[Federal Register Volume 61, Number 218 (Friday, November 8, 1996)]
[Rules and Regulations]
[Pages 57946-57958]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-28650]



[[Page 57945]]

_______________________________________________________________________

Part II





Department of Transportation





_______________________________________________________________________



Federal Aviation Administration



_______________________________________________________________________



14 CFR Part 25



Type and Number of Passenger Emergency Exits Required in Transport 
Category Airplanes; Interim Rule

  Federal Register / Vol. 61, No. 218 / Friday, November 8, 1996 / 
Rules and Regulations  

[[Page 57946]]



DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 25

[Docket No. 26140; Amendment No. 25-88]
RIN 2120-AC43


Type and Number of Passenger Emergency Exits Required in 
Transport Category Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

-----------------------------------------------------------------------

SUMMARY: This amendment defines two new types of passenger emergency 
exits in transport category airplanes, provides more consistent 
standards with respect to the passenger seating allowed for each exit 
type and combination of exit types, and requires escape slides to be 
erected in less time. These changes allow more flexibility in the 
design of emergency exits and reflect recent improvements in escape 
slide technology. They will enable more cost-effective emergency exit 
arrangements and, in the case of escape slides, enable more rapid 
egress of passengers under emergency conditions.

EFFECTIVE DATE: December 9, 1996.

FOR FURTHER INFORMATION CONTACT: Gary L. Killion, Manager, Regulations 
Branch (ANM-114), Transport Standards Staff, Transport Airplane 
Directorate, Aircraft Certification Service, FAA, 1601 Lind Ave. SW., 
Renton, WA 98055-4056; telephone (206) 227-2194.

SUPPLEMENTARY INFORMATION:

Background

    This amendment is based on Notice of Proposed Rulemaking (NPRM) No. 
90-4 which was published in the Federal Register on February 22, 1990 
(55 FR 6344). In that notice, the FAA proposed amendments to 14 CFR 
part 25 that would revise the current requirements for the passenger 
emergency exits of transport category airplanes and define two new exit 
types. In addition, the FAA also proposed to require escape slides to 
be erected in less time, a reflection of improvements in escape slide 
state-of-the-art.
    Since the time Notice No. 90-4 was published, a number of 
amendments were adopted. The changes adopted with Amendment 25-72 (55 
FR 29781, July 20, 1990) are largely nonsubstantive in nature; however, 
the editorial structure of the sections involved in the proposals of 
Notice No. 90-4 was changed considerably. The changes adopted with 
Amendment 25-76 (57 FR 19220, May 4, 1992) do not have any substantive 
bearing on those proposed in Notice 90-4; however, they also affect the 
editorial structure of those sections. Where pertinent, the effect of 
those amendments on the changes proposed in Notice 90-4 is discussed 
below. None of the other amendments adopted during this period have any 
bearing on the proposals of Notice No. 90-4.

Current Requirements of Part 25

    Part 25 currently defines seven types of passenger emergency exits 
for transport category airplanes--Type A, Types I through IV, tail cone 
and ventral. As defined in Sec. 25.807, exits in fuselage sides range 
in size from large Type A exits, which must be a minimum of 42 inches 
wide by 72 inches high, to Type IV exits, which must be a minimum of 19 
inches wide by 26 inches high. Although an exit may exceed the minimum 
dimensions specified for a particular type, it is considered to be of 
that type unless it qualifies in all respects as one of the larger exit 
types. Typically, the larger exits are hinged or translating doors 
while the smaller exits are typically removable hatches.
    Section 25.809(b)(2) requires that each emergency exit must be 
capable of being opened, when there is no fuselage deformation, within 
10 seconds measured from the time when the opening means is actuated to 
the time when the exit if fully opened.
    It must be emphasized that, except for tail-cone or ventral exits, 
all references to the types and numbers of required passenger emergency 
exits in part 25 and this final rule refer to the exits required in 
each side of the fuselage, not the total for the airplane. Although 
they are not required to be symmetrical, corresponding exits on 
opposite sides of the fuselage are usually referred to as ``exit 
pairs'' to preclude confusion between the total number of exits and the 
number of exits on each side. The number of additional passenger seats 
that may be installed for each additional exit pair of a specific type 
is sometimes referred to as the ``exit rating'' for that type. When an 
``exit pair'' consists of two different types of exits, the exits are 
both considered to be of the type with the smaller exit rating. 
Generally, no credit is given for an exit on one side with no 
corresponding exit on the other side. (Even though no credit is given 
to such exits, they are required to meet all applicable exit design 
requirements because they may be used by occupants under emergency 
conditions.)
    Note that the standards of part 25, including those for emergency 
evacuation demonstrations as well as those concerning types and numbers 
of exits, are based on the assumption that only half of the exits will 
be usable during an actual emergency due to fire, structural damage or 
other adverse circumstance.
    Section 25.807(d) currently specifies the type and number of 
emergency exits required for three ranges of passenger seating 
capacities. The first range, passenger seating configurations of one to 
179, is addressed in Sec. 25.807(d)(1) in a table that outlines the 
specific type and number of exits that must be provided. Those 
standards have been in effect for several decades and were based more 
on industry practice during the reciprocating-engine transport airplane 
era than on any particular testing.
    For the second range, passenger seating configurations of 180 to 
299, Sec. 25.807(d)(1) uses a different approach. Instead of specifying 
the type and number of exits required for those airplanes, a second 
table supplements the first by specifying the number of passenger 
seats, in addition to 179, that may be installed for various types of 
additional exits. For example, the first table specifies that an 
airplane with 179 passenger seats must have two pairs of Type I exits 
and two pairs of Type III exits. The second table specifies that the 
seating may be increased by 45 passengers for each additional pair of 
Type I exits installed. An airplane with three pairs of Type I exits 
and two pairs of Type III exits would, therefore, be permitted, insofar 
as the type and number of exits is concerned, to have a passenger 
seating configuration of 224.
    For the third range, passenger seating configurations greater than 
299, Sec. 25.807(d)(2) simply states that each exit installed in the 
side of the fuselage must be either a Type I or Type A exit and that 
seating configurations of 45 and 110 are allowed for each pair of Type 
I exits and each pair of Type A exits, respectively.
    Section 25.807(d)(3) specifies the number of additional passenger 
seats that may be provided when creditable ventral or tail-cone exits 
are installed. In order to receive any credit as a passenger emergency 
exit, a ventral or tail-cone exit must provide the same rate of egress 
as a Type III exit with the airplane in the most adverse exit opening 
condition that would result from the collapse of one or more landing 
gear legs.
    As amended recently by Amendment 25-72, Sec. 25.807(d)(5) provides 
flexibility in the type and number of exits required by stating that an 
alternate emergency exit configuration may be approved in lieu of that 
specified in either Sec. 25.807(d) (1) or (2) provided the

[[Page 57947]]

overall evacuation capability is shown to be equal to or greater than 
that of the specified emergency exit configuration. This means, for 
example, that one pair of larger exits could be substituted in some 
cases for two pairs of smaller exits.
    Providing the type and number of exits specified for a given number 
of passenger seats does not, in itself, ensure that an airplane can be 
approved with that many seats. Other requirements, such as uniform 
distribution of passenger seats and exits and the demonstrated 
emergency evacuation capability, may actually limit seating to fewer 
passengers.
    Part 25 specifies that a means must be provided to assist 
passengers in descending to the ground for each exit, other than an 
overwing exit, that is more than six feet from the ground when the 
airplane is on the ground with the landing gear extended. Section 
25.810(a)(1)(i) specifies that the assist means must be deployed 
automatically and that deployment must begin during the interval 
between the time the exit opening means is actuated from inside the 
airplane and the time the exit is fully opened. As noted above, that 
time interval must be no more than 10 seconds. Section 25.810(a)(1)(ii) 
further specifies that the assist means must be automatically erected 
within 10 seconds after deployment is begun. Taking the maximum time 
intervals permitted, the assist means must be erected and usable no 
more than 20 seconds after the exit opening means is actuated. 
Generally, inflatable slides are used for this purpose.
    For an overwing exit, Sec. 25.810(d) specifies that a means must be 
provided to assist passengers in descending to the ground whenever the 
place on the airplane structure at which the escape route terminates 
(typically the trailing edge of a wing flap) is more than six feet from 
the ground. Inflatable slides are generally used for this purpose also. 
Part 25 currently contains no specific maximum erection time for off-
wing slides; however, Technical Standard Order (TSO) C69b, which 
contains design standards for inflatable escape slides, specifies that 
off-wing escape slides must be fully erect within 10 seconds after 
actuation of the inflation controls. (TSO-C69a, which was superseded by 
TSO-C69b on August 17, 1988, had previously a maximum erection time of 
15 seconds.)
    Because the large Type A emergency exits are expected to 
accommodate parallel lines of evacuees simultaneously, 
Sec. 25.810(a)(1) specifies that the means provided for those exits to 
assist the occupants in descending to the ground must also be capable 
of carrying two parallel lines of evacuees simultaneously.
    Section 25.813(b) requires adequate space next to one side of each 
emergency exit, other than a Type A exit, that is required by 
Sec. 25.810(a) to have an assist means to allow crewmembers to assist 
in the evacuation. Because there are two parallel lines of evacuees to 
assist, each Type A emergency exit is required to have an assist space 
on each side of the exit. Unlike other exit types, Type A exits must 
have such assist space regardless of whether the exit is required to 
have an assist means. At the time Notice 90-4 was issued, the latter 
requirement was contained in Sec. 25.807(a)(7)(vii); however, it has 
since been consolidated with the former in Sec. 25.813(b) (Amendment 
25-72).

