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This memorandum provides dynamic test requirements and pass/fail
criteria for side-facing seats on Transport Category Airplanes. Attached
is guidance material, in the form of draft generic issue papers,
pertaining to side-facing accommodations. Single occupancy and multiple
occupancy ("divans") installations are treated separately, since there
are separate approaches to each. These drafts can be used to develop
project-specific issue papers.

Amendment 25-64, which adopted § 25.562, provides a means of enhancing
occupant protection under more realistic conditions than had previously
existed. The requirements contained therein consist of both test
conditions and pass/fail criteria.

The dynamic test conditions, in terms of both pulse severity and types
of tests currently required, are also considered to be directly
applicable to side-facing seats. While it is true that the regulation
was written with forward- and aft-facing seats in mind, the orientation
of the seat does not change the relevant test conditions, and the rule
applies to all seats.

For pass/fail criteria, however, the orientation of the seat may be
significant. Injury criteria are currently limited to head, spine, and
femur loads. Head injury is evaluated for contact experienced by the
head against any aircraft interior installations, and the pass/fail
criterion is based on the resultant head acceleration considering all
axes of head motion. The lumbar spinal load is an axially compressive
load that is primarily evaluated during the 14g, 60° test. The femur
load is also compressive, and actually has not proved to be critical
thus far. For a side-facing seat, other injury parameters may
predominate such that evaluation of those parameters may be necessary to
provide an acceptable level of safety.

The first consideration for a side-facing seat is the isolation of one
occupant from another. That is, occupants should not rely on the impact
with other occupants to provide energy absorption; body-to-body impacts
as discussed in the attachment are considered unacceptable. The second
consideration is the retention of occupants in the seat and restraint
system. Addressing this concern may necessitate providing a means of
restraint for the lower limbs as well as the torso. Failure to limit the
forward (in the airplane's coordinate system) travel of the lower limbs
may cause the occupant to come out of the restraint system or produce
severe injuries due to the resulting position of the restraint system
and/or twisting (torsional load) of the lower lumber spinal column.

A third consideration is limiting the load in the torso in the lateral
direction, where human tolerance differs from that for the forward or
aft facing directions and other potential injury mechanisms exist. The
automotive industry has developed test procedures and occupant injury
criteria appropriate for side impact conditions. Their criteria involves
limitation of lateral pelvic accelerations, and use of the human
tolerance parameter \"Thoracic Trauma Index,\" which is defined in 49
CFR § 571.214. Use of the 49 CFR § Part 572, Subpart F, Side Impact
Dummy (SID), rather than the 49 CFR § Part 572, Subpart B, Hybrid II
dummy used in the current § 25.562, test is required to evaluate these
parameters. This is the best means available at present to assess the
injury potential of a sideward impact condition. Such an evaluation is
considered necessary to provide an acceptable level of safety for these
types of seats.

Other potential injury mechanisms appropriate for aircraft seats may
exist. However due to the lack of useful injury criteria for those other
potential injury parameters, such as neck loads and lower limb flail, we
are not able to specify criteria applicable to those areas at this time.
We believe that such criteria may be appropriate, particularly for
multiple occupancy installations, however, and intend to pursue their
further development.

For single occupancy seats, the criteria provided in the associated
attached issue paper have been determined to result in a level of safety
equivalent to that provided by the pass/fail criteria in § 25.562 for
forward or aft-facing seats. Accordingly, the certification of [single
occupancy side-facing seats]{.underline} intended to be installed to
these criteria should be documented with a [special
condition]{.underline} in accordance with the provisions and
requirements of § 21.16. We recognize that there have been approvals in
accordance with § 25.562 that may not match these criteria exactly.
While those approvals are still considered valid, any new approvals
should use as their initial position the criteria provided here. As
experienced is gained and additional data are developed, we expect that
these criteria will evolve.

