 
the online instructions for sending your comments electronically.
    Mail: Send comments to Docket Operations, M-30, U.S. Department of 
Transportation (DOT), 1200 New Jersey Avenue SE, Room W12-140, West 
Building Ground Floor, Washington, DC 20590-0001.
    Hand Delivery or Courier: Take comments to Docket Operations in 
Room W12-140 of the West Building Ground Floor at 1200 New Jersey 
Avenue SE, Washington, DC, between 9 a.m. and 5 p.m., Monday through 
Friday, except Federal holidays.
    Fax: Fax comments to Docket Operations at 202-493-2251.
    Docket: Background documents or comments received may be read at 
www.regulations.gov at any time. Follow the online instructions for 
accessing the docket or go to Docket Operations in Room W12-140 of the 
West Building Ground Floor at 1200 New Jersey Avenue SE, Washington, 
DC, between 9 a.m. and 5 p.m., Monday through Friday, except Federal 
holidays.

FOR FURTHER INFORMATION CONTACT: Daniel Jacquet, Cabin Safety, AIR-624, 
Technical Policy Branch, Policy and Standards Division, Aircraft 
Certification Service, Federal Aviation Administration, 2200 South 
216th Street, Des Moines, Washington 98198; telephone and fax (206) 
231-3208; email [email protected].

SUPPLEMENTARY INFORMATION:

Comments Invited

    The FAA invites interested people to take part in this rulemaking 
by sending written comments, data, or views. The most helpful comments 
reference a specific portion of the proposed special conditions, 
explain the reason for any recommended change, and include supporting 
data.
    The FAA will consider all comments received by the closing date for 
comments and will consider comments filed late if it is possible to do 
so without incurring delay. The FAA may change these special conditions 
based on the comments received.

Privacy

    Except for Confidential Business Information (CBI) as described in 
the following paragraph, and other information as described in title 
14, Code of Federal Regulations (14 CFR) 11.35, the FAA will post all 
comments received without change to www.regulations.gov, including any 
personal information, you provide. The FAA will also post a report 
summarizing each substantive verbal contact received about these 
special conditions.

Confidential Business Information

    Confidential Business Information (CBI) is commercial or financial 
information that is both customarily and actually treated as private by 
its owner. Under the Freedom of Information Act (FOIA) (5 U.S.C. 552), 
CBI is exempt from public disclosure. If your comments responsive to 
these special conditions contain commercial or financial information 
that is customarily treated as private, that you actually treat as 
private, and that is relevant or responsive to these special 
conditions, it is important that you clearly designate the submitted 
comments as CBI. Please mark each page of your submission containing 
CBI as ``PROPIN.'' The FAA will treat such marked submissions as 
confidential under the FOIA, and the indicated comments will not be 
placed in the public docket of these special conditions. Send 
submissions containing CBI to the individual listed in the For Further 
Information Contact section. Comments the FAA receives, which are not 
specifically designated as CBI, will be placed in the public docket for 
these special conditions.

Background

    On July 5, 2022, Aerocon applied for a supplemental type 
certificate for the installation of a LDCRC in the Airbus Model A330-
300 series airplane. The Airbus Model A330-300 series airplane is a 
twin-engine, transport-category airplane with a maximum takeoff weight 
of 533,518 pounds and maximum seating for 440 passengers.

Type Certification Basis

    Under the provisions of 14 CFR 21.101, Aerocon must show that the 
Airbus Model A330-300 series airplane, as changed, continues to meet 
the applicable provisions of the regulations listed in Type Certificate 
No. A46NM or the applicable regulations in effect on the date of 
application for the change, except for earlier amendments as agreed 
upon by the FAA.
    If the Administrator finds that the applicable airworthiness 
regulations (e.g., 14 CFR part 25) do not contain adequate or 
appropriate safety standards for the Airbus Model A330-300 series 
airplane because of a novel or unusual design feature, special 
conditions are

[[Page 86275]]

prescribed under the provisions of Sec.  21.16.
    Should the applicant apply for a supplemental type certificate to 
modify any other model included on the same type certificate to 
incorporate the same novel or unusual design feature, these special 
conditions would also apply to the other model under Sec.  21.101.
    In addition to the applicable airworthiness regulations and special 
conditions, the Airbus Model A330-300 series airplane must comply with 
the fuel-vent and exhaust-emission requirements of 14 CFR part 34, and 
the noise-certification requirements of 14 CFR part 36.
    The FAA issues special conditions, as defined in 14 CFR 11.19, in 
accordance with Sec.  11.38, and they become part of the type 
certification basis under Sec.  21.101.

