[Federal Register Volume 59, Number 94 (Tuesday, May 17, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-11847]
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[Federal Register: May 17, 1994]
_______________________________________________________________________
Part VI
Department of Transportation
_______________________________________________________________________
Federal Aviation Administration
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14 CFR Part 23
Airworthiness Standards; Emergency Exit Provisions for Normal, Utility,
Acrobatic, and Commuter Category Airplanes; Final Rule
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 23
[Docket No. 26324; Amendment No. 23-46]
RIN 2120-AD33
Airworthiness Standards; Emergency Exit Provisions for Normal,
Utility, Acrobatic, and Commuter Category Airplanes
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final rule.
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SUMMARY: This final rule amends the emergency egress airworthiness
standards for normal, utility, acrobatic, and commuter category
airplanes. This amendment adds requirements for ditching and flightcrew
emergency exits for these airplane categories, and provides alternative
emergency exit requirements for commuter category airplanes that are
consistent with the requirements for similarly sized small transport
airplanes. This amendment is intended to ensure that emergency exits
are available to all flightcrew members, that exits are available to
all multiengine airplane occupants for emergency egress during an
emergency landing in water, and to provide alternative exit
requirements for commuter category airplanes consistent with the
existing transport category airworthiness standards.
EFFECTIVE DATE: June 16, 1994.
FOR FURTHER INFORMATION CONTACT:
Mike Downs, Aerospace Engineer, Standards Office (ACE-110), Small
Airplane Directorate, Federal Aviation Administration, room 1544, 601
East 12th Street, Kansas City, Missouri 64106, telephone (816) 426-
5688.
SUPPLEMENTARY INFORMATION:
Background
This amendment is based on Notice of Proposed Rulemaking (NPRM) No.
90-20 (55 FR 35544, August 30, 1990). All comments received in response
to Notice No. 90-20 have been considered in adopting this amendment.
Notice 78-14, published on October 10, 1978 (43 FR 46734), proposed
interim airworthiness requirements for increased takeoff gross weight
and passenger seating capacity of certain existing small, propeller-
driven, multiengine airplanes. That rulemaking action resulted from a
petition for rulemaking to allow certain small airplanes to be type
certificated to maximum takeoff weights greater than 12,500 pounds
without complying with the transport category type certification
requirements of part 25. Special Federal Aviation Regulations (SFAR) 41
(44 FR 53723, September 17, 1979), which became effective October 17,
1979, resulted from Notice 78-14.
In the early 1980's, the FAA explored the feasibility of a new part
24 that would provide airworthiness standards for a new light transport
category airplane. The proposal was withdrawn because it was not cost
effective. SFAR 41 provides alternative type design standards for an
airplane of the same gross weight that would be required to comply with
part 25 airworthiness standards. Section 5 of SFAR 41 provides specific
requirements for passenger entry doors and additional emergency exits.
That section requires, in part, that the passenger entry door qualify
as a floor-level emergency exit. For airplanes with a total seating
capacity of 15 or fewer, that section requires, in addition to the
passenger entry door, an emergency exit as defined in Sec. 23.807(b),
on each side of the cabin. For airplanes with a total passenger seating
capacity of 16 through 23, that section required three emergency exits
as defined in Sec. 23.807(b), with one on the same side as the door and
two on the side opposite the door.
SFAR 41 was amended (45 FR 25047, April 14, 1980) for clarification
and editorial corrections. SFAR 41B (45 FR 80973, December 8, 1980)
further amended the regulation to specify additional requirements for
optional compliance with the International Civil Aviation Organization
(ICAO), Annex 8, Part III, Airworthiness Standards, which apply to
airplanes weighing 5,700 kg (12,566 pounds) or more.
After the expiration of SFAR 41B on October 17, 1981, and
termination of the Light Transport Airplane Airworthiness Review, the
FAA issued SFAR 41C (47 FR 35153, August 12, 1982), effective September
13, 1982. The amended SFAR: (1) Eliminated the 12,500-pound maximum
zero fuel weight restriction; (2) limited the number of passenger seats
to 19 for those small propeller-driven, multiengine airplanes that
operate at a certificated gross takeoff weight in excess of 12,500
pounds; and (3) relaxed the landing distance determination requirement,
making it consistent with the similar requirements in part 23 and part
25. The wording of section 5 was amended, in part, to require that
airplanes with a total passenger seating capacity of 16 through 19 be
designed with three emergency exits, as defined in Sec. 23.807(b), with
one on the same side as the door and two on the side opposite the door.
On November 15, 1983, Notice 83-17 (48 FR 52010) proposed to amend
parts 21, 23, 36, 91 and 135 of the Federal Aviation Regulations (FAR)
to adopt certification procedures, airworthiness and noise standards,
and operating rules for a new commuter category for airplanes type
certificated to the FAR. That notice, in part, proposed to amend
Sec. 23.807 to require the same number of emergency exits in commuter
category airplanes as the number required for airplanes meeting the
SFAR 41C requirements.
On December 12, 1986, Notice 86-19 (51 FR 44878), titled ``Small
Airplane Airworthiness Review Program Notice No. 1,'' was published
proposing new requirements that would enhance cabin safety in normal,
utility, and acrobatic category airplanes. Since final rules for
commuter category airplanes had not been adopted at the time Notice 86-
19 was published, that notice did not address commuter category
airplanes. In Notice 86-19, the FAA referred to the proposed commuter
category airplane rule and noted that additional rulemaking action
would be initiated to enhance the cabin safety of commuter category
airplanes if the proposals in Notice 83-17 were adopted.
As a result of Notice 83-17, amendment 23-34 (52 FR 1806, January
15, 1987) was adopted specifying minimum airworthiness standards for a
new commuter category airplane. That final rule, in part, amended
Sec. 23.807 by adding a new paragraph (d) that required commuter
category airplanes with a seating capacity of 15 or fewer to have an
emergency exit on each side of the cabin in addition to the entry door;
and commuter category airplanes with a total seating capacity of 16
through 19 to have three emergency exits, with one on the same side as
the passenger entry door and two on the opposite side. Those
requirements were substantively identical to the requirements in SFAR
41C.
As a result of Notice 86-19, amendment 23-36 (53 FR 30802, August
15, 1988) was adopted to provide upgraded airworthiness standards for
cabin safety and occupant protection for part 23 airplanes.