For [multiple occupancy seating]{.underline}, the best criteria
currently available cannot be said to provide an equivalent level of
safety for those occupants. Therefore, the only means available for
accepting these installations would be through an
[exemption]{.underline} from the general occupant protection
requirements of § 25.785(b). In this case, the associated attached issue
paper summarizes criteria that are currently available, and could form
the basis for inclusion in a petition for exemption from the noted
requirement if an applicant so chooses. Any petition for exemption must
also, of course, address why a grant of the petition would be in the
public interest, in accordance with § 11.25(b)(5). We would like to
stress that a grant of exemption is not automatic, and the applicant
must address to the satisfaction of the FAA, why installing multiple
occupancy, side-facing seating, in lieu of forward or aft-facing seating
with a higher level of safety, is in the public interest.

We intend to continue to refine the compliance criteria for multiple
occupancy seating with the goal of establishing an equivalent level of
safety and we expect industry to assist in this effort. In the event
those criteria may be established, this memorandum will be updated
accordingly and the certification of multiple occupancy side-facing
seating may then be processed with special conditions in lieu of
exemptions. We anticipate that any designs approved under the terms of
an exemption in the interim would retain their approval, although each
exemption request will be treated individually. Any subsequent designs
would be required to comply with the criteria developed, regardless of
whether they were intended for installation on the same airplanes.

Any questions may be directed to Jeff Gardlin, telephone 425-227-2136.

Original signed by S.R. Miller for

Ronald T. Wojnar

DISTRIBUTION:

Manager, Small Airplane Directorate, ASW-100

Manager, Engine and Propeller Directorate, ANE-100

Manager, Rotorcraft Directorate, ASW-100

Manager, Aircraft Engineering Division, AIR-100

Manager, Seattle Aircraft Certification Office, ANM-100S

Manager, Los Angeles Aircraft Certification Office, ANM-100L

Manager, Anchorage Aircraft Certification Office, ACE-115N

Manager, Boston Aircraft Certification Office, ANE-150

Manager, Denver Aircraft Certification Office, ANM-100D

Manager, Atlanta Aircraft Certification Office, ACE-115A

Manager, Wichita Aircraft Certification Office, ACE-115W

Manager, Chicago Aircraft Certification Office, ACE-115C

Manager, New York Aircraft Certification Office, ANE-170

Manager, Airplane Certification Office, ASW-150

Manager, Special Certification Office, ASW-190

Manager, Brussels Certification Staff, AEU-100

> ISSUE PAPER

+-----------------------------------------+----------------------------+
|                                         |                            |
+-----------------------------------------+----------------------------+
| **PROJECT:** Generic                    | **ITEM:** CI-1             |
+-----------------------------------------+----------------------------+
|                                         | **STAGE:** 2               |
+-----------------------------------------+----------------------------+
|                                         |                            |
+-----------------------------------------+----------------------------+
| **REG. REF.:** §§ 11.25, 25.562, 25.785 | **DATE:** Nov. 12, 1997    |
+-----------------------------------------+----------------------------+
|                                         |                            |
+-----------------------------------------+----------------------------+
| **NATIONAL**                            | **ISSUE STATUS:** OPEN     |
|                                         |                            |
| **POLICY REF.:**                        |                            |
+-----------------------------------------+----------------------------+
|                                         |                            |
+-----------------------------------------+----------------------------+
| **SUBJECT:** Dynamic Test Requirements  | **BRANCH ACTION:**         |
| for Side-Facing Divans (Sofas)          | ANM-112, AAM-630, ANM-102N |
+-----------------------------------------+----------------------------+
|                                         |                            |
+-----------------------------------------+----------------------------+
| Please read [11/19/97                   | **COMPLIANCE**             |
| memo](..                                |                            |
| /../../../DOCUMENT/FINAL/SIDEFACE.DOC)\ | **TARGET:** Pre-TC         |
| Based on GIP \# C-x1                    |                            |
+-----------------------------------------+----------------------------+
|                                         |                            |
+-----------------------------------------+----------------------------+

*Petition for Exemption*

\*\*\*\*\*\*\*\*\*\*\* NOTE \*\*\*\*\*\*\*\*\*\*\*

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code references to be lost! Always use the \"Edit Variables\" selection
from the \"Edit\" Menu. This text will not print!