Amendments Proposed in Notice 90-4

    The FAA held a public technical conference in Seattle, Washington, 
in September 1985, to review the existing safety regulations and 
practices regarding the emergency evacuation of transport airplanes. As 
a result of the conference, it was recommended, in part, that the 
regulations relative to passenger emergency exits be revised to provide 
design flexibility, and those concerning escape slide inflation time be 
revised to reflect the current state-of-the-art. Subsequent to this 
public conference, the following changes were proposed in Notice 90-4:

Type and Number of Emergency Exits

    Unlike the standards for airplanes with more than 299 seats, the 
number of additional passenger seats allowed for smaller passenger 
capacities is not uniform. For example, the first table of 
Sec. 25.807(d)(1) (Sec. 25.807(c) prior to Amendment 25-72) requires a 
pair of Type I exits and a pair of Type III exits for a maximum 
passenger seating capacity of 79. Adding another pair of Type I exits, 
resulting in a total of two pairs of Type I exits and one pair of Type 
III exits, would allow up to 139 passenger seats--an increase of 60 
attributable to the additional pair of Type I exits. In contrast, one 
pair of Type I exits and two pairs of Type III exits are required for a 
maximum seating configuration of 109. Adding another pair of Type I 
exits in that case, resulting in a total of two pairs of Type I exits 
and two pairs of Type III exits, would allow up to 179 passengers--an 
increase of 70 attributable to the additional pair of Type I exits. For 
configurations beyond 179 passengers, the second table of 
Sec. 25.807(d)(1) allows an increase of only 45 for each additional 
pair of Type I exits. Thus the increase in the number of passenger 
seats allowed, if one additional pair of Type I exits were installed, 
varies from 45 to 70, depending on the initial airplane exit 
configuration and the total passenger seating capacity.
    The additional passenger seating capacity gained by adding a pair 
of Type III exits varies in a similar manner. The first table of 
Sec. 25.807(d)(1) currently allows 79 passenger seats if one pair of 
Type I and one pair of Type III exits are installed. If one more pair 
of Type III exits were installed, the allowable number of passenger 
seats would be increased by 30 to a total of 109 passenger seats. In 
contrast, two pair of Type I exits and one pair of Type III exits are 
currently required for a maximum seating capacity of 139. Adding a pair 
of Type III exits would allow a maximum seating capacity of 179, an 
increase of 40 passenger seats. For configurations beyond 179 
passengers, the second table of Sec. 25.807(d) allows an increase of 35 
passenger seats for each additional pair of Type III exits.
    When the exit configurations and maximum passenger capacities 
specified in the first table of Sec. 25.807(d)(1) are compared with the 
combined ratings specified in the second table of Sec. 25.807(d)(2) for 
the same combination of exit types, it can be seen that the maximum 
capacities for the first two configurations (19 and 39 passengers) are 
conservative when compared to the assigned ratings. They are in close 
agreement for the next two configurations (79 and 109) and generous for 
the two largest configurations (139 and 170). A similar comparison can 
not be made for Type IV exits since no ratings are established for 
those exits in the second table.
    As proposed in Notice 90-4, Sec. 25.807 would be revised to provide 
one simple, consistent set of standards while still retaining an 
equivalent level of safety. The exit ratings for Type I, Type II, Type 
III and Type A exits would be the same as those currently shown in the 
second table of Sec. 25.807(d)(1) for those types. Type IV exits would 
be assigned a passenger rating of nine to be consistent with the 
maximum passenger capacity currently shown in the first table of 
Sec. 25.807(d)(1). Replacing the exiting tables with specific ratings 
for each type of exit would enable the airplane manufacturer to design 
an airplane with any combination of exits the manufacturer chooses, 
subject to specific constraints. The following constraints, which would 
be contained in Sec. 25.807(g), were proposed to ensure that the margin 
of safety currently

[[Page 57948]]

associated with passenger capacities of approximately 40 and fewer 
passenger seats would be retained and that there would be no 
significant increases in passenger seating permissible with the various 
combinations of exit types. In addition, unacceptable alternative 
combinations of exits, such as one pair of Type A exits and three pairs 
of Type III exits for a maximum passenger seating of 215 are precluded.
    The first table of Sec. 25.807(d)(1) currently places several 
limitations on the passenger emergency exit configuration. For example, 
the table does not permit the use of Type IV exits in airplanes with 
more than 9 seats. There must be at least two pairs of exits for any 
passenger seating configuration above 19, and there must also be at 
least one pair of Type I or larger exits for passenger seating 
capacities of 40 or more. As proposed in Notice 90-4, these and other 
limitations concerning the type and number of exits required for 
specific passenger seating configurations would be retained. The 
existing requirement that there must be at least one pair of Type I or 
larger exits in each side of the fuselage for passenger seating 
configurations of 40 or more would be retained except that it would 
apply to passenger seating configurations of 41 or more rather than 40 
or more. The existing requirement that there must be at least two Type 
I or larger exits in each side of the fuselage for passenger seating 
configurations of 110 or more would also be retained except that it 
would apply to passenger seating configurations of 111 or more.
    The FAA reviewed the results of previous evacuation demonstrations 
involving airplanes with two adjacent Type III exits on each side of 
the fuselage. From this review, it was noted that two adjacent Type III 
exits consistently fail to provide a rate of egress that is double that 
of a single Type III exit. Typically, some evacuees fail to bypass one 
exit in order for there to be a steady flow through the adjacent exit. 
The rate of egress through the exit that some evacuees must bypass is 
generally equal to that through a single similar exit, but the rate of 
egress through the second exit is consistently less. The FAA, 
therefore, proposed in Notice 90-4 that the combined passenger rating 
of two adjacent pairs of Type III exits would be limited to 65. For 
purpose of compliance with this requirement, two Type III exits 
separated by fewer than three passenger seat-rows would be considered 
to be adjacent (i.e. fewer than three seat-rows plus two passageways 
located between adjacent vertical edges of the two exits). The 
pertinent parameter is the number of seat rows; however, with typical 
row spacing this would be about 80 to 90 inches between adjacent 
vertical edges of the two exits. (Notice 90-4 quoted 90 to 100 inches; 
however, 80 to 90 inches is more likely.) It was also proposed that the 
combined passenger rating for all Type III exits would not exceed 70. 
Depending on whether the first two pairs were eligible for the full 70 
passenger rating, no or very little additional credit would be given 
for any additional pairs of Type III exits. An additional conservatism 
in Type III exits because the widths of the accesses to the Type III 
exits in the studied evacuation demonstrations were far less than that 
required today because of recent safety regulatory changes.
    Taking both the exit ratings and the specific constraints proposed 
in Sec. 25.807(g), the practical effect of the proposed changes on 
airplanes with 179 or fewer passenger seats would be as follows:
    (a) With 1 through 9 passenger seats, the table of 
Sec. 25.807(d)(1) specifies at least one Type IV exit in each side. 
That requirement would remain unchanged. The table of Sec. 25.807(d)(1) 
notwithstanding, Sec. 25.807(d)(4) currently specifies that an exit 
meeting at least the dimensions of a Type III exit must be installed in 
each side if the vertical location of the wing does not allow the 
installation of overwing exits. That requirements would be retained in 
proposed Sec. 25.807(g)(1).
    (b) With 10 through 19 passenger seats, the table of 
Sec. 25.807(d)(1) specifies at least one Type III exit in each side. 
That requirement would remain unchanged.
    (c) With 20 through 39 passenger seats, the first table of 
Sec. 25.807(d)(1) specifies at least one Type II and one Type III exit 
in each side even though the combined ratings shown in the second table 
of that section would total 75 passenger seats. The combined ratings of 
proposed Sec. 25.807(g) would also total 75 passenger seats for this 
combination of passenger seats; however, the number of passenger seats 
permissible with this combination of exit types would be limited to 40 
by proposed Sec. 25.807(g)(5). That would be one more passenger seat 
than currently permitted by this combination of exit types. The margin 
of safety provided by the current rule would be maintained since 40 
passenger seats is only 53% of the combined ratings of that combination 
of exit types.
    (d) With 40 through 79 passenger seats, the table of 
Sec. 25.807(d)(1) specifies at least one Type I and one Type III exit 
in each side. As proposed, the exit combination currently specified for 
airplanes with 20 to 39 seats could also be used for one with 40 
passenger seats. As in the case described above, a number of different 
combinations of smaller exit types might provide sufficient combined 
passenger ratings for airplanes with 41 through 79 passengers; however, 
those combinations would be precluded by the constraints contained in 
proposed Sec. 25.807(g). Proposed Sec. 25.807(g)(5) would specify that, 
for more than 40 seats, there must be at least two exits in each side 
and that one of those must be at least a Type I exit. That would 
preclude for example, an alternative configuration of one smaller Type 
II exit and two Type III exits in each side even though the combined 
passenger ratings show in proposed Sec. 25.807(g) for that combination 
of exits would total 105 or 110 passenger seats. It would also preclude 
an arrangement with only one large Type A or Type B exit in each side 
in lieu of the Type I and Type III exits. As proposed, the combination 
of exit types currently specified for airplanes with 41 through 79 
passenger seats could also be used for an airplane with 80 passenger 
seats.
    (e) With 80 through 109 passenger seats, the table of 
Sec. 25.807(d)(1) specifies at least one Type I and two Type III exits 
in each side. As proposed, the combination of exit types for airplanes 
with 40 through 79 passenger seats could also be used for those with 80 
passenger seats. Although the specific constraints of proposed 
Sec. 25.807(g) would preclude certain undesirable combinations of exit 
types, the proposed changes would allow a degree of flexibility in the 
81 through 109 passenger seat range. For example, two of the newly 
proposed Type C exits could be used in lieu of one Type I and two III 
exits. Also, two Type I exits could be used in lieu of one Type I and 
two Type III exits provided the number of passenger seats did not 
exceed 90. As proposed, the combination of exit types currently 
specified for 80 through 109 seats could also be used for airplanes 
with up to 110 passenger seats; or 115 passenger seats if the Type III 
exits were separated sufficiently to enhance their effectiveness.
    (f) With 110 through 139 seats, the table of Sec. 25.807(d)(1) 
specifies at least two Type I exits and one Type III exit in each side. 
As proposed, the combination of exits currently specified for airplanes 
with 80 through 109 passenger seats, could be used for those with 110 
passenger seats. The combined passenger ratings of proposed 
Sec. 25.807(g) would limit the exit combination currently specified for 
110 through 139 passenger seats to 125