Novel or Unusual Design Features

    The Airbus Model A330-300 series airplane will incorporate the 
following novel or unusual design feature:
    Installation of a LDCRC under the passenger cabin floor in the 
cargo compartment.

Discussion

    Section 25.819 applies to lower deck service compartments 
(including galleys) but is not directly applicable to LDCRC. The 
applicable airworthiness regulations do not contain adequate or 
appropriate safety standards for this design feature. Special 
conditions are required for the certification of the LDCRC to 
supplement part 25.
    The LDCRC will be located under the passenger cabin floor in the 
cargo compartment of the Airbus A330-330 model series airplane. It will 
be removable from the cargo compartment. Occupancy of the LDCRC will be 
limited to a maximum of eight crew members, and it will only be 
occupied in flight, i.e., not during taxi, takeoff, or landing. A smoke 
detection system, fire extinguishing system, oxygen system, and 
occupant amenities will be provided.
    The LDCRC will be accessed from the main deck via a stair house. 
The floor within the stair house has an access hatch that leads to 
stairs, which occupants use to descend into the LDCRC. This hatch locks 
automatically in the open position when fully opened. In addition, 
there will be an emergency hatch, which opens directly into the main 
passenger cabin area. The LDCRC also has a maintenance access/ground 
loading door, which allows access to and from the cargo compartment. 
The intended use of this door is to allow cargo loading and maintenance 
personnel to enter the LDCRC from the cargo compartment when the 
airplane is on the ground, and not moving.
    The proposed special conditions contain the additional safety 
standards that the Administrator considers necessary to establish a 
level of safety equivalent to that established by the existing 
airworthiness standards.

Applicability

    As discussed above, these proposed special conditions are 
applicable to the Airbus Model A330-300 series airplane for which they 
are issued. Should the applicant apply for a supplemental type 
certificate to modify any other model included on the same type 
certificate to incorporate the same novel or unusual design feature, 
these special conditions would apply to the other model as well.

Conclusion

    This action affects only certain novel or unusual design feature on 
one model A330-300 airplane. It is not a rule of general applicability 
and affects only the applicant who applied to the FAA for approval of 
these features on the airplane.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

Authority Citation

    The authority citation for these special conditions is as follows:

    Authority: 49 U.S.C. 106(f), 106(g), 40113, 44701, 44702, and 
44704.

The Proposed Special Conditions

    Accordingly, the Federal Aviation Administration (FAA) proposes the 
following special conditions as part of the type certification basis 
for Airbus Model A330-300 series airplanes as modified by Aerocon 
Engineering Company.
    (a) Occupancy of the LDCRC is limited to a maximum of eight. There 
must be an approved seat or berth able to withstand the maximum flight 
loads when occupied for each occupant permitted in the crew rest 
compartment.
    (1) There must be appropriate placards displayed in a conspicuous 
place at each entrance to the LDCRC compartment to indicate:
    (i) The maximum number of occupants allowed.
    (ii) That occupancy is restricted to crewmembers that are trained 
in the evacuation procedures for the crew rest compartment.
    (iii) That occupancy is prohibited during taxi, take-off, and 
landing.
    (iv) That smoking is prohibited in the crew rest compartment.
    (v) That hazardous quantity of flammable fluids, explosives, or 
other dangerous cargo is prohibited from the crew rest compartment.
    (vi) That the crew rest area must be limited to the stowage of crew 
personal luggage and must not be used for the stowage of cargo or 
passenger baggage.
    (2) There must be at least one ashtray located conspicuously on or 
near the entry side of any entrance, usable in-flight, to the crew rest 
compartment.
    (3) There must be a means to prevent passengers from entering the 
compartment in the event of an emergency or when no flight attendant is 
present.
    (4) There must be a means for any door installed between the crew 
rest compartment and passenger cabin to be capable of being quickly 
opened from inside the compartment, even when crowding occurs at each 
side of the door.
    (5) For all doors installed in the evacuation routes, there must be 
a means to preclude anyone from being trapped inside the compartment. 
If a locking mechanism is installed, it must be capable of being 
unlocked from the outside without the aid of special tools. The lock 
must not prevent opening from the inside of the compartment at any 
time.
    (b) There must be at least two emergency evacuation routes, which 
could be used by each occupant of the crew rest compartment to rapidly 
evacuate to the main cabin and be able to be closed from the main 
passenger cabin after evacuation. In addition--
    (1) The routes must be located with one at each end of the 
compartment, or with two having sufficient separation within the 
compartment and between the routes to minimize the possibility of an 
event (either inside or outside of the crew rest compartment) rendering 
both routes inoperative.
    (2) The routes must be designed to minimize the possibility of 
blockage, which might result from fire, mechanical or structural 
failure, or persons standing on top of or against the escape route. If 
an evacuation route utilizes an area where normal movement of 
passengers occurs, it must be demonstrated that passengers would not 
impede egress to the main deck. If a hatch is installed in an 
evacuation route, the point at which the evacuation route terminates in 
the passenger cabin should not be located where normal movement by 
passengers or crew occurs (main aisle, cross aisle, passageway or 
galley complex). If such a location cannot be avoided, special 
consideration must be taken to ensure that the hatch or door can be 
opened