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**STATEMENT OF ISSUE:** Side Facing seats are considered a novel design
for Transport Category Airplanes that include amendment 25-64 in the
certification basis, and were not considered when those airworthiness
standards were promulgated. The FAA has determined that the existing
regulations do not provide adequate or appropriate safety standards for
occupants of side-facing multiple occupant seats (divans). Additionally,
the best criteria currently available for evaluation of this type of
seating do not ensure a level of safety that is equivalent to that
afforded to occupants of forward and aft facing seating. Therefore, the
only certification method available for this type of seating, for
aircraft that include Amendment 25-64 in their certification basis, is
through an exemption from the general injury requirements of 25.785(b).

This issue paper will be used to establish the minimum acceptable
testing and human injury criteria that will be applied to side-facing
divan certifications. This information will complement the exemption
process as defined in 14 CFR Part 11.25 and in no way is intended to
circumvent the need to provide an acceptable public interest argument as
required per §11.25 (b)(5).

**BACKGROUND:** Part 25 of the Federal Aviation Regulations (FAR) was
amended June 16, 1988, by Amendment 25-64, to revise the emergency
landing conditions that must be considered in the design of the
airplane. Amendment 25-64 revised the static load conditions in §
25.561, and added a new § 25.562 that required dynamic testing for all
seats approved for occupancy during takeoff and landing. The intent of
Amendment 25-64 is to provide an improved level of safety for occupants
on transport category airplanes. Because most seating is forward-facing
on transport category airplanes, the pass/fail criteria developed in
Amendment 25-64 focused primarily on these seats. Since Amendment 25-64,
several airplanes with both forward-facing and aft-facing seats have
been certificated using the criteria in Amendment 25-64, and one
airplane with single-place side-facing seats has been certificated using
equivalent criteria defined in an issue paper.

For multiple occupancy seating, the best criteria currently available
cannot be said to provide an equivalent level of safety for those
occupants. Therefore, the only vehicle available for accepting these
installations will be through an exemption from the general injury
requirements of § 25.785(b). The criteria contained in this issue paper
may be included in a petition for exemption from the noted requirement
if an applicant so chooses. Any petition for exemption must also address
why a grant of the petition would be in the public interest, in
accordance with § 11.25(b)(5), and it should be emphasized that this
public interest requirement must be satisfied regardless of the criteria
that the divan is tested to.

**FAA POSITION:** The following proposed injury criteria and
installation/testing guidelines represent the minimum acceptable
standard for incorporation in a petition for exemption from the general
occupant injury criteria of §25.785(b).

**1. The Proposed Injury Criteria**

\(a\) [Existing Criteria]{.underline}: All injury protection criteria of
§ 25.562(c)(1) through (c)(6) apply to the occupants of side facing
seating. HIC assessments are only required for head contact with the
seat and/or adjacent structures.

\(b\) [Body-to body contact]{.underline}: Contact between the head,
pelvis, or shoulder area of one Anthropomorphic

Test Dummy (ATD) on the adjacent seated ATD's is not allowed during the
tests conducted in accordance with § 25.562(b)(1) and (b)(2). Incidental
contact of the leg, feet, arms and hand that will not result in
incapacitation of the occupants is acceptable. Contact during rebound is
allowed.

\(c\) [Body-to-wall/furnishing contact]{.underline}: If the sofa is
installed aft of a structure such as an interior wall or furnishing that
may contact the pelvis, upper arm, chest, or head of an occupant seated
next to the structure, a conservative representation of the structure
and its stiffness must be included in the tests. The contact surface of
this structure must be covered with at least two inches of energy
absorbing protective foam, such as ensolite.

\(d\) [Thoracic Trauma]{.underline}: Testing with a Side Impact Dummy
(SID), as defined by 49 CFR Part 572, Subpart F, or its equivalent, must
be conducted and Thoracic Trauma Index (TTI) injury criteria acquired
with the SID must be less than 85, as defined in 49 CFR Part 572,
Subpart F. SID TTI data must be processed as defined in Federal Motor
Vehicle Safety Standard (FMVSS) Part 571.214, section S6.13.5.