Since final action to incorporate commuter category airplane
airworthiness standards into the FAR had not been completed at the time
Notice 86-19 was published, requirements for commuter category
airplanes were not specifically addressed in the proposals of that
notice. The proposals in Notice 86-19 were formulated to be compatible
with the commuter category airplane cabin safety airworthiness
standards that were adopted in amendment 23-34, with the exception of
the requirements for dynamic testing of seats and the requirements for
shoulder harnesses at the passenger seats. The cabin safety standards
adopted by amendment 23-36 were formulated considering both the public
comments to Notice 86-19 and the changes to part 23 adopted by
amendment 23-34. The requirements for the number of emergency exits in
commuter category airplanes, as adopted by amendment 23-34, were not
changed by amendment 23-36. The commuter category final rule moved the
requirements in Sec. 23.807(d)(3) to a new Sec. 23.811(b), and the
requirements of Sec. 23.807(d)(4) were moved to a new Sec. 23.813.
The intent of section 5 of SFAR 41 was to require an additional
emergency exit (above the requirements for normal category airplanes)
for airplanes with a total seating capacity, including pilot seats, of
12 to 15; therefore, when an airplane with a seating capacity of 11 or
fewer, including pilot seats, was certificated to the airworthiness
standards of SFAR 41, the emergency exit requirements in Sec. 23.807
for normal category airplanes were applicable. Since the amendment of
the emergency exit standards of Sec. 23.807(d)(1)(i), the FAA has
reconsidered the number of exits required to commuter category
airplanes with a cabin seating capacity of fewer than 9 passengers.
Section 23.807(d)(1) is applicable to every commuter category airplane,
including those airplanes with a total passenger seating capacity of 9
or fewer. This section increases the level of cabin safety requirements
for commuter category airplanes.
Since incorporation of amendment 23-34 into part 23, airplane
manufacturers and modifiers have petitioned the FAA for exemption from
Sec. 23.807(d)(1)(i) or Sec. 23.807(d)(1)(ii). Those standards require
that: Commuter category airplanes with a total passenger seating
capacity of 15 or fewer have an emergency exit on each side of the
cabin in addition to the passenger entry door; and commuter category
airplanes with a total passenger seating capacity of 16 through 19 have
three emergency exits in addition to the passenger entry door, with one
emergency exit on the same side as the door and two exits on the
opposite side. Frequently, those petitions have noted the differences
in the requirements of Sec. 23.807(d)(1) and the emergency exit
requirements for similarly sized transport category airplanes. Section
25.807(c)(1) requires, in part, that transport category airplanes with
a passenger seating capacity of 19 passengers or fewer provide at least
one emergency exit on each side of the fuselage and that the main entry
door may be considered one of the emergency exits when it meets the
requirements of Secs. 25.807(c)(1) and 25.783.
The petitioners, in general, have proposed to provide the number of
emergency exits required by Sec. 25.807(c)(1) for transport category
airplanes instead of complying with the requirements of
Sec. 23.807(d)(1). In support of these petitions, the petitioners point
out that their commuter category airplanes have compensating features
that include a variety of other cabin safety provisions and meet the
higher levels of safety afforded by small transport category airplanes.
Other cabin safety provisions include larger exits, wider aisles,
emergency lighting and additional exit marking features, all of which
exceed the current requirements for commuter category airplanes. In
granting these petitions the FAA stated that the number of emergency
exits is only one aspect of overall cabin safety that is provided by
the airplane design. For this reason, the FAA initiated a project to
amend part 23 to provide that, as an alternative to compliance with the
requirements of Sec. 23.807(d)(1), commuter category airplanes may be
designed with the number of emergency exists required for transport
category airplanes in Sec. 25.807(c)(1).
The FAA conducted a review of the cabin safety standards required
for commuter category airplanes in part 23 and the cabin safety
provisions required for small transport category airplanes in part 25.
The review showed that part 25 standards require numerous features,
including a specified emergency exit configuration, emergency lighting,
minimum aisle width, and additional exit markings that aid the
occupants of transport category airplanes in locating, reaching, and
passing through the emergency exits. These additional airworthiness
requirements are important factors in minimizing the time required for
occupants to safely exit the airplane through a limited number of
exits. As an alternative, this final rule allows commuter category
airplanes to comply with emergency exit requirements and other cabin
safety standards that are substantively the same as those for similarly
sized transport category airplanes.
This final rule amends the emergency exit requirements to provide
the following: (1) Additional emergency landing requirements that give
the airplane occupants every reasonable chance of escaping serious
injury in a survivable crash landing; (2) emergency exit size and step
up/step down limitations that enable the airplane occupants to readily
pass through the exits; (3) emergency exit marking requirements that
ensure the exits can be identified easily in an emergency; (4)
emergency lighting requirements that ensure adequate lighting for rapid
egress from the airplane; and (5) wider aisles and additional emergency
exit access requirements that ensure the airplane occupants have a path
to the available emergency exits.
This final rule also adopts new requirements for emergency exit
ditching provisions for multiengine airplanes that are type
certificated to the airworthiness standards of part 23. The FAA
anticipates an increase in the use of multiengine normal and commuter
category airplanes in overwater operation. Airports located near large
bodies of water have increased the number of departures and approaches
that are conducted over water. Since ditching provisions are critical
for occupant egress following an emergency landing in water, this
proposal would require that the airplane design provide the airplane
occupants with a means of exiting the airplane following an emergency
landing in water.
Further, this final rule adopts a new airworthiness standard to
require that, in emergency landings, emergency exits are readily
available to crewmembers when the airplane is configured in a manner
that makes the passenger emergency exits inaccessible to the crew. The
FAA has previously required additional emergency exits for normal
category or commuter category sized airplane designs, where the cabin
interiors were configured with cargo nets or other barriers that
blocked crewmember access to the passenger emergency exits. Although
Sec. 135.87(c)(7) requires at least one emergency or regular exit to be
available for crew egress in certain airplanes used in cargo-only
operations, there is no such requirement in part 23. This newly adopted
requirement is also similar to the standard that is used for transport
category airplanes.
Discussion of Comments
General
Interested persons were invited to participate in the development
of these final rules by submitting written data, views, or arguments to
the regulatory docket on or before February 26, 1991. Five commenters
responded to Notice No. 90-20. Minor technical and editorial changes
have been made to the proposed rules based on relevant comments
received and after further review by the FAA.
One commenter expresses support for the entire proposal without
making any specific comments. Another commenter provides comments only
to specific proposals. One commenter feels that the commuter category
requirements of part 23 already provide an adequate level of safety and
asks for an explanation of why the FAA is using part 25 requirements in
part 23. This requested explanation can be found in the background
section above.
One commenter expresses general agreement with the objectives of
the rulemaking and discusses the factors that the commenter considers
important to the rapid evacuation of an airplane. This commenter lists
those factors as exit availability, adequate exit size, reasonable step
up and step down criteria at emergency exits, and illumination of the
area immediately outside the exit. The FAA agrees that these factors
are also important but questions the relative significance the
commenter ascribes to them. The commenter did not submit any supporting
data for the comment.