[[Page 86276]]

when a person, the weight of a ninety-fifth percentile male, is 
standing on the hatch or door. The use of evacuation routes must not be 
dependent on any powered device. If there is low headroom at or near an 
evacuation route, provisions must be made to prevent or to protect 
occupants of the crew rest area from head injury.
    (3) Emergency evacuation procedures, including the emergency 
evacuation of an incapacitated occupant from the crew rest compartment, 
must be established. All of these procedures must be transmitted to the 
operator for incorporation into their training programs and appropriate 
operational manuals.
    (4) There must be a limitation in the airplane flight manual or 
other suitable means requiring that crewmembers be trained in the use 
of evacuation routes.
    (c) There must be a means for the evacuation of an incapacitated 
person (representative of a 95th percentile male) from the crew rest 
compartment to the passenger cabin floor.
    The evacuation must be demonstrated for all evacuation routes. A 
flight attendant or other crewmember (a total of one assistant within 
the crew rest area) may provide assistance in the evacuation. 
Additional assistance may be provided by up to three persons in the 
main passenger compartment. For evacuation routes having stairways, the 
additional assistants may descend down to one half the elevation change 
from the main deck to the lower deck compartment, or to the first 
landing, whichever is higher.
    (d) The following signs and placards must be provided in the crew 
rest compartment:
    (1) At least one exit sign, located near each exit, meeting the 
requirements of Sec.  25.812(b)(1)(i) at Amendment 25-58, except that a 
sign with reduced background area of no less than 5.3 square inches 
(excluding the letters) may be utilized, provided that it is installed 
such that the material surrounding the exit sign is light in color 
(e.g., white, cream, light beige). If the material surrounding the exit 
sign is not light in color, a sign with a minimum of a one-inch wide 
background border around the letters would also be acceptable.
    (2) An appropriate placard located near each exit defining the 
location and the operating instructions for each evacuation route.
    (3) Placards must be readable from a distance of 30 inches under 
emergency lighting conditions.
    (4) The exit handles and evacuation path operating instruction 
placards must be illuminated to at least 160 micro lamberts under 
emergency lighting conditions.
    (e) There must be a means in the event of failure of the aircraft's 
main power system, or of the normal crew rest compartment lighting 
system, for emergency illumination to be automatically provided for the 
crew rest compartment.
    (1) This emergency illumination must be independent of the main 
lighting system.
    (2) The sources of general cabin illumination may be common to both 
the emergency and the main lighting systems if the power supply to the 
emergency lighting system is independent of the power supply to the 
main lighting system.
    (3) The illumination level must be sufficient for the occupants of 
the crew rest compartment to locate and transfer to the main passenger 
cabin floor by means of each evacuation route.
    (4) The illumination level must be sufficient with the privacy 
curtains in the closed position for each occupant of the crew rest to 
locate a deployed oxygen mask.
    (f) There must be means for two-way voice communications between 
crewmembers on the flight deck and occupants of the crew rest 
compartment. There must also be public address (PA) system microphones 
at each flight attendant seat required to be near a floor level exit in 
the passenger cabin per Sec.  25.785(h) at Amendment 25-51. The PA 
system must allow two-way voice communications between flight 
attendants and the occupants of the crew rest compartment, except that 
one microphone may serve more than one exit provided the proximity of 
the exits allows unassisted verbal communication between seated flight 
attendants.
    (g) There must be a means for manual activation of an aural 
emergency alarm system, audible during normal and emergency conditions, 
to enable crewmembers on the flight deck and at each pair of required 
floor level emergency exits to alert occupants of the crew rest 
compartment of an emergency situation. Use of a public address or crew 
interphone system will be acceptable, provided an adequate means of 
differentiating between normal and emergency communications is 
incorporated. The system must be powered in flight, after the shutdown 
or failure of all engines and auxiliary power units (APU), or the 
disconnection or failure of all power sources dependent on their 
continued operation (i.e., engine & APU), for a period of at least ten 
minutes.
    (h) There must be a means, readily detectable by seated or standing 
occupants of the crew rest compartment, which indicates when seat belts 
should be fastened. In the event there are no seats, at least one means 
must be provided to cover anticipated turbulence (e.g., sufficient 
handholds). Seat belt type restraints must be provided for berths and 
must be compatible for the sleeping attitude during cruise conditions. 
There must be a placard on each berth requiring that seat belts must be 
fastened when occupied. If compliance with any of the other 
requirements of these special conditions is predicated on specific head 
location, there must be a placard identifying the head position.
    (i) In lieu of the requirements specified in Sec.  25.1439(a) at 
Amendment 25-38 that pertain to isolated compartments and to provide a 
level of safety equivalent to that which is provided occupants of a 
small, isolated galley, the following equipment must be provided in the 
crew rest compartment:
    (1) At least one approved hand-held fire extinguisher appropriate 
for the kinds of fires likely to occur.
    (2) Two protective breathing equipment (PBE) devices approved to 
Technical Standard Order (TSO)-C116 or equivalent, suitable for 
firefighting, or one PBE for each hand-held fire extinguisher, 
whichever is greater.
    (3) One flashlight.