[[Page 57949]]

seats. Proposed Sec. 25.807(g)(6) would specify that, for more than 110 
seats, there must be at least two Type I or larger exits in each side. 
For airplanes with 111 through 125 there would be considerable 
additional flexibility in the combination of exit types used; however, 
the specific constraints of Sec. 25.807(g) would preclude certain 
undesirable combinations of exit types. For example, proposed 
Sec. 25.807(g)(6) would require the emergency exits of airplanes with 
more than 110 passengers to include at least two Type I exits in each 
side. For airplanes with more than 125 passenger seats, there would 
have to be more or larger exit types than those currently required for 
airplanes with 110 through 139 passenger seats. The choice of 
additional or larger exit types would, of course, be subject to the 
combined passenger ratings and specific constraints of proposed 
Sec. 25.807(g).
    (g) With 140 through 179 passenger seats, the table of 
Sec. 25.807(d)(1) specifies at least two Type I exits and two Type III 
exits in each side. The combined passenger rating of proposed 
Sec. 25.807(g) would limit this exit combination to 160 seats. Proposed 
Sec. 25.807(g)(7) would further limit this exit combination to 155 
seats if the Type III exits were not separated sufficiently to enhance 
their effectiveness. Proposed Sec. 25.807(g)(6) would specify that 
there must be at least two Type I exits or larger in each side. That 
would preclude an alternative configuration in which no exits are 
larger than Type II. It would also preclude a combination of exits 
involving only one exit larger than Type I and several smaller Type III 
exits in each side. For airplanes with more than 160 passenger seats, 
larger or additional exits would have to be provided. The choice of 
additional or larger exit types would be subject to the combined 
passenger ratings and specific constraints of proposed Sec. 25.807(g); 
however, this range of passenger seats would be afforded the greatest 
flexibility in the choice of exit type combinations.
    In summary, the number of passenger seats permissible with one pair 
of Type II and one pair to Type III exits would be increased from 39 to 
40. Similarly, the number permissible with one pair of Type I and one 
pair of Type III exits would be increased from 79 to 80. The increase 
would be negligible in either case insofar as the egress capability of 
the exits is concerned; however, it would be more than compensated for 
by the proposed improvement in escape slide deployment time in any 
event. The number permissible with one pair of Type I exits and two 
pairs of Type III exits would be increased from 109 to either 110 or 
115, depending on the proximity of the Type III exits. Those increases 
would also be negligible insofar as the egress capability of the exits 
is concerned, but they too would be more than compensated by the 
proposed improvement in escape slide deployment time. With two pairs of 
Type I exits and one pair of Type III exits, the permissible number 
would be significantly decreased from 139 to 125; with two pairs of 
Type I exits and two pairs of Type III exits, it would be significantly 
decreased from 179 to either 155 or 160, again depending on the 
proximity of the Type III exits. The permissible number of passenger 
seats would remain unchanged for other exit combinations. As stated 
above in the preamble, these new maximum passenger capacities are 
calculated by summing the number of passengers rated for the specific 
types of exit pairs; these ratings are identical to those in the former 
Sec. 25.807(d)(1) for increases in seating configurations beyond 179.
    As noted above, Sec. 25.807(d)(2) currently specifies that each 
exit must be a Type A or Type I exit for passenger seating capacities 
over 299. That limitation was introduced, along with the definition of 
Type A exits, with Amendment 25-15 (32 FR 13255, September 20, 1967), 
when the first wide-body airplanes were being proposed. Because those 
airplanes were to have twin aisles, the large Type A exits were adopted 
to permit simultaneous side-by-side egress of passengers from both 
aisles. Although there was no operational experience at that time with 
such airplanes, it was considered that they should not have a large 
number of small exits. The requirement that all exits be Type A or Type 
I was intended to discourage interior arrangements with numerous Type 
III exits and fewer large exits. Subsequently, the Boeing Model 767 and 
certain configurations of the Airbus Model A310 were both approved with 
one or two pairs of Type III exits under the equivalent level of safety 
provisions of Sec. 21.21(b)(1). Evacuation demonstrations and actual 
evacuations under emergency conditions with those airplanes have shown 
that a limited number of Type III overwing exits can be effective in 
twin-aisle airplanes. The FAA, therefore, proposed in Notice 90-4 to 
permit limited use of Type III exits in airplanes with passenger 
seating capacities greater than 299. Subsequent to Notice 90-4, 
Sec. 25.807(d)(5) was adopted with Amendment 25-72 to permit an 
alternate emergency exit configuration provided the overall evacuation 
capability is shown to be equal or greater than that specified. As a 
result, the proposed change is no longer substantive.
    To ensure that adequate evacuation capability is maintained if a 
primary exit becomes unusable, the FAA proposed in Notice 90-4 that at 
least two pairs of the larger exits (Type A or, as described below, 
Type B or Type C) would have to be installed to receive full passenger 
seating credit for those exits. If only one pair of Type A, B, or C 
exits were installed, the exits would be considered to be Type I exits 
and credited accordingly.
    In order to provide greater flexibility in passenger emergency exit 
design, two new exit types, Type B and Type C, were proposed in Notice 
90-4. Both types would be larger than Type I exits but smaller than 
Type A exits. They would be similar to exits that have been previously 
approved by exemption or under the equivalent level of safety 
provisions of Sec. 21.21(b)(1).
    The proposed Type B exits would be required to meet the same 
criteria as those for Type A exits except that their minimum width 
would be 32 inches in lieu of 42 inches, and the maximum allowable 
corner radii would be six inches in lieu of seven inches. Like Type A 
exits, Type B exits would have to have passageways at least 36 inches 
wide leading from each main aisle and be equipped with dual-lane escape 
slides. Based on the egress rate demonstrated by the petitioner, 
Exemption No. 1573 was granted to permit a passenger rating of 80 for a 
pair of these exits in the McDonnell Douglas Model DC-10. Similar exit 
pairs installed later in one configuration of the Boeing Model 757 were 
given a passenger rating of 75 based on the egress rate demonstrated at 
that time. That installation was approved under the equivalent safety 
provisions of Sec. 21.21(b)(1).
    The passenger flow to, through and from the proposed Type B exits 
is similar to that through the wider Type A exits except that the two 
parallel lines of evacuees typically twist their shoulders a few 
degrees for the moment in which they are passing through the exit side-
by-side. The proposed passenger rating of Type B exits would be 68% 
that of the larger Type A exits. In essence, the difference between the 
proposed passenger rating of Type B exits and that of Type A exits 
reflects this momentary partial merging of the two parallel lines of 
evacuees as they pass through Type B exits.
    In a report entitled Study of FAR 25.807(c) Emergency Exits dated 
May 1975, the FAA Civil Aeromedical Institute (CAMI) recommended adding

[[Page 57950]]

several exit sizes to the regulations, including two that correspond to 
the proposed Type B and C exits.
    Based on a series of passenger evacuation rate tests conducted with 
exit widths of 26 to 42 inches, CAMI recommended a passenger rating of 
80 for an exit that is 32 inches wide and equipped with a dual-lane 
escape slide. Because of the differences in motor skills and reaction 
to situations typically exhibited in testing involving people, there is 
some variation in the data presented in the CAMI report concerning 
evacuation rate versus exit size.
    Considering the variation in the CAMI test data and the data in 
which approvals of the DC-10 and Boeing Model 757 doors were based, a 
passenger rating of 75 was proposed in Notice 90-4 for Type B exits. 
This would ensure that the passenger rating is appropriate for all such 
exits regardless of the size of the airplane in which they are 
installed or minor differences among the exits of different airplane 
models.
    The CAMI testing showed that other exits, similar to Type I exits 
but with additional width, provide greater passenger egress rates than 
those with the minimum width of 24 inches. CAMI, therefore, recommended 
that exit pairs at least 30 inches wide should have a passenger rating 
of 50--five greater than that for Type I exit pairs with the minimum 
width of 24 inches. Their recommendation was based on the time of 20 
seconds currently allowed for door opening and erection of the assist 
means. The exits defined as Type C in Notice 90-4 evolved from these 
CAMI recommendations.
    The FAA previously proposed to increase the minimum height of Type 
I exits to 60 inches; however, as discussed in the preamble to 
Amendment 25-15 (32 FR 13255, September 20, 1967), the proposal was 
withdrawn in light of test data showing that the greater height would 
provide no material improvement in passenger egress rate. This finding 
was corroborated by later CAMI testing.
    As proposed in Notice 90-4, Type C exits would be similar to the 
existing Type I exits, except that their minimum width, would be 30 
inches in lieu of 24 inches. In light of the earlier test results, no 
increase in minimum height was proposed for Type C exits. In addition, 
Type C exits would be required to have assist means regardless of how 
high they are above the ground. (Exits of this size without assist 
means would be considered Type I exits even though they meet the 
dimensional requirements for Type C exits.) The maximum time allowed 
for door opening and erection of the assist means (exit preparation 
time) would be reduced from 20 seconds to 10 seconds. In addition, the 
10-second exit preparation time would have to be demonstrated for non-
overwing exits in each of the attitudes corresponding to collapse of 
one or more legs of the landing gear. Such exits would not be required 
to have power-assisted means for opening in an emergency, nor 
automatically deployed slides; however, they would have to be so-
equipped, as a matter or practicality, in order to comply with the 
proposed 10-second preparation time. Nevertheless, such features would 
not be required, nor needed, if the door could be opened and the assist 
means erected within 10 seconds without them.
    In order to arrive at the passenger rating proposed in Notice 90-4, 
experience with similar exits was considered. Exemption No. 3639, which 
was granted for the British Aerospace Model BAe.146, allows a maximum 
passenger seating capacity of 109 with two exit pairs, or a passenger 
rating of 54.5 per exit pair. These exits are all 30.5 inches wide, and 
those on the left side are 58 inches high. Due to considerations other 
than emergency egress, those on the left side are 72 inches high. They 
are equipped with assist means in the form of automatically deployed, 
inflatable, self-supporting escape slides.
    In another configuration, the Boeing Model 757 was approved for as 
many as 219 passenger seats, with four exits on each side of the 
airplane, or approximately 55 passenger seats per exit. Three of the 
four exits on each side are similar to the proposed Type C exits. Exits 
Nos. 1, 2, and 4 are over 30 inches in width and have power assist 
means for opening in an emergency. It was demonstrated during full-
scale demonstrations that these exits could be opened and ready to 
accept evacuees in approximately 8.2 seconds. The No. 3 exit is less 
than 30 inches in width; however it does exceed the minimum width for a 
Type I exit. That exit was demonstrated to be usable within 12 seconds.
    In view of the testing conducted by CAMI and the consistency of 
those test results with the approvals of British Aerospace BAe.146 and 
Boeing 757 airplanes, a passenger rating of 55 was proposed in Notice 
90-4 for Type C exits.
    A number of conforming changes to other sections were also proposed 
to include references to Types B and C exits as well as the existing 
types.
    The FAA also proposed in Notice 90-4 to make extensive non-
substantive changes to enhance the clarity of those sections involved 
with emergency exits. In light of the changes already adopted by 
Amendment 25-72, some are no longer relevant; those remaining would not 
impose any additional burden on any persons.