\(e\) [Pelvis]{.underline}: Pelvic lateral acceleration must not exceed
130g. Pelvic acceleration data must be processed as defined in FMVSS
Part 571.214, section S6.13.5.

\(f\) [Shoulder Strap Loads]{.underline}: Where upper torso straps
(shoulder straps) are used for sofa occupants, tension loads in
individual straps must not exceed 1,750 pounds. If dual straps are used
for restraining the upper torso, the total strap tension loads must not
exceed 2,000 pounds.

**2. General Guidelines**

\(a\) All side facing seats require end closures.

\(b\) All seat positions need to be occupied for the longitudinal tests.

\(c\) For the longitudinal tests, conducted in accordance with the
conditions specified in § 25.562(b)(2), a minimum of two tests will be
required, as follows:

\(1\) One test will be required with one SID ATD in the forward most
position and Hybrid II ATD(s) in all other positions, with undeformed
floor, no yaw, and with all lateral supports (armrests/walls).

\(2\) One test will be required with one SID ATD in the center seat and
Hybrid II ATD(s) in all other positions, with deformed floor, 10 degrees
yaw, and with all lateral supports (armrests/walls). This could be
considered the structural test as well.

\(d\) For the vertical test, conducted in accordance with the conditions
specified in § 25.562(b)(1), Hybrid II ATD's will be used in all seat
positions.

**FCAA POSITION:**

Open.

**APPLICANT\'S POSITION:**

Open.

**CONCLUSION:**

Open.

> ISSUE PAPER

+-----------------------------------------+----------------------------+
|                                         |                            |
+-----------------------------------------+----------------------------+
| **PROJECT:** Generic                    | **ITEM:** CI-X             |
+-----------------------------------------+----------------------------+
|                                         | **STAGE:** 1               |
+-----------------------------------------+----------------------------+
|                                         |                            |
+-----------------------------------------+----------------------------+
| **REG. REF.:** §§21.16, 25.562, 25.785  | **DATE:** Nov. 12, 1997    |
+-----------------------------------------+----------------------------+
|                                         |                            |
+-----------------------------------------+----------------------------+
| **NATIONAL**                            | **ISSUE STATUS:** OPEN     |
|                                         |                            |
| **POLICY REF.:**                        |                            |
+-----------------------------------------+----------------------------+
|                                         |                            |
+-----------------------------------------+----------------------------+
| **SUBJECT:** Dynamic Test Requirements  | **BRANCH ACTION:**         |
| for Single Place Side-Facing Seats      | ANM-112, AAM-630, ANM-102N |
+-----------------------------------------+----------------------------+
|                                         |                            |
+-----------------------------------------+----------------------------+
| Please read [11/19/97                   | **COMPLIANCE**             |
| memo](..                                |                            |
| /../../../DOCUMENT/FINAL/SIDEFACE.DOC)\ | **TARGET:** Pre-TC         |
| Based on GIP \# C-x2                    |                            |
+-----------------------------------------+----------------------------+
|                                         |                            |
+-----------------------------------------+----------------------------+

Proposed Special Condition

\*\*\*\*\*\*\*\*\*\*\* NOTE \*\*\*\*\*\*\*\*\*\*\*

Do not revise header information above directly as this may cause field
code references to be lost! Always use the \"Edit Variables\" selection
from the \"Edit\" Menu. This text will not print!

\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*\*

**STATEMENT OF ISSUE:** Side Facing seats are considered a novel design
for Transport Category Airplanes that include amendment 25-64 in the
certification basis, and were not considered when those airworthiness
standards were promulgated. The FAA has determined that the existing
regulations do not provide adequate or appropriate safety standards for
occupants of side-facing single occupant seats (divans). In order to
provide a level of safety that is equivalent to that afforded to
occupants of forward and aft facing seating, additional airworthiness
standards, in the form of special conditions, are necessary.