    Note: Additional PBEs and fire extinguishers in specific 
locations, (beyond the minimum numbers prescribed in special 
condition (i)) may be required as a result of any egress analysis 
accomplished to satisfy special condition (b)(1).

    (j) A smoke or fire detection system (or systems) must be provided 
that monitors each occupiable area within the crew rest compartment, 
including those areas partitioned by curtains. Flight tests must be 
conducted to show compliance with this requirement. Each system (or 
systems) must provide:
    (1) A visual indication to the flight deck within one minute after 
the start of a fire;
    (2) An aural warning in the crew rest compartment; and
    (3) A warning in the main passenger cabin. This warning must be 
readily detectable by a flight attendant, taking into consideration the 
positioning of flight attendants throughout the main passenger 
compartment during various phases of flight.
    (k) The crew rest compartment must be designed such that fires 
within the compartment can be controlled without a crewmember having to 
enter the compartment, or the design of the access

[[Page 86277]]

provisions must allow crewmembers equipped for firefighting to have 
unrestricted access to the compartment. The time for a crewmember on 
the main deck to react to the fire alarm, to don the firefighting 
equipment, and to gain access must not exceed the time for the 
compartment to become smoke-filled, making it difficult to locate the 
fire source.
    (l) There must be a means provided to exclude hazardous quantities 
of smoke or extinguishing agent originating in the crew rest 
compartment from entering any other compartment occupied by crewmembers 
or passengers. This means must include the time periods during the 
evacuation of the crew rest compartment and, if applicable, when 
accessing the crew rest compartment to manually fight a fire. Smoke 
entering any other compartment occupied by crewmembers or passengers 
when the access to the crew rest compartment is opened, during an 
emergency evacuation, must dissipate within five minutes after the 
access to the crew rest compartment is closed.
    (1) Hazardous quantities of smoke may not enter any other 
compartment occupied by crewmembers or passengers during subsequent 
access to manually fight a fire in the crew rest compartment (the 
amount of smoke entrained by a firefighter exiting the crew rest 
compartment through the access is not considered hazardous).
    (2) There must be a provision in the firefighting procedures to 
ensure that all door(s) and hatch(es) at the crew rest compartment 
outlets are closed after evacuation of the crew rest compartment and, 
during firefighting to minimize smoke and extinguishing agent from 
entering other occupiable compartments.
    (3) During the 1-minute smoke detection time, penetration of a 
small quantity of smoke from the crew rest compartment into an occupied 
area is acceptable. Flight tests must be conducted to show compliance 
with this requirement.
    (4) If a built-in fire extinguishing system is used in lieu of 
manual firefighting, then the fire extinguishing system must be 
designed so that no hazardous quantities of extinguishing agent will 
enter other compartments occupied by passengers or crew. The system 
must have adequate capacity to suppress any fire occurring in the crew 
rest compartment, considering the fire threat, volume of the 
compartment and the ventilation rate.
    (m) There must be a supplemental oxygen system equivalent to that 
provided for main deck passengers for each seat and berth in the crew 
rest compartment. The system must provide an aural and visual warning 
to warn the occupants of the crew rest compartment to don oxygen masks 
in the event of decompression. The warning must activate before the 
cabin pressure altitude exceeds 15,000 feet. The aural warning must 
sound continuously for a minimum of five minutes or until a reset push 
button in the crew rest compartment is depressed. Procedures for crew 
rest occupants in the event of decompression must be established. These 
procedures must be transmitted to the operator for incorporation into 
their training programs and appropriate operational manuals.
    (n) The following requirements apply to crew rest compartments that 