One commenter supports the addition of the small transport category
airplane safety features of part 25 to part 23 commuter category
airplanes, but strongly opposes tying these features to a reduction in
the number of emergency exits. This rulemaking action provides
alternative emergency exit requirements for part 23 commuter category
airplanes that are consistent with those requirements for similarly
sized part 25 small transport category airplanes. This amendment will
give the applicant the option of either meeting existing
Sec. 23.807(d)(1) emergency exit requirements, or reducing the number
of emergency exits to that required by Sec. 23.807(d)(4) and meeting
additional cabin safety requirements specified in Sec. 23.807(d)(4).
These requirements are similar to those standards required for part 25
small transport airplanes.
Discussion of Comments to Specific Sections of Part 23
Proposal 1. This proposal contains the authority citation for part
23.
Proposal 2. This proposal would add a downward inertia load
requirement to the emergency landing ultimate static load factors when
an applicant for type certification chooses to comply with the
alternate emergency exit requirements of Sec. 23.807(d)(4). This is
intended to ensure a specific minimum download airframe strength to
protect occupants from structural failures that could prevent their
exiting the airplane through the emergency exits or the passenger entry
door after an emergency landing.
One commenter believes the 6g downward force is excessive for part
23 airplanes. The FAA disagrees. In the 1970's, the FAA and the
National Aeronautics and Space Administration (NASA) conducted
considerable research concerning the crash dynamic characteristics of
small general aviation airplanes. NASA conducted a test series of 21
controlled full-scale impact tests on single-engine and twin-engine
general aviation airplanes. Results from those tests provided a
substantial qualitative and quantitative data base regarding the crash
behavior and occupant impact protection characteristics of small
general aviation airplanes. The results of the research and tests
revealed that the downward force occurring during the full-scale impact
tests were in excess of 6g in most cases; therefore, the 6g downward
inertia load factor was proposed to ensure a minimum download
requirement.
One commenter recommends higher downward inertia loads and a
correspondingly higher descent velocity, which was proposed as an
alternate approach to establishing the static downward load factor. The
FAA disagrees. Although downward load factors may be greater than 6g
during emergency landing conditions, the FAA intends to make the
airworthiness standards for commuter category airplanes consistent with
those for small transport airplanes; therefore, the 6g downward load
factor will remain as a minimum requirement. Accordingly, that portion
of Sec. 23.561(b)(2)(iv) that specifies the use of any lesser force is
deleted in the final rule. The removal of this lesser force from the
proposed rule further standardizes the alternate cabin safety and
emergency exit requirements of part 23 commuter category airplanes with
that of part 25 small transport airplanes. The alternative downward
force was similarly deleted from part 25. This proposal is adopted with
the aforementioned change.
Proposal 3. This proposal would move certain requirements for
commuter category airplane passenger entry doors and associated
integral stairs from Sec. 23.807(d)(1) to a new Sec. 23.783(f), and add
size and shape requirements for the passenger entry door. The final
rule clarifies those standards that apply to the passenger entry doors
of any commuter category airplane, regardless of the number of
emergency exits. One comment was received and it supports the FAA's
proposal. Accordingly, this proposal is adopted as proposed.
Proposal 4. Proposed new Sec. 23.812 would require that an
emergency lighting system be installed when the applicant for type
certification chooses to comply with the alternate emergency exit
provisions of proposed Sec. 23.807(d)(4). Proposed Sec. 23.803(b)
requires the use of that emergency lighting system during the emergency
evacuation demonstration required for commuter category airplanes.
Two comments were received on this proposal. Both commenters
suggest that proposed Sec. 23.803(b) be rewritten to eliminate the
evacuation demonstration when they comply with Sec. 23.807(d)(4). Both
commenters argue that, in their experience, part 25 emergency exit
requirements ensure rapid evacuation as long as the airplane is
relatively small.
The FAA disagrees. Emergency evacuation demonstrations for
passenger-carrying airplanes are consistent with aviation safety. In
the absence of showing an ability to evacuate airplanes and the
correction of faults in designs and procedures as they are revealed by
tests, these demonstrations will result in lives saved. Furthermore, it
is not justifiable to exempt an applicant from Sec. 23.803 because the
applicant chooses to comply with Sec. 23.807(d)(4), since the applicant
that complies with Sec. 23.807(d)(4) has one less emergency exit than
the applicant that complies with Sec. 23.807(d)(1). This proposal is
adopted as proposed.
Proposal 5. This proposal would add requirements for emergency
exits that are available to the flightcrew in an emergency landing.
These requirements are intended to ensure that the crew has ready
access to an emergency exit when their access to the cabin area aft of
the cockpit is blocked by cargo constraints or other barriers. Both
normal category (single & multiengine) and commuter category airplanes
have been modified for hauling freight, and have included cargo
restraint barriers that blocked crew access to the emergency exit in
the passenger compartment. Accordingly, these standards were proposed
to apply to all categories of airplanes certificated to the
airworthiness standards of part 23. These requirements are similar to
existing requirements in Sec. 25.807(f) for transport category
airplanes.
One commenter suggests that the FAA provide guidance through an
advisory circular or other means on how to determine when the cabin
entry door or other passenger emergency exit does not offer a
convenient and readily accessible means of evacuation for the
flightcrew. The FAA agrees that further guidance may be required;
however, the FAA will review the need for further guidance after the
adoption of the final rule.
One commenter supports the proposal to establish a standard minimum
for flightcrew emergency exits; however, the commenter believes that
the FAA should conduct tests to determine the minimum exit size that
would accommodate pilots in both the ninety-fifth and fifth size
percentiles.
Tests to determine exit size were conducted prior to the adoption
of a Civil Air Regulations (CAR) amendment in 1962; however, the
biometric data derived was taken from the general population and not
from a population comprised of pilots. The results of the tests were
instrumental in the determination of emergency exit and aisle width
requirements. The size of the exits has been determined previously and
no change was proposed in the notice. This proposal is adopted without
change.
Proposal 6. This proposal would allow type certification of
commuter category airplanes configured with one emergency exit on the
side of the cabin opposite the passenger entry door when additional
cabin safety features are provided in the airplane design. This
proposal states the additional cabin safety features required to comply
with the alternative emergency exit provisions. This proposal would
move specific requirements for the passenger entry door and associated
integral stairs from Sec. 23.807(d)(1) to proposed Sec. 23.785(f). This
proposal would move from Sec. 23.807(d)(1) to Sec. 23.807(d)(3) the
requirement that each emergency exit that is not a floor-level exit be
located over a wing or, if the exit is not less than six feet from the
ground, have a means to assist occupants in reaching the ground.
Because there are many airports where takeoffs and landings are
conducted over large bodies of water, this proposal includes
airworthiness standards for multiengine airplanes that require
emergency exits for ditching to be located above the waterline. This
proposal would require that the airplane design provide the airplane
occupants with a means of exiting the airplane following an emergency
landing in water.