This issue paper will be used to establish the minimum acceptable
testing and human injury criteria that will be applied to single
occupancy, side-facing seat certifications. This information will
complement the criteria given in § 25.562 of the Federal Aviation
Regulations (FAR), and can be used in developing Special Conditions in
accordance with § 21.16 of the FAR.

**BACKGROUND:** Part 25 of the FAR was amended June 16, 1988, by
Amendment 25-64, to revise the emergency landing conditions that must be
considered in the design of the airplane. Amendment. 25-64 revised the
static load conditions in § 25.561, and added a new § 25.562 that
required dynamic testing for all seats approved for occupancy during
takeoff and landing. The intent of Amendment 25-64 is to provide an
improved level of safety for occupants on transport category airplanes.
Because most seating is forward-facing on transport category airplanes,
the pass/fail criteria developed in Amendment 25-64 focused primarily on
these seats. Since adoption of Amendment 25-64, several airplanes with
both forward-facing and aft-facing seats have been certificated using
the criteria in Amendment 25-64, and two airplanes with single-place
side-facing seats have been certificated using equivalent criteria
defined in an issue paper.

The criteria applied to each certification was somewhat different,
although the approaches were quite similar. This issue paper is intended
to provide a standardized methodology to address all such approvals in
the future. Since the regulations do not address side-facing seats,
these criteria should be documented in Special Conditions.

**FAA POSITION:** In addition to the airworthiness standards in
§§ 25.562 and 25.785, the following proposed special condition provides
injury criteria and installation/testing guidelines represent the
minimum acceptable airworthiness standard for side facing seats:

**1. The Proposed Injury Criteria**

\(a\) [Existing Criteria]{.underline}: All injury protection criteria of
§ 25.562(c)(1) through (c)(6) apply to the occupant of a side facing
seat. HIC assessments are only required for head contact with the seat
and/or adjacent structures.

\(b\) [Body-to-wall/furnishing contact]{.underline}: The seat must be
installed aft of a structure such as an interior wall or furnishing that
will support the pelviI ws, upper arm, chest, and head of an occupant
seated next to the structure. A conservative representation of the
structure and its stiffness must be included in the tests. The contact
surface of this structure must be covered with at least two inches of
energy absorbing protective foam, such as ensolite.

\(c\) [Thoracic Trauma]{.underline}: Testing with a Side Impact Dummy
(SID), as defined by 49 CFR Part 572, Subpart F, or its equivalent, must
be conducted and Thoracic Trauma Index (TTI) injury criteria acquired
with the SID must be less than 85, as defined in 49 CFR Part 572,
Subpart F. SID TTI data must be processed as defined in Federal Motor
Vehicle Safety Standard (FMVSS) Part 571.214, section S6.13.5. Rational
analysis, comparing an installation with another installation where TTI
data were acquired and found acceptable, may also be viable.

\(d\) [Pelvis]{.underline}: Pelvic lateral acceleration must not exceed
130g. Pelvic acceleration data must be processed as defined in FMVSS
Part 571.214, section S6.13.5.

\(e\) [Shoulder Strap Loads]{.underline}: Where upper torso straps
(shoulder straps) are used for occupants, tension loads in individual
straps must not exceed 1,750 pounds. If dual straps are used for
restraining the upper torso, the total strap tension loads must not
exceed 2,000 pounds.

**2. General Test Guidelines**

(a) One test with the SID ATD, undeformed floor, no yaw, and with all
    lateral structural supports (armrests/walls).

Pass/fail injury assessments: TTI; and pelvic acceleration.

\(b\) One test with the Hybrid II ATD, deformed floor, with 10 degrees
yaw, and with all lateral structural supports (armrests/walls).

Pass/fail injury assessments: HIC; and upper torso restraint load,
restraint system retention and pelvic acceleration.

\(c\) Vertical (14 G\'s) test to be conducted with modified Hybrid II
ATDs with existing pass/fail criteria.

**FCAA POSITION:**

Open.

**APPLICANT\'S POSITION:**

Open.

**CONCLUSION:**

Open.