are divided into several sections by the installation of curtains or 
partitions:
    (1) To compensate for sleeping occupants, there must be an aural 
alert that can be heard in each section of the crew rest area 
compartment that accompanies automatic presentation of supplemental 
oxygen masks. A visual indicator that occupants must don an oxygen mask 
is required in each section where seats or berths are not installed. A 
minimum of two supplemental oxygen masks is required for each seat or 
berth. There must also be a means by which the oxygen masks can be 
manually deployed from the flight deck.
    (2) A placard is required adjacent to each curtain that visually 
divides or separates, for privacy purposes, the crew rest area 
compartment into small sections. The placard must require that the 
curtain(s) remains open when the private section it creates is 
unoccupied.
    (3) For each crew rest section created by the installation of a 
curtain, the following requirements of these special conditions must be 
met with the curtain open or closed:
    (i) Emergency illumination (Special condition (e)).
    (ii) Emergency alarm system (Special condition (g)).
    (iii) Seat belt fasten signal or return to seat signal as 
applicable (Special condition (h)).
    (iv) The smoke or fire detection system (Special condition (j)).
    (4) Crew rest compartments visually divided to the extent that 
evacuation could be affected must have exit signs that direct occupants 
to the primary stairway exit. The exit signs must be provided in each 
separate section of the crew rest compartment and must meet the 
requirements of Sec.  25.812(b)(1)(i) at Amendment 25-58. An exit sign 
with reduced background area as described in special condition (d)(1) 
may be used to meet this requirement.
    (5) For sections within a crew rest compartment that are created by 
the installation of a partition with a door separating the sections, 
the following requirements of these special conditions must be met with 
the door open or closed:
    (i) There must be a secondary evacuation route from each section to 
the main deck, or alternatively, it must be shown that any door between 
the sections has been designed to preclude anyone from being trapped 
inside the compartment. Removal of an incapacitated occupant within 
this area must be considered. A secondary evacuation route from a small 
room designed for only one occupant for short time duration, such as a 
changing area or lavatory, is not required. However, removal of an 
incapacitated occupant within this area must be considered.
    (ii) Any door between the sections must be shown to be openable 
when crowded against, even when crowding occurs at each side of the 
door.
    (iii) There may be no more than one door between any seat or berth 
and the primary stairway exit.
    (iv) There must be exit signs in each section meeting the 
requirements of Sec.  25.812(b)(1)(i) at Amendment 25-58 that direct 
occupants to the primary stairway exit. An exit sign with reduced 
background area as described in special condition (d).(1) may be used 
to meet this requirement.
    (v) Special conditions (e) (emergency illumination), (g) (emergency 
alarm system), (h) (fasten seat belt signal or return to seat signal as 
applicable), and (j) (smoke or fire detection system) must be met with 
the door open or closed.
    (vi) Special conditions (f) (two-way voice communication) and (i) 
(emergency firefighting and protective equipment) must be met 
independently for each separate section except for lavatories or other 
small areas that are not intended to be occupied for extended periods 
of time.
    (o) Where a waste disposal receptacle is fitted, it must be 
equipped with a built-in fire extinguisher designed to discharge 
automatically upon occurrence of a fire in the receptacle.
    (p) Materials (including finishes or decorative surfaces applied to 
the materials) must comply with the flammability requirements of Sec.  
25.853 at Amendment 25-66. Mattresses must comply with the flammability 
requirements of Sec.  25.853(b) and (c) at Amendment 25-66.
    (q) If a lavatory is installed, all lavatories within the crew rest 
are required to meet the same requirements as those for a lavatory 
installed on the