Nine comments were received regarding proposed Secs. 23.807(d) and
23.807(e). Two commenters state that, according to the preamble to the
NPRM, Sec. 23.807(d)(1)(i) is intended to apply to all commuter
category airplanes. The commenters further state that this appears
inconsistent and impractical when considering a two-place cargo
airplane with a cargo barrier immediately aft of the entrance door. The
commenters propose to solve this problem by making proposed
Sec. 23.807(d)(4)(i) applicable to all commuter category airplanes.
The FAA disagrees. Proposed Sec. 23.807(d)(1) is intended to apply
to all commuter category airplanes, but Sec. 23.807(d)(1)(i) is
intended to apply only to commuter category airplanes with a total
seating capacity of 15 or fewer. Furthermore, the problem of compliance
for two-place cargo airplanes is not considered to be a certification
problem because there is no special certification for cargo airplanes.
The purpose of this rule is to provide alternative emergency exit and
cabin safety requirements for commuter category airplanes that are
consistent with the airworthiness standards used by small transport
airplanes in part 25. This will enable the applicant to choose the
requirements of Sec. 23.807(d)(4) instead of Sec. 23.807(d)(1).
Two commenters propose to delete the reference to Sec. 23.803(b) in
proposed Sec. 23.807(d)(4)(iii), stating that it is unnecessary. The
FAA disagrees. The reference to Sec. 23.803(b) is a necessary part of
Sec. 23.807(d)(4)(iii), directing the applicant to the remaining safety
requirements of Sec. 23.807(d)(4) that must be met.
One commenter states that multiengine airplanes are required to
have emergency exits in accordance with Sec. 23.807(a) and that
proposed Sec. 23.807(e) would effectively require two additional exits,
even if the Sec. 23.807(a) exit, the main door, or both are above the
waterline. The FAA agrees. The intent of the rule is to require that
all multiengine airplanes have available exits for emergency egress
following an emergency landing in water; therefore, the reference made
in the NPRM under Sec. 23.807(e) to Sec. 23.807(b) or (d) is changed to
Sec. 23.807(a) or (d). Section 23.807(e)(1) remains unchanged.
One commenter supports the optional exit configuration introduced
by Sec. 23.807(d)(4) and states that it is in substantive alignment
with part 25.
One commenter opposes the proposal to allow the manufacturer to
reduce the number of exits available in exchange for including
additional emergency evacuation design features. The commenter further
states that emergency evacuation is most critically affected by the
proximity of exits to evacuees, and that by reducing the number of
exits, evacuation time will increase. The commenter then proposes to
extend the useful time for evacuation by requiring the additional part
25 requirement of low flammability interior materials.
The FAA agrees that the number and proximity of exits in an
airplane are two parameters that influence evacuation time. One of the
purposes of this rulemaking action is to provide an alternative
emergency exit configuration for commuter category airplanes without
decreasing cabin safety. Since the service history of small transport
category airplanes with regard to emergency exit standards has proven
successful, this rule provides the applicant with the option of
reducing the number of emergency exits required. The compensation for
this reduction is accomplished by meeting additional cabin safety
requirements. The overall effect is an equivalent level of safety
between Sec. 23.807(d)(1) and Sec. 23.807(d)(4), and the
standardization of alternative cabin safety and emergency exit
requirements for small transport airplanes and commuter category
airplanes that comply with Sec. 23.807(d)(4). The request for
additional airworthiness standards for low flammability interior
materials is beyond the scope of this rulemaking.
One commenter recommends increasing the minimum size of the exit in
Secs. 23.807(d)(4)(i) and (ii), to the size of a type I exit and
requiring it to be floor level. The commenter states that this is
necessary because it is the only exit besides the main entry door, and
it replaces two other type III exits. The commenter further contends
that the flow rates for the type III exits, as listed in Sec. 25.807,
support the commenter's opinion that the type III exits are slow and
cumbersome to use; and with such obstacles as allowed in proposed
Sec. 23.807(d)(3), their efficiency will be reduced even more.
The FAA disagrees. A requirement for exits larger than those
proposed is outside the scope of the rulemaking for the reasons noted
above. Furthermore, by meeting the requirements of the proposed exit
size and the other cabin safety requirements of Sec. 23.807(d)(4)(iii),
minimum requirements for this alternative to Sec. 23.807(d)(4) have
been established. This proposal is adopted with the aforementioned
changes.
Proposal 7. This proposal would add emergency exit marking
requirements applicable when an applicant for type certification
chooses to comply with the alternate emergency exit provisions of
proposed Sec. 23.807(d)(4). These proposed requirements would result in
emergency exits that are easier to locate in adverse conditions and
easier to open once located. The proposal includes additional
requirements for both internal and external marking of the emergency
exits.
One commenter suggests that, even though some additions to the
current Sec. 23.811 may be necessary, a full part 25 treatment is not
necessarily appropriate for small part 23 commuter airplanes. The
commenter recommends that the FAA reconsider this proposal and suggests
that a human factor analysis study, determining how people react in
commuter size cabins, be completed before any rulemaking activity
begins.
The FAA disagrees. Section 23.811(c) provides additional
airworthiness requirements for emergency exit markings that would be
applicable when certification to the emergency exit provisions of
Sec. 23.807(d)(4) is requested. The choice is that of the applicant.
Also, the service experience gained by part 25 small transport
airplanes, and the experience gained from part 23 commuter category
applicants that have been granted exemptions from the emergency exit
requirements of Sec. 23.807(d)(1), has proven successful. Accordingly,
this alternative is considered suitable for all applicants and further
human factor analysis studies are not required.
One commenter states that proposed Sec. 23.811(c) would require
exit path markings that would be unnecessary and burdensome and
suggests that it would provide no added safety benefit. The FAA
disagrees. This section requires a means to assist occupants in
locating emergency exists in dense smoke and does not limit these means
to floor proximity lighting only. This proposal is adopted as proposed
with the exception of minor editorial corrections.
Proposal 8. This proposal would add requirements for an emergency
lighting system that would apply to an applicant for type certification
that chooses to comply with the alternative emergency exit provisions
of proposed Sec. 23.807(d)(4). The proposal defines specific minimum
requirements for supplying power, arming, and activating the emergency
lighting system. The impact activation requirement is consistent with
that for emergency locator transmitters. The proposal would also set
certain requirements for illumination, function, and the survivability
standards of the emergency lighting system. An emergency lighting
system that complies with these proposed requirements would aid
occupants in locating the emergency exits and exiting after an
emergency landing.
One commenter states that more and brighter lights may be
detrimental to a fast egress when all human factors are considered. The
commenter recommends additional research before any rulemaking activity
begins.
The FAA disagrees. The requirements for part 25 airplanes have been
found to be suitable for part 23 and an alternative to the current part
23 standard. Furthermore, these improvements in lighting have already
been tested by applicants that have been granted exemptions from
Sec. 23.807.