Escape Slide Deployment

    The FAA proposed in Notice 90-4 to revise Sec. 25.809 to require 
that the assist means at all Type C exits must be erected within 10 
seconds from the time the exit opening means is actuated. The FAA also 
proposed to reduce the maximum permissible erection times for the 
assist means serving other exit types. For non over-wing exits, the 
assist means would have to be fully erected within 6 seconds. This 
would reduce the time available to prepare the escape system to accept 
evacuees in any emergency by 4 seconds. For off-wing assist means, the 
FAA proposed that they must be fully erected within 10 seconds. This 
would be consistent with the interval currently specified in TSO C69b. 
As noted above, these erection times are in addition to the interval 
permitted by Sec. 25.809(b)(2) for exit opening.

Discussion of Comments Received in Response to Notice 90-4

    Fourteen commenters responded to the invitation in Notice 90-4--
five foreign airworthiness authorities; five airplane or equipment 
manufacturers, or organizations representing such manufacturers; two 
airline employee unions; an international airline organization; and an 
individual.
    Two foreign airworthiness authorities support the proposed 
rulemaking without further comment.
    The individual commenter recommends that no passenger seat be 
installed adjacent to an overwing exit. (By ``overwing exit,'' the 
commenter is undoubtedly referring to a Type III exit since 
unobstructed passageways were already required for Type II and larger 
exits at the time the comment was made.) The recommendation is 
unrelated to the rulemaking proposed in Notice 90-4; however, the 
subject was fully addressed by recently adopted Amendments 25-76, 121-
228 and 135-43 (57 FR 19220, May 4, 1992) which specify unobstructed 
passageways leading to Type III exits.
    Some commenters suggest that any rulemaking resulting from Notice 
90-4 should be deferred to the Aviation Rulemaking Advisory Committee 
(ARAC). The ARAC is a committee of safety experts chartered by the FAA 
on

[[Page 57951]]

February 5, 1991, to develop future proposed safety standards by using 
a systems-type analysis. Although much of the future proposed 
rulemaking of this nature will be developed by ARAC, it is not 
considered appropriate to defer this particular subject to ARAC since 
the proposed rulemaking has already been developed and published for 
public comments.
    The international airline organization forwarded comments from two 
foreign airlines. One airline supports the proposed rulemaking, stating 
that it clarifies the existing rules and has the potential for 
increased flexibility in aircraft design. The other airline has 
reservations concerning the proposed slide erection times but supports 
the other aspects of the proposed rulemaking. The latter airline did 
not elaborate on its reservations.
    Three commenters support the proposed change concerning assist 
space in the apparent belief that it introduced a new requirement for 
assist space at exits other than Type A exits. Actually, all exits 
other than Type A are already required to have such assist space if 
they are required by Sec. 25.810(a) to have assist means. The only 
change proposed in this regard was simply a conforming change to add 
consideration of Type B emergency exits. The recent consolidation of 
all assist space requirements in Sec. 25.813(b) should preclude further 
confusion in that regard.
    The three commenters also propose that the dimensions of the 
required assist space should be defined more precisely. Any change of 
that nature would be beyond the scope of Notice 90-4 and could not be 
considered at this time; nevertheless, it is being considered for 
future rulemaking.

Type and Number of Emergency Exits

    One commenter believes the passenger ratings of all exit types 
should be reconsidered. According to the commenter, the ratings are 
based on obsolete assumptions and are not verified with data from 
actual evacuations. In particular, the commenter notes that the egress 
rate of an exit is dependent on the presence and type of assist means. 
In the same vein, another commenter believes that additional credit 
should be given for exits not requiring assist means. In light of the 
successful evacuations that have been accomplished under actual 
emergency conditions, the FAA does not concur that the present 
passenger ratings of all exit types are inappropriate as suggested by 
the first commenter. The FAA does, however, concur that the egress rate 
of an exit type may be dependent on the presence and type of assist 
means. Although not specifically stated by either commenter, the egress 
rate for exit types not requiring assist means is undoubtedly dependent 
also on the distance from the exit sill to the ground. Nevertheless, 
any changes beyond those proposed in Notice 90-4 would have to be 
deferred for future rulemaking. It must be recognized that extensive 
additional testing would have to be conducted before any changes of 
this nature could be proposed.
    The commenter also suggests that credit should be given for 
unpaired exits because, according to the commenter, it is quite rare 
that one side of the airplane is blocked by fire, and usable exits are 
distributed in a less predictable manner over both sides and the length 
of the airplane. The FAA does not consider any change in that regard to 
be appropriate. The unpredictability of fire or other circumstance that 
might render an exit unavailable is the very reason why credit can not 
be given for an exit that does not have a counterpart on the opposite 
side of the airplane. Whether one complete side would be likely to be 
blocked by fire is not relevant. It is necessary to have a 
corresponding exit on the opposite side if only one exit is blocked. 
Contrary to the first commenter's assertion, there have been many 
instances in which an exit on one side was blocked by fire while its 
counterpart on the opposite side was clear and usable. The commenter 
also implies that exits should be distributed over the length of the 
airplane. It is recognized that there is a practical limit to the 
lengthwise distribution of exits in smaller airplanes; however, exits 
are already required to be distributed along the length of the cabin, 
as well as on either side, to the greatest extent practicable. In 
regard to the second comment, part 25 does not require the number of 
exits on both sides to be equal. Due to practical considerations, such 
as normal passenger entry, service access, etc., the designer may 
choose to install more openings in one side than the other; however, 
any opening that does not have a counterpart on the other side is not 
credited as an emergency exit.
    Section 25.807(f)(2) presently states that, unless another location 
affords a more effective means of passenger evacuation or the airplane 
has a ventral or tail cone exit, an airplane is only required to have 
one pair of floor-level exits must have that exit pair located in the 
rearward part of the passenger compartment. The commenter believes that 
Sec. 25.807(f)(2) should be removed or amended to emphasize locating 
the sole pair of floor-level exits in the forward part of the passenger 
cabin. The FAA concurs that there are some circumstances in which that 
would be preferable, but not that the forward end of the cabin is a 
preferable location in general. Several factors must be considered for 
any particular design, including proximity of the propeller plane, 
engine inlet or engine exhaust, potential sources of fires, potential 
fuselage impact damage, etc. Another consideration is that the flight 
attendant must be stationed near those exits to direct the evacuation. 
Having the exit pair, and the associated flight attendant, at the rear 
of the cabin is advantageous in situations where the flightcrew can 
assist the flight attendant by directing the evacuation from the 
forward end of the cabin. The FAA does not concur that the commenter's 
proposed change is appropriate since the rule already permits locating 
the exits at the forward end of the cabin when that location would, in 
fact, afford a more effective means of evacuation. Furthermore, it is 
arguable whether the forward end is predominantly the preferable 
location, as the commenter believes. In any event, a change of this 
nature would be beyond the scope of Notice 90-4 and could not be 
adopted at this time even if it were deemed to have merit.
    The same commenter asserts that ventral and tail-cone exits have 
not contributed to the rapid evacuation of occupants from airplanes 
during life-threatening situations and questions whether they should 
remain in part 25 as creditable emergency exits. Contrary to the 
commenter's assertion, service experience has shown that ventral and 
tail-cone emergency exits can provide valuable means of emergency 
egress and should remain as creditable exits.
    The commenter further questions whether the current passenger 
ratings for those exits are appropriate. Another commenter recommends 
that the passenger rating of ventral emergency exits should be reduced 
by 50%. That commenter assets the ventral exit would probably be usable 
only half the time because of possible landing gear failure. This too 
would go beyond the scope of the notice; however, it must be noted that 
a change of this nature would be based on flawed logic. The percentage 
of emergency evacuations in which an exit is usable has no bearing on 
how many persons can safely pass through it when it is usable. 
Nevertheless, the commenter's apparent concern is already addressed by 
current Sec. 25.807(d)(3). That section, which now becomes 
Sec. 25.807(g)(9), specifies that a ventral exit must provide the same 
rate of egress as a Type III exit with the airplane in the most adverse 
exit

[[Page 57952]]