[[Page 86278]]

main deck except with regard to special condition (j) for smoke 
detection.
    (r) When a crew rest compartment is installed or enclosed as a 
removable module in part of a cargo compartment or is located directly 
adjacent to a cargo compartment without an intervening cargo 
compartment wall, the following applies:
    (1) Any wall of the module (container) forming part of the boundary 
of the reduced cargo compartment, subject to direct flame impingement 
from a fire in the cargo compartment and including any interface item 
between the module (container), and the airplane structure or systems, 
must meet the applicable requirements of Sec.  25.855 at Amendment 25-
60.
    (2) Means must be provided so that the fire protection level of the 
cargo compartment meets the applicable requirements of Sec. Sec.  
25.855 at amendment 25-60, 25.857 at amendment 25-60 and 25.858 at 
amendment 25-54 when the module (container) is not installed.
    (3) Use of each emergency evacuation route must not require 
occupants of the crew rest compartment to enter the cargo compartment 
in order to return to the passenger compartment.
    (4) The aural warning in special condition (g) must sound in the 
crew rest compartment in the event of a fire in the cargo compartment.
    (s) Means must be provided to prevent access into the Class C cargo 
compartment during all airplane operations and to ensure that the 
maintenance door is closed during all airplane flight operations.
    (t) All enclosed stowage compartments within the crew rest that are 
not limited to stowage of emergency equipment or airplane-supplied 
equipment (e.g., bedding) must meet the design criteria given in the 
table below. As indicated by the table below, this special condition 
does not address enclosed stowage compartments greater than 200 ft\3\ 
in interior volume. The in-flight accessibility of very large, enclosed 
stowage compartments and the subsequent impact on the crewmember's 
ability to effectively reach any part of the compartment with the 
contents of a hand fire extinguisher will require additional fire 
protection considerations similar to those required for inaccessible 
compartments such as Class C cargo compartments.

                                                          Stowage Compartment Interior Volumes
--------------------------------------------------------------------------------------------------------------------------------------------------------
       Fire protection features                  Less than 25 ft\3\                   25 ft\3\ to 57 ft\3\                  57 ft\3\ to 200 ft\3\
--------------------------------------------------------------------------------------------------------------------------------------------------------
Materials of Construction \1\........  Yes..................................  Yes.................................  Yes.
Detectors \2\........................  No...................................  Yes.................................  Yes.
Liner \3\............................  No...................................  No..................................  Yes.
Locating Device \4\..................  No...................................  Yes.................................  Yes.
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ Materials of Construction: The material used to construct each enclosed stowage compartment must at least be fire resistant and must meet the
  flammability standards established for interior components per the requirements of Sec.   25.853. For compartments less than 25 ft\3\ in interior
  volume, the design must ensure the ability to contain a fire likely to occur within the compartment under normal use.
\2\ Detectors: Enclosed stowage compartments equal to or exceeding 25 ft\3\ in interior volume must be provided with a smoke or fire detection system to
  ensure that a fire can be detected within a one-minute detection time. Flight tests must be conducted to show compliance with this requirement. Each
  system (or systems) must provide:
(a) A visual indication in the flight deck within one minute after the start of a fire;
(b) An aural warning in the crew rest compartment; and
(c) A warning in the main passenger cabin. This warning must be readily detectable by a flight attendant, taking into consideration the positioning of
  flight attendants throughout the main passenger compartment during various phases of flight.
\3\ Liner: If it can be shown that the material used to construct the stowage compartment meets the flammability requirements of a liner for a Class B
  cargo compartment, then no liner would be required for enclosed stowage compartments equal to or greater than 25 ft\3\ in interior volume but less
  than 57 ft\3\ in interior volume. For all enclosed stowage compartments equal to or greater than 57 ft\3\ in interior volume but less than or equal to
  200 ft\3\, a liner must be provided that meets the requirements of Sec.   25.855 at Amendment 25-60 for a class B cargo compartment.
\4\ Location Detector: Crew rest areas which contain enclosed stowage compartments exceeding 25 ft\3\ interior volume and which are located away from
  one central location such as the entry to the crew rest area or a common area within the crew rest area would require additional fire protection
  features and/or devices to assist the firefighter in determining the location of a fire.

    Issued in in Kansas City, Missouri, on December 8, 2023.
Patrick R. Mullen,
Manager, Technical Policy Branch, Policy and Standards Division, 
Aircraft Certification Service.
[FR Doc. 2023-27396 Filed 12-12-23; 8:45 am]
BILLING CODE 4910-13-P