One commenter does not understand why the requirement to provide
emergency lighting should be limited to applicants that have chosen to
comply with Sec. 23.807(d)(4) requirements. The commenter further
suggests that emergency lighting requirements should be related only to
the number of passengers carried. The FAA disagrees. The emergency
lighting requirements are not dependent solely on the number of
passengers carried, but are a fundamental aspect of improving cabin
safety in emergency evacuations.
Another commenter states that Sec. 23.812(f)(2) implies the use of
an inertia switch to activate emergency lighting. The commenter adds
that the history of these devices has been poor and the commenter is
not convinced of their worth. The FAA disagrees. The use of an inertia
switch was not implied in the proposal. The FAA is not mandating the
use of specific products in this rulemaking action but rather is
addressing an airworthiness requirement. How the applicant chooses to
comply with that requirement is left entirely to the applicant.
Another commenter strongly favors emergency lighting but believes
that requirements should be adapted for small commuter category
airplanes. The commenter suggests that the proposed rule is acceptable
through Sec. 23.812(g) and adds that Sec. 23.812(h) should be modified
to require bright lights at the emergency exits inside the airplane and
outside the exits other than floor level doors.
The FAA disagrees. As proposed these requirements are suitable for
the small commuter airplanes and are consistent with the requirements
for similarly sized small transport category airplanes.
The same commenter suggests that the floor proximity emergency
escape path marking is unnecessary and that Sec. 23.812(h)(3) should be
deleted.
The FAA disagrees. Floor proximity emergency escape path marking is
intended to allow passengers, who have become oriented within the cabin
during the period of general overhead illumination, to find their way
to exits unassisted after the general overhead illumination becomes
obscured. There are many combinations of lights, markers, and signs
that might serve this objective, and each must be shown adequate for
the particular cabin interior and exit arrangement; therefore, this
performance standard is used to allow design flexibility and ensure the
necessary safety.
The same commenter adds that the requirements of Sec. 23.812(i)
through Sec. 23.812(l), are acceptable; however, general illumination
is not necessary, and Sec. 23.812(l)(1) should probably specify 50
percent instead of 75 percent illumination. General illumination
requirements are considered to be an essential element in the standards
for providing adequate lighting for the airplane occupants to reach,
operate, and egress through the entry door or the emergency exits in
emergency situations when the normal interior lighting has been
rendered inoperative.
This proposed emergency lighting standard was developed with
consideration for: emergency lighting standards used for small
transport airplanes; additional airworthiness requirements applied to
commuter category airplanes when exemptions to the requirements of
Secs. 23.807(d)(1) (i) or (ii), were granted; and the need to ensure
that the ability to egress a commuter category airplane is maintained
when the number of emergency exits is fewer than the number required by
Secs. 23.807(d)(1) (i) or (ii). It is not necessary to require that all
lights, except those directly damaged by the fuselage breakup, remain
operative after any single vertical separation of the fuselage during a
crash landing. The FAA considers the present requirement that permits
25 percent of certain emergency lights, in addition to those directly
damaged by the fuselage breakup, to be rendered inoperative
(Sec. 23.812(l)(2)) adequate to accomplish safe evacuation. This
proposal is adopted as proposed.
Proposal 9. This proposal would add requirements to ensure
emergency exit accessibility when an applicant for type certification
chooses to comply with the alternative emergency exit provisions of
proposed Sec. 23.807(d)(4). Structural failures or yielding of the
airframe can occur during an emergency landing or a crash event and may
result in one or more emergency exits or the passenger door being
rendered unusable. Since the total number of exits available for
emergency egress can be fewer with the alternate emergency exit
requirements, this proposal defines minimum unobstructed aisle width at
the passenger entry door. This proposal would also add other
requirements to ensure that any partitions or doorways within the
passenger compartment do not hinder occupant access to the exits during
an emergency situation.
One commenter suggests that the proposal needs to be clarified so
that the lavatory compartment, with a seat approved for use during
takeoff and landing, is not considered to be a passenger compartment
prohibited from having a door installed between it and the remainder of
the passenger compartment. The commenter believes that the provisions
of Sec. 23.813(b)(5) provide an adequate and equivalent level of safety
whenever doors are installed and that Sec. 23.813(b)(4) should be
deleted.
The FAA agrees that clarification of Sec. 23.813(b)(4) and
Sec. 23.813(b)(5) is needed. Accordingly, after the semicolon following
``compartments'' in Sec. 23.813(b)(4), the word ``and'' will be
deleted. The remaining part of the paragraph will read, ``unless the
door has a means to latch it in the open position. The latching means
must be able to withstand the loads imposed upon it by the door when
the door is subjected to the inertia loads resulting from the ultimate
static load factors prescribed in Sec. 23.561(b)(2).'' Proposed
Sec. 23.813(b)(5) is adopted with the change noted above.
Two commenters suggest that proposed Sec. 23.813(b)(2) be deleted
because it is not appropriate to small airplanes that do not use cabin
attendants. The FAA disagrees. Since not all exits may be operational
during an emergency evacuation, the intent of the rule is to ensure
minimum unobstructed aisle width and passenger entryways in order to
maintain occupant access to exits. The term ``assistance,'' as used in
the proposal, does not necessarily mean cabin attendants. This proposal
is adopted with the aforementioned changes.
Proposal 10. This proposal would require increased aisle widths
when an applicant for type certification chooses to comply with the
alternative emergency exit provisions of proposed Sec. 23.807(d)(4).
The proposed increased aisle width requirements are intended to ensure
that the airplane passengers can reach an exit in an emergency
situation even though the floor structure has been warped or there are
seats or other items protruding into the normal aisle space.
One commenter supports the establishment of 12 inches as the
minimum aisle width and is against allowing aisles as narrow as 9
inches in certain cases. The commenter feels that there is never a time
when such a narrow aisle is appropriate. The FAA disagrees. Service
experience in small transport category airplanes with a passenger
seating capacity of 10 or fewer and an aisle width not less than 9
inches has been found satisfactory.
One commenter states that the expanded aisle widths would cause an
increase in the fuselage width of most commuter airplanes and that the
proposal would, in most cases, negate the use of any alternate
emergency exit provisions. The comment does not reveal whether the
commenter has considered that variations in seating layout for new
designs would accommodate the requirement and the commenter has
supplied no data to support this contention.
One commenter states that, with two abreast seating, aisle width
requirements do not control passenger flow in an emergency evacuation.
The commenter suggests that if the FAA has evidence that aisle width
restricts passenger flow when three abreast seating is used, then the
proposed Sec. 23.815(b) should be made applicable only to such
arrangements. The commenter adds that the FAA should consider that
proposed Sec. 23.815(b) would discriminate against airplanes with two
abreast seating because the increased aisle width is generally
impractical.