opening condition that would result from the collapse of one or more 
landing gear legs. If the geometry of the airplane is such that the 
exit would not provide this rate of egress with the most adverse 
landing-gear failure-condition, no credit is given for the exit.
    There is, of course, no assurance that any particular exit, 
regardless of its type and location, will be available for use in every 
accident that may occur. As noted above, the standards of part 25 are 
based on the assumption that only half of the required exits will be 
usable due to fire, crash damage or other adverse circumstance. There 
is no need evident at this time to change the passenger rating of 
either ventral or tail-cone exits, nor any basis on which to establish 
new ratings. Any future change involving either an increase or a 
decrease in the passenger ratings for those exit types would have to be 
based on considerable additional testing.
    One commenter expresses concern that the requirement of 
Sec. 25.807(c)(7) concerning the maximum distance between exits would 
be removed. (This requirement was contained in Sec. 25.807(d)(7) at the 
time Notice 90-4 was published; however, it was moved to 
Sec. 25.807(c)(7) with the adoption of Amendment 25-72.) The omission 
of this requirement from proposed Sec. 25.807 was actually inadvertent. 
There was no intention to remove this requirement, and the final rule 
has been corrected accordingly.
    Another commenter recommends that all non-floor level passenger 
emergency exits should be eliminated (i.e., Types III and IV, ventral 
and some tail cone exits) and that, in particular, Type III exits 
should not be used in airplanes with more that 299 passenger seats. The 
FAA does not concur with the commenter that they should be eliminated 
altogether. Type III exits were previously permitted in airplanes with 
as many as 299 seats; and, as discussed above, they can now be used in 
larger airplanes provided the overall evacuation capability is not 
diminished. They have proven to be effective means of egress. Due to 
structural weight and cabin space considerations, it would be 
impractical to require the use of larger exit types exclusively in lieu 
of those exits.
    As noted above, service experience has shown that ventral and tail-
cone exits can provide valuable means of emergency egress and should 
remain as creditable exits.
    As also noted above, Type IV exits are permitted in airplanes with 
nine or fewer passengers; however, Sec. 25.785(h) requires each 
passenger entry door in the side of the fuselage to qualify as a Type 
II or larger emergency exit. Although it can only be considered a Type 
IV exit when the corresponding exit on the opposite side is also at 
least a Type IV exit, the opening in one side of the fuselage of an 
airplane with nine or fewer seats is already required by Sec. 25.783(h) 
to meet the requirements of at least a Type II exit. It would be 
extremely impractical from the standpoints of structural weight and 
lost cabin space to require the exits on both sides of the cabins of 
airplanes with nine or fewer seats to be Type II or larger exits. 
Furthermore, the FAA is not aware of any service history indicating 
that these small exits are not satisfactory for the smaller transport 
category airplanes.
    The rationale given by the commenter for not permitting the use of 
Type III exits in airplanes with more than 299 passengers is that the 
floor-level exits may be unusable and that it would be necessary to 
evacuate more than 299 passengers through a Type III exit. As noted 
above, the largest passenger rating for any exit pair (Type A) is 110 
passengers. An airplane with more than 299 passengers would, therefore, 
have to have a minimum of three floor-level exit pairs in addition to 
the pair of Type III exits. As noted earlier, the standards of part 25 
are based on the assumption that half of the required exits may be 
unusable due to fire or crash damage. It is unrealistic to believe that 
not half, but all six floor-level exits would be rendered unusable in 
an otherwise survivable crash, as the commenter suggests, leaving only 
a pair of Type III exits usable. As noted above, the original concern 
was not the use of Type III exits in the larger airplanes per se; it 
was actually whether they would be effective in airplanes with twin 
aisles. As also noted above, experience with Airbus Model A310 and 
Boeing Model 767 airplanes has shown that Type III exits can be 
effective in twin-aisle airplanes. (Another commenter states that those 
exits in the Airbus Model A310 are derated Type I exits rather than 
Type III exits. Actually the exits provided at the same location in 
some A310 airplanes are fully qualified as Type I exits. Those provided 
at that location in other A310 airplanes can only be considered Type 
III by definition since they fail to meet all of the qualifications of 
a larger exit type. In any event, the experience gained with those 
exits is pertinent regardless of how they are identified.)
    The commenter supports the establishment of the new Type B exit, 
but questions whether it is effective enough to support the proposed 
passenger rating of 75. The commenter expresses concern that the exit 
may cause a bottleneck in passenger flow, since it could be four inches 
narrower than the passageway leading to it, and suggests that the 
passengers rating should be reduced from 75 to 65. Another commenter 
believes that the difference would cause a bottleneck but, instead of 
recommending that the passenger rating be reduced, suggests that the 
width of the passageway should be reduced to 30 inches.
    As noted above, the effectiveness of Type B exits has already been 
demonstrated with such passageways to support passenger ratings of 80 
and 75 for Douglas DC-10's and Boeing 757's, respectively; and the more 
conservative passenger rating of the two was selected for the proposed 
rule. As shown by previous tests, the effectiveness of a Type B exit is 
maintained by having two uniform parallel lines of evacuees leading to 
the exit. Although the exit is not as wide as a Type A exit, the two 
parallel lines merge at the exit only to the limited extend needed to 
pass through the exit before continuing as two parallel lines down the 
assist means (i.e. the inflatable slide). Typically, the evacuees twist 
their shoulders a few degrees for the moment in which they are passing 
through the exit side-by-side. The delay due to this momentary merging 
is reflected in the proposed passenger rating of 75-68% of that of Type 
A exits. There is no basis to support arbitrarily reducing it further 
to 65.
    Contrary to the second commenter's assertion, reducing the width of 
the passageway to less than 36 inches would actually be 
counterproductive. The evacuees could not be expected to maintain two 
uniform parallel lines in a narrow passageway if doing so would 
necessitate keeping their shoulders twisted for the entire length of 
the passageway. The use of a narrower passageway would, therefore, 
disrupt the orderly flow of parallel lines of evacuees to the exit and 
result in greatly reduced flow through it.
    One commenter believes that an additional exit type should be 
defined. The proposed additional type would be similar to proposed Type 
B exits except for the use of a single-lane slide. In the absence of 
additional test data showing otherwise, it appears that an exit of this 
nature might provide egress capability no greater than that of the 
proposed Type C exit. In any event, defining this or any other 
additional exit type would be beyond the scope of Notice 90-4 and could 
not be implemented at this time.
    A commenter requests that the capacity of a Type B exit be 
demonstrated by any air carrier

[[Page 57953]]

requesting an increase in the number of passenger seats. Compliance 
with the emergency evacuation requirements of Sec. 25.803 is already 
required for any increase in maximum seating capacity over that 
previously shown satisfactory in accordance with that section.
    One commenter notes that the proposed maximum corner radii of six 
inches is inconsistent with the corresponding requirements for other 
exit types that are functions of the exit width. The commenter further 
questions whether the maximum corner radii for other exit types is 
based on the actual width of the exit or on the minimum required width 
for that particular exit type. The commenter then raises the 
possibility that the standards should be expressed in terms of minimum 
sill width, i.e. door width less the corner radii.
    In answer to the commenter's question, the corner radii currently 
specified for other exit types are based on the minimum required width 
rather than the actual width of the exit. The FAA recognizes that the 
current presentation could be misinterpreted in that regard and concurs 
that expressing the maximum corner radii in absolute dimensions is 
preferable. Although the pertinent parameters are actually the sill 
width, as the commenter suggests, and corresponding dimension at the 
top of the exit, it appears that requirements expressed in those terms 
could easily be misinterpreted, particularly if the door is a 
nonstandard oval or trapezoidal shape. After carefully considering the 
three methods of presentation, the FAA has concluded that expressing 
the requirement in terms of actual corner radii is preferable because 
it is least likely to be misinterpreted. Accordingly, Sec. 25.807(a) is 
amended to specify maximum corner radii of 8 inches for Type I exits, 7 
inches for Type II, Type III and Type A exits, and 6.3 inches for Type 
IV exits. For the same reason, Sec. 25.807(g)(9)(ii) specifies corner 
radii of 7 inches for tail cone exits. The maximum corner radii for 
Type B exits is 6 inches as proposed and 10 inches for Type C exits. 
There changes are nonsubstantive because they simply state the same 
values in a way less likely to be misinterpreted.
     The same commenter asserts that maximum corner radii based on the 
minimum exit width are not consistent with structural design principles 
(i.e. corner radii should be increased for large cutouts in order to 
reduce the stress levels). It must be emphasized that the dimensions 
specified in Sec. 25.807 describe the minimum openings. As stated in 
Sec. 25.807(d)(5), openings larger than those specified, whether or not 
of rectangular shape, may be used if the specified rectangular opening 
can be inscribed within the actual opening. The designer can, 
therefore, increase corner radii as much as needed for structural or 
other considerations simply by increasing the overall size of the exit 
opening sufficiently to allow an opening with the specified length, 
width and corner radii to be inscribed within the actual opening.
    One commenter asserts that the testing conducted by CAMI to support 
the passenger rating of proposed Type C exit pairs is invalid because a 
dual lane slide was used. As discussed above, Type B exits are wide 
enough for the two parallel lines of evacuees to partially merge 
momentarily while passing through the exit, then continue down the 
assist means in two parallel lines. Type C exits, on the other hand, 
are not wide enough for evacuees to form two parallel lines after 
passing through the exit. No matter how wide the slide is, evacuees 
continue down the slide in one single file. The width of the assist 
means, i.e. the slide, used in the CAMI testing of Type C exits is, 
therefore, irrelevant.
    Three commenters do not believe there is justification for 
requiring Type C exits to have assist means regardless of how close 
they are to the ground. All of the data presently available to support 
the passenger rating for Type C exit pairs are based on tests conducted 
with assist means. In the absence of additional test data showing 
otherwise, it appears that exits of the dimensions of proposed Type C 
exits without assist means would not perform any better than Type I 
exits. In any event, defining exits of those dimensions without assist 
means would be beyond the scope of Notice 90-4 and could not be 
undertaken at this time. Designers would be free to install exits of 
those dimensions without assist means; however, the exits would be 
considered Type I exits and credited accordingly.
    Another commenter supports the development of the Type C exit, but 
recommends that the passenger rating be reduced from 55, as proposed, 
to 50. The commenter bases this recommendation on the assertion that 
more than half of the emergency exits would probably be unavailable in 
an actual emergency. As noted earlier, the standards in part 25, and 
those proposed in Notice No. 90-4, are based on the assumption that 
half of the exits are unusable due to fire, structural damage or other 
adverse circumstance. The validity of the commenter's assertion that 
more than half would be unusable has not been established: however, it 
would be an issue common to all emergency exit types. There is, 
therefore, no reason to single out Type C exits and to arbitrarily 
reduce the rating of those exits. Any change based on the assertion 
that more than half of the exits would be unavailable would be beyond 
the scope of Notice 90-4 and could not be adopted at this time.
    The commenter also makes a number of recommendations in other areas 
that are beyond the scope of this rulemaking, such as minimizing 
jamming of exits, dispatch with inoperative doors, optimal width of 
passageways to exits and assist space for flight attendants. The 
commenter's recommendation concerning width of passageways leading to 
exits was addressed, in part, by recently adopted Amendments 25-76, 
121-228 and 135-43 (57 FR 19220, May 4, 1992). Any other 
recommendations, if found to have merit, would have to be the subject 
of future rulemaking.
    One commenter believes that the passenger ratings should be 
increased for several combinations of Type I, Type II and Type III 
exits. The commenter cites consistency with the rest of the proposed 
changes in passenger ratings, apparently in the belief that any exit 
type should be given the highest passenger rating previously permitted 
for that type under any circumstances or with any combination of other 
exit types. The FAA does not concur. The fact that ratings would be 
changed to remove inconsistencies does not imply that the 
inconsistencies must be resolved by simply granting the highest rating 
previously given for an exit type under any circumstance. By the same 
token, this does not imply that the inconsistencies must be resolved by 
arbitrarily granting the lowest rating previously given, as other 
commenters seem to believe.
    In order to resolve the inconsistencies, preference was generally 
given to the more reliable passenger ratings contained in the second 
table of Sec. 25.807(d)(1). Where substituting the passenger ratings of 
the second table would have resulted in significant increases for 
certain combinations of exit types shown in the first table, specific 
constraints on their use were proposed in Sec. 25.807(g). As a result, 
there was no significant increase in any instance, an insignificant 
increase of one passenger seat in three instances, and significant 
decreases of 14 and 24 seats in two others. As noted above, the 
increase of one seat would be negligible insofar as the egress 
capability of the exits is concerned; however, it would be more than 
compensated for by the proposed

