Airworthiness Standards; Emergency Exit Provisions for Normal, Utility, Acrobatic, and Commuter Category Airplanes; Final Rule DEPARTMENT OF TRANSPORTATION

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 The proposal was withdrawn because it was not cost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