The FAA disagrees. The purpose of the increased aisle width is to
increase the probability that occupants can reach an exit during an
emergency situation, even though seats or other items may be protruding
into the normal aisle space. It is recognized that changes in aisle
width have little significant effect on evacuation if minimum
airworthiness standards for cabin safety and emergency exits are first
met. However, part of the intent of this amendment is to establish
these minimum alternative requirements for part 23 commuter category
airplanes consistent with those for part 25 small transport category
airplanes. This proposal is adopted as proposed.
Final Regulatory Evaluation, Final Regulatory Flexibility
Determination, and Trade Impact Assessment
Proposed changes to Federal regulations must undergo several
economic analyses. First, Executive Order 12866 directs that each
Federal agency shall propose or adopt a regulation only upon a reasoned
determination that the benefits of the intended regulation justify its
costs. Second, the Regulatory Flexibility Act of 1980 requires agencies
to analyze the economic effect of regulatory changes on small entities.
Third, the Office of Management and Budget directs agencies to assess
the effects of regulatory changes on international trade. In conducting
these analyses, the FAA has determined that this rule: (1) Will
generate benefits that justify its costs and is not a ``significant
regulatory action'' as defined in the Executive Order; (2) is not
``significant'' as defined in DOT's Policies and Procedures; (3) will
not have a significant impact on a substantial number of small
entities; and (4) will not constitute a barrier to international trade.
These analyses, available in the docket, are summarized below.
Regulatory Evaluation Summary
Flightcrew Exit
Few airplane models will likely be affected by this part of the
rule. For purposes of illustrating representative costs, it is assumed
that one new model will be type certificated three years following the
effective date of the rule and that 10 airplanes will be manufactured
annually during a ten-year production run, each with an average
operating life of 25 years. The FAA estimates that the additional exit
will cost $7,300 per airplane, totalling $730,000. Increased fuel cost
resulting from the added weight of the exit is estimated to be $200 per
airplane per year, totalling $500,000. These costs total $1,230,000, or
$525,000 discounted at seven percent to present value.
Historical accident data do not reveal that crewmember fatalities
have occurred as a result of inability to exit cargo-laden airplanes in
otherwise survivable accidents. However, such an occurrence is a
possibility. As applied to the above representative certification, the
additional flightcrew exits would be cost beneficial if only one
fatality was prevented. For the purpose of quantifying benefits, the
FAA currently uses a minimum value of $2,600,000 to statistically
represent a human fatality avoided.
Emergency Ditching Requirements
Most current multiengine airplane models would satisfy the ditching
requirements of the rule. Future models with side exits above the
waterline will experience little or no incremental costs. However,
designs with overhead emergency exits in lieu of side exits above the
waterline would cost approximately $11,000 per airplane, totalling
$1,100,000 (using the same production run and service life assumptions
used above). Increased fuel cost resulting from added weight is
estimated to be $300 per airplane per year, totalling $750,000. These
costs total $1,850,000, or $790,000 discounted.
Historical accident data indicate that between 1975 and 1991, 14
multiengine commuter airplanes experienced an emergency forced landing
in water, resulting in 43 fatalities in total. Although there is no
evidence that the fatalities occurred solely because the available
emergency exits were below the waterline (hence making it difficult if
not impossible to exit the airplane), such a situation is a distinct
possibility absent the new requirements. As applied to the above type
certification, the modified emergency exits would be cost-beneficial if
only two fatalities were prevented.
Remaining Provisions of the Rule
With the exception of the provisions related to the flightcrew exit
and emergency ditching, the rule changes will not result in additional
costs to manufacturers. Most of the changes will provide manufacturers
of certain commuter category airplanes with a choice of either:
(1) Designing to current Part 23 cabin safety standards which
require two emergency exits (in addition to the passenger entry door)
for airplanes with a total passenger seating capacity of 15 or fewer,
or three emergency exits (in addition to the passenger entry door) for
airplanes with a total passenger seating capacity of 16 to 19; or
(2) Designing to the alternative Part 23 standards that mirror the
current requirements for Part 25 small transport category airplanes
requiring only one exit (in addition to the passenger entry door) for
airplanes with a passenger seating capacity of 19 or fewer, and also
requiring many other cabin safety improvements that are not currently
required for Part 23 commuter airplanes.
A manufacturer would choose the alternative that is more cost-
effective. A nonquantifiable benefit of this rule is that it will make
the cabin safety requirements of commuter category airplanes consistent
with those of small transport category airplanes of similar passenger
capacities.
Regulatory Flexibility Determination
The Regulatory Flexibility Act of 1980 (RFA) was enacted by
Congress to ensure that small entities are not unnecessarily and
disproportionately burdened by government regulations. The RFA requires
agencies to review rules which may have ``a significant economic impact
on a substantial number of small entities.''
As defined by implementing FAA Order 2100.14A, the size threshold
for designating an aircraft manufacturer a small entity is 75
employees; that is, an aircraft manufacturer with more than 75
employees is not considered to be a small entity. A substantial number
of small entities is defined as a number which is not fewer than 11 and
which is more than one-third of the small entities subject to the rule.
Since there are fewer than 11 small airplane manufacturers that will be
affected by the new requirements, the rule will not have a significant
economic impact on a substantial number of small entities.
International Trade Impact Assessment
The rule will have little or no impact on trade for either American
firms doing business in foreign countries or foreign firms doing
business in the United States. In the United States, foreign
manufacturers will have to meet U.S. requirements, and thus will gain
no competitive advantage. In foreign countries, American manufacturers
need not comply with these requirements if the foreign country does not
require them and, therefore, will not be placed at a competitive
disadvantage relative to foreign manufacturers.
Federalism Implications
The regulations herein will not have substantial direct effects on
the States, on the relationship between the national government and the
States, or on the distribution of power and responsibilities among the
various levels of government. Therefore, in accordance with Executive
Order 12612, it is determined that this final rule does not have
federalism implications to warrant the preparation of a Federalism
Assessment.
Conclusion
This final rule upgrades the emergency egress requirements of the
airworthiness standards for normal, utility, acrobatic, and commuter
category airplanes. Applicants seeking new type certification for all
airplane categories will be required to provide for ditching and
flightcrew emergency exits to ensure that emergency exits are available
to all flightcrew members and that emergency exits are available to all
multiengine airplane occupants during an emergency landing in water. In
addition, this final rule provides an applicant seeking type
certification for commuter category airplanes the option of meeting
exit requirements that are consistent with the existing transport
category standards.
For the reasons discussed in the preamble, and based on the
findings in the Regulatory Evaluation, the FAA has determined that this
regulation is nonsignificant under Executive Order 12866. In addition,
the FAA certifies that this regulation will not have a significant
economic impact, positive or negative, on a substantial number of small
entities. This regulation is not considered significant under DOT
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979). A
regulatory evaluation of the regulation has been placed in the docket.