[[Page 57954]]

improvement in escape slide deployment time in any event. Although most 
transport category airplanes are required to have escape slides, some 
have exits located close enough to the ground that slides are not 
needed. For those, even more time would be afforded for egress since no 
time would be needed for slide deployment. No supporting data were 
presented to justify either greater or lower passenger ratings; 
therefore, the various exit types are rated as proposed.
    Two commenters support the proposed reduction in passenger ratings 
of closely located Type III exits in proposed Sec. 25.807(g)(7). 
Another commenter opposes the proposed reduction and believes that the 
primary considerations are integrity of the access and optimized 
opening mechanism and hatch weight. The FAA concurs that those are both 
important considerations; however, they are not relevant to the 
proposal. As noted above, actual demonstrations show that the rate of 
egress through one exit is consistently less because some evacuees must 
bypass the first exit they reach to use that exit.
    A third commeter does not support the proposed reduction in 
passenger ratings of closely located Type III exits because, according 
to the commenter, extensive full scale evacuation tests have justified 
the 70 passenger rating of Type III exits regardless of their spacing 
and the exit flow is determined by the exit opening rather than the 
aisle flow rate. Again, the comments are not relevant to the proposal. 
The issue is not whether the aisle is capable of feeding enough 
evacuees to maintain maximum flow nor whether the rating for Type III 
exits in general is justified. Instead, the proposed reduction 
recognizes that some persons, who must bypass the first exit they reach 
and egress through the other exit for maximum total flow to occur, 
choose to join the line of evacuees waiting to use the first exit. 
Spacing exits farther apart and having more passengers seated between 
them reduces or eliminate altogether the number of passengers who must 
bypass an exit for maximum total flow.
    One commenter believes that the criteria for reduction in the 
ratings should be 84 inches between exit centerlines rather than three 
passenger seat rows, based on an assumed minimum seat row pitch of 28 
inches. As noted above, three passenger seat rows would typically 
result in approximately 80 to 90 inches between adjacent vertical edges 
of the two exits, or 100 or 120 inches between exit centerlines. 
Regardless of the value chosen, the FAA does not concur because the 
pertinent parameter is not the measured distance between the exits, per 
se, but the number of rows (i.e., the number of passengers) located 
between the exits. The comment does, however, raise the possibility 
that the phrase `` * * * two Type III exits located within three 
passenger seat rows of each other * * * '' could be misinterpreted. To 
preclude any confusion in that regard, Sec. 25.807(g)(7), as adopted, 
reads`` * * * two Type III exits that are separated by fewer than three 
passenger seat rows * * * ''
    One commenter does not concur that the combined credit for all Type 
III exits should be limited to 70 passengers, i.e., no or very limited 
credit given for more than two pairs of Type III exits. The commenter 
notes that it is possible to distribute more than two pairs of Type III 
exits in airplanes with exceptionally long wing chord, such as 
supersonic transports.
    The FAA is not aware of any previously type-certificated transport 
category airplane with more than two pairs of Type III exits. 
Generally, designers have elected to utilize Type III exits only when 
they can be located over the wing, inherently limiting airplanes to 
only two such exits because of the limited wing chord length available. 
As the commenter suggested, it is possible that there may be future 
airplanes with extremely long wing chords over which more than two 
pairs of Type III exits could be distributed. Also, it is possible to 
utilize Type III exits at non-overwing locations. Nevertheless, the use 
of more than two pairs of Type III exits would be a novel or unusual 
design feature not envisioned at the time the standards for such exits 
were developed. Based on information presently available, there are 
serious doubts as to the viability of multiple pairs of such exits in 
regard to both access within the cabin and orderly escape from them 
outside the airplane. In addition, the advisability of fewer larger 
exits in favor of having more than two pairs of Type III exits is 
questionable. In the absence of extensive additional testing, the FAA 
does not concur that the combined credit for all Type III exit pairs 
should exceed 70 passengers.
    One commenter believes that a 42 inch wide escape route is needed 
for two adjacent Type III exits only when the two exits share a common 
escape route. (This requirement was proposed as Sec. 25.803(e)(1); 
however, it would become Sec. 25.810(c)(1) due to the change in 
editorial structure that resulted from Amendment 25-72.) That was, in 
fact, the intent of the proposal; however, it appears in light of the 
comment that ``adjacent'' may result in varying interpretations. To 
preclude any confusion in this regard, Sec. 25.810(c)(1) refers to a 
common escape route from two Type III exits rather than an escape route 
from adjacent Type III exits.
    A commenter believes that there is confusion in proposed 
Sec. 25.785(h) between ``near'' and ``adjacent'' in regard to the 
proximity of flight attendant seats to Type B exits. Actually, the 
proposed rule is the same as current Sec. 25.785(h) insofar as use of 
those terms is concerned.
    Contrary to the commenter's assertion that the terms are presently 
considered interchangeable, the distinction in terminology is used 
because Type A and, as proposed, Type B exits must meet a higher 
standard than other floor-level exits. Any flight attendant seats 
provided must be located in the general vicinity of required floor-
level exits; however, there is no requirement to provide a separate 
flight attendant seat for each floor-level exit other than a Type A 
exit or, as proposed, a Type B exit. In some instances, the number of 
required floor-level exits may exceed the number of flight attendant 
seats provided; in that case, one seated flight attendant would be 
expected to serve more than one exit, e.g., exits located on opposite 
sides of the cabin. The seat provided for that flight attendant can be 
located ``near,'' i.e., in the general vicinity of, both exits, but it 
would not generally be considered to be located ``adjacent,'' or next 
to, both exits--particularly if the exits are located on opposite sides 
of the cabin. For Type A and, as proposed, Type B exits, a flight 
attendant seat must be provided for each exit and must generally be 
located next to the exit, not just in the general vicinity. The 
distinction provided by the terms ``near'' and ``adjacent'' is, 
therefore, correct.
    The same commenter note that proposed Sec. 25.807(e) would require 
exits to be distributed as uniformly as `possible,' while earlier 
language required them to be distributed as uniformly as practicable.'' 
Actually, the word ``practicable'' was replaced with ``practical'' when 
the requirement was moved to Sec. 25.813 in Amendment 25-72. The FAA 
has carefully considered the definition of each of the three terms, as 
well as the intent of the rule, and has concluded that the present term 
``practical'' is appropriate and should be retained. Advisory Circular 
25.807-1 provides guidance material concerning compliance with this 
section.
    One commenter objects to the proposed requirement that if a Type A, 
Type B or Type C exit is installed, there must be at least two Type C 
or larger exits installed in each side of the

[[Page 57955]]

fuselage. The commenter asserts that the requirements for uniformity of 
passenger exit distribution and the ``certification process'' would 
ensure that the loss of one exit would not have a critical impact on 
the evacuation capability of the airplane. As noted above, this 
requirement was proposed to ensure that adequate evacuation capability 
would be maintained in the event a primary exit became unusable. In the 
absence of this proposal, it would be possible for a 145 passenger 
airplane, for example, to be type certificated with one Type A exit and 
one Type III exit in each side of the fuselage. If one of the Type A 
exits was unusable due to fire, structural damage or other adverse 
circumstance, 38% of the total egress capability would be lost. 
Similarly, if both Type A exits were unusable, only 24% of the egress 
capability would remain. Contrary to the commenter's assertion, the 
requirements for uniformity of passenger exit distribution would not 
ensure that the loss of one exit would not have a critical impact on 
the evacuation capability of the airplane.

Escape Slide Deployment

    Several commenters object to the times specified for erection of 
the assist means serving proposed Type C exits; however, none present 
any factual data to support their apparent contention that more time 
should be permitted for erection. As discussed above, the proposed 
erection time is based on the demonstrated capability of current state-
of-the-art devices.
    One commenter supports the proposed reduction in erection times, 
but notes that essential equipment should not be relocated to the 
airplane to achieve those reductions. Since the assist means remains 
attached to the airplane, there would be no reason to require any 
essential equipment to be attached to the device insofar as it 
functions as an assist means. It appears, however, that the commenter 
is actually referring to dual-purpose inflatable devices, sometimes 
referred to as slide rafts. Slide rafts are designed to remain attached 
to the airplane and serve as assist means during an emergency 
evacuation on land, or to be detached from the airplane and serve as 
liferafts following a ditching. Section 25.1415(c) currently requires 
approved survival equipment to be attached to each liferaft, and that 
requirement would not be affected by any of the changes proposed in 
Notice 90-4.
    Some commenters also object to initiating the measurement of 
erection time when the means for opening the exit is actuated rather 
than when erection is begun, as is currently specified for other exit 
types. It is not clear whether their intent is to achieve a more 
relaxed total deployment interval by specifying that the device must be 
fully erect within 10 seconds after erection is begun, or whether they 
simply object to including exit opening in the time interval regardless 
of the total time permitted. In contrast, another commenter, a foreign 
airworthiness authority, recommends that the erection duration and 
starting time requirements for other types of exits should also be 
consistent with those proposed for new Type C exits.
    As noted above, the proposed erection time is based on current 
state-of-the-art, and the FAA does not concur that a more relaxed total 
deployment interval is justified. Including exit actuation time in the 
total deployment interval actually provides the designer more 
flexibility in achieving the desired goal. If the exit opening time is 
especially rapid, there would be more time available for erection of 
the assist device. On the contrary, if the erection time is especially 
rapid, there would be more time available for exit opening. The other 
commenter's recommendation that the erection duration and starting time 
requirements for other types of exits should be consistent with those 
proposed for Type C exits appears to have merit. Although it is beyond 
the scope of Notice 90-4, it will be considered for possible future 
rulemaking.
    One commenter, a manufacturer of inflatable assist means, questions 
what constitutes when ``deployment is begun'' and suggests the phrase 
``actuation of the inflation controls is begun'' be used instead. The 
commenter notes that the latter phrase is used in Technical Standard 
Order (TSO) C69b which contains design standards for off-wing escape 
slides.
    Generally, the two phrases are interchangeable since the assist 
means are inflatable devices. Since TSO-C69b pertains specifically to 
inflatable devices, the phrase ``actuation of the inflation controls is 
begun'' is appropriate in that document. Unlike the TSO, part 25 does 
not require the assist means to be an inflatable device. It would, 
therefore, be inappropriate to use that phrase in part 25 since the 
assist means may, in fact, not be an inflatable device. For the same 
reason, the FAA concurs with another commenter that the phrase 
``actuation of the inflation system'' in proposed Sec. 25.809(h) is 
inappropriate. This requirement, now contained in Sec. 25.810(d)(4), 
has been changed to read, ``actuation for the erection system.''