A copy may be obtained by contacting the person identified under FOR
FURTHER INFORMATION CONTACT.
List of Subjects in 14 CFR Part 23
Aircraft, Aviation safety, Signs and symbols.
Issued in Washington, DC on May 11, 1994.
David R. Hinson,
Administrator.
The Amendment
In consideration of the foregoing, the Federal Aviation
Administration amends part 23 of the Federal Aviation Regulations (14
CFR part 23) as follows:
PART 23--AIRWORTHINESS STANDARDS: NORMAL, UTILITY, ACROBATIC, AND
COMMUTER CATEGORY AIRPLANES
1. The authority citation for part 23 continues to read as follows:
Authority: 49 U.S.C. 1344, 1354(a), 1355, 1421, 1423, 1425,
1428, 1429, 1430; 49 U.S.C. 106(g).
2. Section 23.561 is amended by adding a new paragraph (b)(2)(iv)
to read as follows:
Sec. 23.561 General.
* * * * *
(b) * * *
(2) * * *
(iv) Downward, 6.0g when certification to the emergency exit
provisions of Sec. 23.807(d)(4) is requested; and
* * * * *
3. Section 23.783 is amended by adding a new paragraph (f) to read
as follows:
Sec. 23.783 Doors.
* * * * *
(f) In addition, for commuter category airplanes, the following
requirements apply:
(1) Each passenger entry door must qualify as a floor level
emergency exit. This exit must have a rectangular opening of not less
than 24 inches wide by 48 inches high, with corner radii not greater
than one-third the width of the exit.
(2) If an integral stair is installed at a passenger entry door,
the stair must be designed so that, when subjected to the inertia loads
resulting from the ultimate static load factors in Sec. 23.561(b)(2)
and following the collapse of one or more legs of the landing gear, it
will not reduce the effectiveness of emergency egress through the
passenger entry door.
4. Section 23.803 is amended by designating the existing text as
paragraph (a), and by adding a new paragraph (b) to read as follows:
Sec. 23.803 Emergency evacuation.
* * * * *
(b) In addition, when certification to the emergency exit
provisions of Sec. 23.807(d)(4) is requested, only the emergency
lighting system required by Sec. 23.812 may be used to provide cabin
interior illumination during the evacuation demonstration required in
paragraph (a) of this section.
5. A new Sec. 23.805 is added to read as follows:
Sec. 23.805 Flightcrew emergency exits.
For airplanes where the proximity of the passenger emergency exits
to the flightcrew area does not offer a convenient and readily
accessible means of evacuation for the flightcrew, the following apply:
(a) There must be either one emergency exit on each side of the
airplane, or a top hatch emergency exit, in the flightcrew area;
(b) Each emergency exit must be located to allow rapid evacuation
of the crew and have a size and shape of at least a 19- by 20-inch
unobstructed rectangular opening; and
(c) For each emergency exit that is not less than six feet from the
ground, an assisting means must be provided. The assisting means may be
a rope or any other means demonstrated to be suitable for the purpose.
If the assisting means is a rope, or an approved device equivalent to a
rope, it must be--
(1) Attached to the fuselage structure at or above the top of the
emergency exit opening or, for a device at a pilot's emergency exit
window, at another approved location if the stowed device, or its
attachment, would reduce the pilot's view; and
(2) Able (with its attachment) to withstand a 400-pound static
load.
6. Section 23.807 is amended by revising paragraphs (d)
introductory text and (d)(1), and by adding paragraphs (d)(3), (d)(4),
and (e) to read as follows:
Sec. 23.807 Emergency exits.
* * * * *
(d) Doors and exits. In addition, for commuter category airplanes,
the following requirements apply:
(1) In addition to the passenger entry door--
(i) For an airplane with a total passenger seating capacity of 15
or fewer, an emergency exit, as defined in paragraph (b) of this
section, is required on each side of the cabin; and
(ii) For an airplane with a total passenger seating capacity of 16
through 19, three emergency exits, as defined in paragraph (b) of this
section, are required with one on the same side as the passenger entry
door and two on the side opposite the door.
* * * * *
(3) Each required emergency exit, except floor level exits, must be
located over the wing or, if not less than six feet from the ground,
must be provided with an acceptable means to assist the occupants to
descend to the ground. Emergency exits must be distributed as uniformly
as practical, taking into account passenger seating configuration.
(4) Unless the applicant has complied with paragraph (d)(1) of this
section, there must be an emergency exit on the side of the cabin
opposite the passenger entry door, provided that--
(i) For an airplane having a passenger seating configuration of
nine or fewer, the emergency exit has a rectangular opening measuring
not less than 19 inches by 26 inches high with corner radii not greater
than one-third the width of the exit, located over the wing, with a
step up inside the airplane of not more than 29 inches and a step down
outside the airplane of not more than 36 inches;
(ii) For an airplane having a passenger seating configuration of 10
to 19 passengers, the emergency exit has a rectangular opening
measuring not less than 20 inches wide by 36 inches high, with corner
radii not greater than one-third the width of the exit, and with a step
up inside the airplane of not more than 20 inches. If the exit is
located over the wing, the step down outside the airplane may not
exceed 27 inches; and
(iii) The airplane complies with the additional requirements of
Secs. 23.561(b)(2)(iv), 23.803(b), 23.811(c), 23.812, 23.813(b), and
23.815.
(e) For multiengine airplanes, ditching emergency exits must be
provided in accordance with the following requirements, unless the
emergency exits required by paragraph (a) or (d) of this section
already comply with them:
(1) One exit above the waterline on each side of the airplane
having the dimensions specified in paragraph (b) or (d) of this
section, as applicable; and
(2) If side exits cannot be above the waterline, there must be a
readily accessible overhead hatch emergency exit that has a rectangular
opening measuring not less than 20 inches wide by 36 inches long, with
corner radii not greater than one-third the width of the exit.
7. Section 23.811 is amended by adding a new paragraph (c) to read
as follows:
Sec. 23.811 Emergency exit marking.
* * * * *
(c) In addition, when certification to the emergency exit
provisions of Sec. 23.807(d)(4) is requested, the following apply:
(1) Each emergency exit, its means of access, and its means of
opening, must be conspicuously marked;
(2) The identity and location of each emergency exit must be
recognizable from a distance equal to the width of the cabin;
(3) Means must be provided to assist occupants in locating the
emergency exits in conditions of dense smoke;
(4) The location of the operating handle and instructions for
opening each emergency exit from inside the airplane must be shown by
marking that is readable from a distance of 30 inches;
(5) Each passenger entry door operating handle must--
(i) Be self-illuminated with an initial brightness of at least 160
microlamberts; or
(ii) Be conspicuously located and well illuminated by the emergency
lighting even in conditions of occupant crowding at the door;
(6) Each passenger entry door with a locking mechanism that is
released by rotary motion of the handle must be marked--
(i) With a red arrow, with a shaft of at least three-fourths of an
inch wide and a head twice the width of the shaft, extending along at
least 70 degrees of arc at a radius approximately equal to three-
fourths of the handle length;
(ii) So that the center line of the exit handle is within
one inch of the projected point of the arrow when the
handle has reached full travel and has released the locking mechanism;
(iii) With the word ``open'' in red letters, one inch high, placed
horizontally near the head of the arrow; and
(7) In addition to the requirements of paragraph (a) of this
section, the external marking of each emergency exit must--
(i) Include a 2-inch colorband outlining the exit; and
(ii) Have a color contrast that is readily distinguishable from the
surrounding fuselage surface. The contrast must be such that if the
reflectance of the darker color is 15 percent or less, the reflectance
of the lighter color must be at least 45 percent. ``Reflectance'' is
the ratio of the luminous flux reflected by a body to the luminous flux
it receives. When the reflectance of the darker color is greater than
15 percent, at least a 30 percent difference between its reflectance
and the reflectance of the lighter color must be provided.
8. A new Sec. 23.812 is added to read as follows:
Sec. 23.812 Emergency lighting.
When certification to the emergency exit provisions of
Sec. 23.807(d)(4) is requested, the following apply:
(a) An emergency lighting system, independent of the main cabin
lighting system, must be installed. However, the source of general
cabin illumination may be common to both the emergency and main
lighting systems if the power supply to the emergency lighting system
is independent of the power supply to the main lighting system.
(b) There must be a crew warning light that illuminates in the
cockpit when power is on in the airplane and the emergency lighting
control device is not armed.
(c) The emergency lights must be operable manually from the
flightcrew station and be provided with automatic activation. The
cockpit control device must have ``on,'' ``off,'' and ``armed''
positions so that, when armed in the cockpit, the lights will operate
by automatic activation.
(d) There must be a means to safeguard against inadvertent
operation of the cockpit control device from the ``armed'' or ``on''
positions.
(e) The cockpit control device must have provisions to allow the
emergency lighting system to be armed or activated at any time that it
may be needed.
(f) When armed, the emergency lighting system must activate and
remain lighted when--
(1) The normal electrical power of the airplane is lost; or
(2) The airplane is subjected to an impact that results in a
deceleration in excess of 2g and a velocity change in excess of 3.5
feet-per-second, acting along the longitudinal axis of the airplane; or
(3) Any other emergency condition exists where automatic activation
of the emergency lighting is necessary to aid with occupant evacuation.
(g) The emergency lighting system must be capable of being turned
off and reset by the flightcrew after automatic activation.
(h) The emergency lighting system must provide internal lighting,
including--
(1) Illuminated emergency exit marking and locating signs,
including those required in Sec. 23.811(b);
(2) Sources of general illumination in the cabin that provide an
average illumination of not less than 0.05 foot-candle and an
illumination at any point of not less than 0.01 foot-candle when
measured along the center line of the main passenger aisle(s) and at
the seat armrest height; and
(3) Floor proximity emergency escape path marking that provides
emergency evacuation guidance for the airplane occupants when all
sources of illumination more than 4 feet above the cabin aisle floor
are totally obscured.
(i) The energy supply to each emergency lighting unit must provide
the required level of illumination for at least 10 minutes at the
critical ambient conditions after activation of the emergency lighting
system.
(j) If rechargeable batteries are used as the energy supply for the
emergency lighting system, they may be recharged from the main
electrical power system of the airplane provided the charging circuit
is designed to preclude inadvertent battery discharge into the charging
circuit faults. If the emergency lighting system does not include a
charging circuit, battery condition monitors are required.
(k) Components of the emergency lighting system, including
batteries, wiring, relays, lamps, and switches, must be capable of
normal operation after being subjected to the inertia forces resulting
from the ultimate load factors prescribed in Sec. 23.561(b)(2).
(l) The emergency lighting system must be designed so that after
any single transverse vertical separation of the fuselage during a
crash landing:
(1) At least 75 percent of all electrically illuminated emergency
lights required by this section remain operative; and
(2) Each electrically illuminated exit sign required by Sec. 23.811
(b) and (c) remains operative, except those that are directly damaged
by the fuselage separation.
9. Section 23.813 is amended by designating the existing text as
paragraph (a), and by adding a new paragraph (b) to read as follows:
Sec. 23.813 Emergency exist access.
* * * * *
(b) In addition, when certification to the emergency exit
provisions of Sec. 23.807(d)(4) is requested, the following emergency
exit access must be provided:
(1) The passageway leading from the aisle to the passenger entry
door must be unobstructed and at least 20 inches wide.
(2) There must be enough space next to the passenger entry door to
allow assistance in evacuation of passengers without reducing the
unobstructed width of the passageway below 20 inches.
(3) If it is necessary to pass through a passageway between
passenger compartments to reach a required emergency exit from any seat
in the passenger cabin, the passageway must be unobstructed; however,
curtains may be used if they allow free entry through the passageway.
(4) No door may be installed in any partition between passenger
compartments unless that door has a means to latch it in the open
position. The latching means must be able to withstand the loads
imposed upon it by the door when the door is subjected to the inertia
loads resulting from the ultimate static load factors prescribed in
Sec. 23.561(b)(2).
(5) If it is necessary to pass through a doorway separating the
passenger cabin from other areas to reach a required emergency exit
from any passenger seat, the door must have a means to latch it in the
open position. The latching means must be able to withstand the loads
imposed upon it by the door when the door is subjected to the inertia
loads resulting from the ultimate static load factors prescribed in
Sec. 23.561(b)(2).
10. Section 23.815 is amended by designating the existing text as
paragraph (a); by amending newly designated paragraph (a) by removing
the word ``For'' and adding in its place the words ``Except as provided
in paragraph (b) of this section, for''; and by adding a new paragraph
(b) to read as follows:
Sec. 23.815 Width of aisle.
* * * * *
(b) When certification to the emergency exist provisions of
Sec. 23.807(d)(4) is requested, the main passenger aisle width at any
point between the seats must equal or exceed the following values:
------------------------------------------------------------------------
Minimum main passenger
aisle width (inches)
-------------------------
Number of passenger seats Less than 25 inches
25 inches and more
from floor from floor
------------------------------------------------------------------------
10 or fewer................................... \1\12 15
11 through 19................................. 12 20
------------------------------------------------------------------------
\1\A narrower width not less than 9 inches may be approved when
substantiated by tests found necessary by the Administrator.
[FR Doc. 94-11847 Filed 5-16-94; 8:45 am]
BILLING CODE 4910-13-M