Adoption of the Final Rule

    As noted above, the editorial structure of certain portions of part 
25 was changed considerably subsequent to the publication of Notice 90-
4. Except for the substantive changes discussed above and a number of 
non-substantive changes made for conformity with part 25 as it is not 
structured, the amendments are adopted as proposed in Notice 90-4.

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 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 but because of the public 
interest is a ``significant regulatory action'' as defined in the 
Executive Order; (2) is ``significant'' as defined in DOT's Regulatory 
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

Exits

    Overall, changes to the types and number of required passenger 
emergency exits will not likely result in significant modifications to 
cabin interiors nor result in significant cost differentials, either 
positive or negative. Part 25 airplane exit configurations are variable 
and are seldom at the maximum limit in terms of passengers per exit. 
Any increases in costs would be far outweighed by the benefits of 
enhanced design flexibility, consistency in standards, and improved 
evacuation capabilities.
    The addition of Type B and Type C exits will provide manufacturers 
with increased design flexibility. Configurations with Types B and C 
exits will likely cost no more, and potentially less, than 
configurations without these exits since manufacturers will most

[[Page 57956]]

likely not utilize them unless it is cost-effective to do so.
    The revisions relating to Type I exits could increase costs in 
certain instances. The current standards allow an increase in passenger 
seating configuration ranging from 45 to 70 for each additional Type I 
exit pair, depending on airplane exit configuration and total passenger 
seating capacity. The revisions will limit the allowed increase for 
Type I exit pairs to 45 passengers for all exit configurations and 
seating capacities.
    Limiting Type I exit pairs to 45 passengers will improve safety. It 
is clear that 45 passengers can evacuate through a pair of Type I exits 
more expeditiously than can a greater number. An aircraft having two 
pairs of Type I exits and two pairs of Type III exits can have 179 
passengers under the current standards but only 155 passengers under 
the revised standards, a reduction of 13 percent. However, a 
manufacturer of a design which includes 179 passengers (with two pairs 
each of Type I and Type III exits) that desires to maintain that 
capacity could, under the revised standards, replace the two Type I 
exit pairs with Type C exit pairs (the two new Type C pairs allow 110 
passengers and the two Type III pairs another 70 for a total of 180 
passengers). Evacuation from an airplane with the modified 
configuration would be easier since the Type C exit is six inches wider 
than the Type I exit. Benefits resulting from this safety enhancement 
would easily exceed any incremental design/manufacturing costs.
    While it is difficult to estimate the number of fatalities or 
injuries that might be avoided by the revised rule, studies have shown 
that exit flow rates are proportional to exit widths within the 24 to 
42 inch range. In one study, the evacuation rate increased by one 
occupant every 12 seconds for each six inch increase in exit width 
(``Study of FAR Sec. 25.807(c) Emergency Exits,'' FAA Aeronautical 
Center, May 1975, Project Report No. 70-597-120A). In another study, 
the National Bureau of Standards (NBS) (since renamed the National 
Institute for Standards and Technology), analyzed accidents involving 
fire and fatalities that occurred between 1965 and 1982 and estimated 
the number of fatalities that could have been avoided if passengers had 
additional time to escape as a result of reduced seat cushion 
flammability (`Decision Analysis Model for Passenger-Aircraft Fire 
Safety with Application to Fire Blocking of Seats,'' National Bureau of 
Standards, March 1984, NBSTR 84-2817, DOT/FAA/CT/84-8). NBS estimated 
that of 712 fire fatalities during the period analyzed, 109 could have 
been avoided if there had been 20 additional seconds of evacuation time 
(a rate of 3 lives saved per 100 million passenger enplanements). While 
having more time to evacuate an airplane is not the same as being able 
to evacuate an airplane faster, it can nevertheless serve as a proxy 
for estimating benefits, because the end result is the same--more 
passengers can egress before fire or explosion makes egress impossible. 
Reduced crowding at exits and the consequent decrease in evacuation 
time resulting from the revised exit standards could potentially save 
several lives in just one accident.

Escape Slides

    The reduced time allowed for escape slide erection will provide 
faster emergency evacuation rates and potentially prevent some 
fatalities or injuries that otherwise might be sustained. The 
technology to meet the revised standard is available and will not add 
to the cost of slides. The rule changes basically update slide 
requirements to current technology. Since costs will be unaffected and 
safety enhanced, the revisions are cost beneficial.

Regulatory Flexibility Determinations

    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 FRA requires 
agencies to assess whether rules would have ``a significant economic 
impact on a substantial number of small entities,'' and in cases where 
they would, to conduct a Regulatory Flexibility Analysis. The FAA size 
threshold for a small aircraft manufacturer is 75 or fewer employees 
(per FAA Order 2100.14A, Regulatory Flexibility Criteria and Guidance). 
Since there are no manufacturers of part 25 airplanes with 75 or fewer 
employees, the rule will not have ``a significant economic impact on a 
substantial number of small entities.''

International Trade Impact Assessment

    The rule will have no effect on the sale of U.S. airplanes in 
foreign markets or the sale of foreign airplanes in the U.S.

Federalism Implications

    The regulations adopted 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 will not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.

Conclusion

    For the reasons given earlier in the preamble, the FAA has 
determined that this is a ``significant'' regulation as defined in 
Executive Order 12866 and is ``significant'' as defined in Department 
of Transportation Regulatory Policies and Procedures (44 FR 11034; 
February 26, 1979) because of the public interest involved. In 
addition, it is certified under the criteria of the Regulatory 
Flexibility Act that this regulation will not have a significant 
economic impact, positive or negative, on a substantial number of small 
entities.

List of Subjects in 14 CFR Part 25

    Aircraft, Aviation safety, Reporting and recordkeeping 
requirements.

Adoption of Amendment

    Accordingly, the FAA amends 14 CFR part 25 of the Federal Aviation 
Regulations (FAR), as follows:

PART 25--AIRWORTHINESS STANDARDS: TRANSPORT CATEGORY AIRPLANES

    1. The authority citation for part 25 continues to read as follows:

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

    2. By amending Sec. 25.783 by revising paragraph (h) to read as 
follows:


Sec. 25.783  Doors.

* * * * *
    (h) Each passenger entry door in the side of the fuselage must meet 
the applicable requirements of Secs. 25.807 through 25.813 for a Type 
II or larger passenger emergency exit.
* * * * *
    3. By amending Sec. 25.785 by revising paragraph (h)(1) to read as 
follows:


Sec. 25.785  Seats, berths, safety belts, and harnesses.

* * * * *
    (h) * * *
    (1) Near a required floor level emergency exit, except that another 
location is acceptable if the emergency egress of passengers would be 
enhanced with that location. A flight attendant seat must be located 
adjacent to each Type A or B emergency exit. Other flight attendant 
seats must be evenly distributed among the required floor-

[[Page 57957]]

 level emergency exits to the extent feasible.
* * * * *
    4. By amending Sec. 25.807 by revising paragraphs (a)(1) through 
(a)(4), (a)(7), and (d) through (f) and by adding paragraphs (a)(8), 
(a)(9), and (g) through (i) to read as follows:


Sec. 25.807  Emergency exits.

    (a) * * *
    (1) Type I. This type is a floor-level exit with a rectangular 
opening of not less than 24 inches wide by 48 inches high, with corner 
radii not greater than eight inches.
    (2) Type II. This type is a rectangular opening of not less than 20 
inches wide by 44 inches high, with corner radii not greater than seven 
inches. Type II exits must be floor-level exits unless located over the 
wing, in which case they must not have a step-up inside the airplane of 
more than 10 inches nor a step-down outside the airplane of more than 
17 inches.
    (3) Type III. This type is a rectangular opening of not less than 
20 inches wide by 36 inches high with corner radii not greater than 
seven inches, 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.
    (4) Type IV. This type is a rectangular opening of not less than 19 
inches wide by 26 inches high, with corner radii not greater than 6.3 
inches, 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.
* * * * *
    (7) Type A. This type is a floor-level exit with a rectangular 
opening of not less than 42 inches wide by 72 inches high, with corner 
radii not greater than seven inches.
    (8) Type B. This type is a floor-level exit with a rectangular 
opening of not less than 32 inches wide by 72 inches high, with corner 
radii not greater than six inches.
    (9) Type C. This type is a floor-level exit with a rectangular 
opening of not less than 30 inches wide by 48 inches high, with corner 
radii not greater than 10 inches.
* * * * *
    (d) Asymmetry. Exits of an exit pair need not be diametrically 
opposite each other nor of the same size; however, the number of 
passenger seats permitted under paragraph (g) of this section is based 
on the smaller of the two exits.
    (e) Uniformity. Exits must be distributed as uniformly as 
practical, taking into account passenger seat distribution.
    (f) Location. (1) Each required passenger emergency exit must be 
accessible to the passengers and located where it will afford the most 
effective means of passenger evacuation.
    (2) If only one floor-level exit per side is prescribed, and the 
airplane do not have a tail-cone or ventral emergency exit, the floor-
level exits must be in the rearward part of the passenger compartment 
unless another location affords a more effective means of passenger 
evacuation.
    (3) If more than one floor-level exit per side is prescribed, and 
the airplanes does not have a combination cargo and passenger 
configuration, at least one floor-level exit must be located in each 
side near each end of the cabin.
    (g) Type and number required. The maximum number of passenger seats 
permitted depends on the type and number of exits installed in each 
side of the fuselage. Except as further restricted in paragraphs (g)(1) 
through (g)(9) of this section, the maximum number of passenger seats 
permitted for each exit of a specific type installed in each side of 
the fuselage is as follows:

Type A                                                           110    
Type B                                                            75    
Type C                                                            55    
Type I                                                            45    
Type II                                                           40    
Type III                                                          35    
Type IV                                                            9    
                                                                        

    (1) For a passenger seating configuration of 1 to 9 seats, there 
must be at least one Type IV or larger overwing exit in each side of 
the fuselage or, if overwing exits are not provided, at least one exit 
in each side that meets the minimum dimensions of a Type III exit.
    (2) For a passenger seating configuration of more than 9 seats, 
each exit must be a Type III or larger exit.
    (3) For a passenger seating configuration of 10 to 19 seats, there 
must be at least one Type III or larger exit in each side of the 
fuselage.
    (4) For a passenger seating configuration of 20 to 40 seats, there 
must be at least two exits, one of which must be a Type II or larger 
exit, in each side of the fuselage.
    (5) For a passenger seating configuration of 41 to 110 seats, there 
must be at least two exits, one of which must be a Type I or larger 
exit, in each side of the fuselage.
    (6) For a passenger seating configuration of more than 110 seats, 
the emergency exits in each side of the fuselage must include at least 
two Type I or larger exits.
    (7) The combined maximum number of passenger seats permitted for 
all Type III exits is 70, and the combined maximum number of passenger 
seats permitted for two Type III exits in each side of the fuselage 
that are separated by fewer than three passenger seat rows in 65.
    (8) If a Type A, Type B, or Type C exit is installed, there must be 
at least two Type C or larger exits in each side of the fuselage.
    (9) If a passenger ventral of tail cone exit is installed and that 
exit provides at least the same rate of egress as a Type III exit with 
the airplane in the most adverse exit opening condition that would 
result from the collapse of one or more legs of the landing gear, an 
increase in the passenger seating configuration is permitted as 
follows:
    (i) For a ventral exit, 12 additional passenger seats.
    (ii) For a tail cone exit incorporating a floor level opening of 
not less than 20 inches wide by 60 inches high, with corner radii not 
greater than seven inches, in the pressure shell and incorporating an 
approved assist means in accordance with Sec. 25.810(a), 25 additional 
passenger seats.
    (iii) For a tail cone exit incorporating an opening in the pressure 
shell which is at least equivalent to a Type III emergency exit with 
respect to dimensions, step-up and step-down distance, and with the top 
of the opening not less than 56 inches from the passenger compartment 
floor, 15 additional passenger seats.
    (h) Excess exits. Each emergency exit in the passenger compartment 
in excess of the minimum number of required emergency exits must meet 
the applicable requirements of Sec. 25.809 through Sec. 25.812, and 
must be readily accessible.
    (i) Ditching emergency exits for passengers. Whether or not 
ditching certification is requested, ditching emergency exits must be 
provided in accordance with the following requirements, unless the 
emergency exits required by paragraph (g) of this section already meet 
them:
    (1) For airplanes that have a passenger seating configuration of 
nine or fewer seats, excluding pilot seats, one exit above the 
waterline in each side of the airplane, meeting at least the dimensions 
of a Type IV exit.
    (2) For airplanes that have a passenger seating configuration of 10 
of more seats, excluding pilot seats, one exit above the waterline in a 
side of the airplane, meeting at least the dimensions of a Type III 
exit for each unit (or part of a unit) of 35 passenger seats, but no 
less than two such exits in the passenger cabin, with one on each side 
of the airplane. The passenger seat/

[[Page 57958]]

 exit ratio may be increased through the use of larger exits, or other 
means, provided it is shown that the evacuation capability during 
ditching has been improved accordingly.
    (3) If it is impractical to locate side exits above the waterline, 
the side exits must be replaced by an equal number of readily 
accessible overhead hatches of not less than the dimensions of a Type 
III exit, except that for airplanes with a passenger configuration of 
35 or fewer seats, excluding pilot seats, the two required Type III 
side exits need be replaced by only one overhead hatch.
    5. By amending Sec. 25.810 by revising paragraphs (a) introductory 
text, (a)(1) introductory text, (a)(1)(ii), (b), (c)(1), and (d) to 
read as follows:


Sec. 25.810  Emergency egress assist means and escape routes.

    (a) Each non over-wing Type A, Type B or Type C exit, and any other 
non over-wing landplane emergency exit more than 6 feet from the ground 
with the airplane on the ground and the landing gear extended, must 
have an approved means to assist the occupants in descending to the 
ground.
    (1) The assisting means for each passenger emergency exit must be a 
self-supporting slide or equivalent; and, in the case of Type A or Type 
B exits, it must be capable of carrying simultaneously two parallel 
lines of evacuees. In addition, the assisting means must be designed to 
meet the following requirements--
* * * * *
    (ii) Except for assisting means installed at Type C exits, it must 
be automatically erected within 6 seconds after deployment is begun. 
Assisting means installed at Type C exits must be automatically erected 
within 10 seconds from the time the opening means of the exit is 
actuated.
* * * * *
    (b) Assist means from the cabin to the wing are required for each 
type A or Type B exit located above the wing and having a stepdown 
unless the exit without an assist-means can be shown to have a rate of 
passenger egress at least equal to that of the same type of non over-
wing exit. If an assist means is required, it must be automatically 
deployed and automatically erected concurrent with the opening of the 
exit. In the case of assist means installed at Type C exits, it must be 
self-supporting within 10 seconds from the time the opening means of 
the exits is actuated. For all other exit types, it must be self-
supporting 6 seconds after deployment is begun.
    (c) * * *
    (1) The escape route from each Type A or Type B passenger emergency 
exit, or any common escape route from two Type III passenger emergency 
exits, must be at least 42 inches wide; that from any other passenger 
emergency exit must be at least 24 inches wide; and
* * * * *
    (d) Means must be provided to assist evacuees to reach the ground 
for all Type C exits located over the wing and, if the place on the 
airplane structure at which the escape route required in paragraph (c) 
of this section terminates is more than 6 feet from the ground with the 
airplane on the ground and the landing gear extended, for all other 
exit types.
    (1) If the escape route is over the flap, the height of the 
terminal edge must be measured with the flap in the takeoff or landing 
position, whichever is higher from the ground.
    (2) The assisting means must be usable and self-supporting with one 
or more landing gear legs collapsed and under a 25-knot wind directed 
from the most critical angle.
    (3) The assisting means provided for each escape route leading from 
a Type A or B emergency exit must be capable of carrying simultaneously 
tow parallel lines of evacuees; and, the assisting means leading from 
any other exit type must be capable of carrying as many parallel lines 
of evacuees as there are required escape routes.
    (4) The assisting means provided for each escape route leading from 
a Type C exit must be automatically erected within 10 seconds from the 
time the opening means of the exit is actuated, and that provided for 
the escape route leading from any other exit type must be automatically 
erected within 10 seconds after actuation of the erection system.
    6. By amending Sec. 25.811 by revising the introductory texts of 
paragraphs (e)(2) and (e)(4) to read as follows:


Sec. 25.811   Emergency exit marking.

* * * * *
    (e) * * *
    (2) Each Type A, Type B, Type C or Type I passenger emergency exit 
operating handle must--
* * * * *
    (4) Each Type A, Type B, Type C, Type I, or Type II passenger 
emergency exit with a locking mechanism released by rotary motion of 
the handle must be marked--
* * * * *
    7. By amending Sec. 25.812 by revising paragraph (g)(1)(ii) to read 
as follows:


Sec. 25.812   Emergency lighting.

* * * * *
    (g) * * *
    (1) * * *
    (ii) Not less than 0.05 foot-candle (measured normal to the 
direction of incident light) along the 30 percent of the slip-resistant 
portion of the escape route required in Sec. 25.810(c) that is farthest 
from the exit for the minimum required width of the escape route; and
* * * * *
    8. By amending Sec. 25.813 by revising paragraphs (a) introductory 
text, (a)(1), and (b) to read as follows:


Sec. 25.813   Emergency exit access.

* * * * *
    (a) There must be a passageway leading from the nearest main aisle 
to each Type A, Type B, Type C, Type I, or Type II emergency exit and 
between individual passenger areas. Each passageway leading to a Type A 
or Type B exit must be unobstructed and at least 36 inches wide. 
Passageways between individual passenger areas and those leading to 
Type I, Type II, or Type C emergency exits must be unobstructed and at 
least 20 inches wide. Unless there are two or more main aisles, each 
Type A or B exit must be located so that there is passenger flow along 
the main aisle to that exit from both the forward and aft directions. 
If two or more main aisles are provided, there must be unobstructed 
cross-aisles at least 20 inches wide between main aisles. There must 
be--
    (1) A cross-aisle which leads directly to each passageway between 
the nearest main aisle and a Type A or B exit; and
* * * * *
    (b) Adequate space to allow crewmember(s) to assist in the 
evacuation of passengers must be provided as follows:
    (1) The assist space must not reduce the unobstructed width of the 
passageway below that required for the exit.
    (2) For each Type A or Type B exit, assist space must be provided 
at each side of the exit regardless of whether a means is required by 
Sec. 25.810(a) to assist passengers in descending to the ground from 
that exit.
    (3) Assist space must be provided at one side of any other type 
exit required by Sec. 25.810(a) to have a means to assist passengers in 
descending to the ground from that exit.
* * * * *
    Issued in Washington, D.C., on November 1, 1996.
David R. Hinson,
Administrator.
[FR Doc. 96-28650 Filed 11-7-96; 8:45 am]
BILLING CODE 4910-13-M