[Federal Register Volume 78, Number 158 (Thursday, August 15, 2013)]
[Rules and Regulations]
[Pages 49655-49660]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2013-19754]
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Rules and Regulations
Federal Register
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Federal Register / Vol. 78, No. 158 / Thursday, August 15, 2013 /
Rules and Regulations
[[Page 49655]]
DEPARTMENT OF TRANSPORTATION
Federal Aviation Administration
14 CFR Part 25
[Docket No. FAA-2013-0384; Special Conditions No. 25-495-SC]
Special Conditions: Embraer, S.A., Model EMB-550 Airplane; Side-
Facing Seats; Installation of Airbag Systems in Shoulder Belts
AGENCY: Federal Aviation Administration (FAA), DOT.
ACTION: Final special conditions.
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SUMMARY: These special conditions are issued for the Embraer S.A. Model
EMB-550 airplane. This airplane will have a novel or unusual design
feature associated with multiple-place and single-place side-facing
seats and the installation of airbag systems in the shoulder belts. The
applicable airworthiness regulations do not contain adequate or
appropriate safety standards for this design feature. These special
conditions contain the additional safety standards that the
Administrator considers necessary to establish a level of safety
equivalent to that established by the existing airworthiness standards.
DATES: Effective Date: September 16, 2013.
FOR FURTHER INFORMATION CONTACT: Jayson Claar, FAA, Airframe and Cabin
Safety Branch, ANM-115, Transport Airplane Directorate, Aircraft
Certification Service, 1601 Lind Avenue SW., Renton, Washington 98057-
3356; telephone 425-227-2194; facsimile 425-227-1232.
SUPPLEMENTARY INFORMATION:
Background
On May 14, 2009, Embraer S.A. applied for a type certificate for
its new Model EMB-550 airplane. The Model EMB-550 airplane is the first
of a new family of jet airplanes designed for corporate flight,
fractional, charter, and private owner operations. The airplane has a
conventional configuration with low wing and T-tail empennage. The
primary structure is metal with composite empennage and control
surfaces. The Model EMB-550 airplane is designed for 8 passengers, with
a maximum of 12 passengers. It is equipped with two Honeywell HTF7500-E
medium bypass ratio turbofan engines mounted on aft fuselage pylons.
Each engine produces approximately 6,540 pounds (lbs) of thrust for
normal takeoff. The primary flight controls consist of hydraulically
powered fly-by-wire elevators, aileron and rudder, controlled by the
pilot or copilot sidestick.
The Model EMB-550 airplane has interior configurations that include
multiple-place side-facing seats and single-place side-facing seats
(both referred to as side-facing seats) that include airbag systems in
the shoulder belts for these seats. Existing regulations do not provide
adequate or appropriate safety standards for occupants of side-facing
seats. Also, existing regulations do not provide adequate or
appropriate safety standards for the addition of airbag systems in the
shoulder belt of side-facing seats. These special conditions address
both issues.
Type Certification Basis
Under the provisions of Title 14, Code of Federal Regulations (14
CFR) 21.17, Embraer S.A. must show that the Model EMB-550 airplane
meets the applicable provisions of part 25, as amended by Amendments
25-1 through 25-127 thereto.
If the Administrator finds that the applicable airworthiness
regulations (i.e., 14 CFR part 25) do not contain adequate or
appropriate safety standards for the Embraer S.A. Model EMB-550
airplane because of a novel or unusual design feature, special
conditions are prescribed under the provisions of Sec. 21.16.
Special conditions are initially applicable to the model for which
they are issued. Should the type certificate for that model be amended
later to include any other model that incorporates the same or similar
novel or unusual design feature, the special conditions would also
apply to the other model under Sec. 21.101.
In addition to the applicable airworthiness regulations and special
conditions, the Embraer S.A. Model EMB-550 airplane must comply with
the fuel vent and exhaust emission requirements of 14 CFR part 34 and
the noise certification requirements of 14 CFR part 36 and the FAA must
issue a finding of regulatory adequacy under Sec. 611 of Public Law
92-574, the ``Noise Control Act of 1972.''
The FAA issues special conditions, as defined in 14 CFR 11.19, in
accordance with Sec. 11.38, and they become part of the type-
certification basis under Sec. 21.17(a)(2).
Novel or Unusual Design Features
The Embraer S.A. Model EMB-550 airplane will incorporate the
following novel or unusual design features: side-facing seats with
airbag systems in the shoulder belts.
The Model EMB-550 airplane will have interior configurations with
multiple-place side-facing seats and single-place side-facing seats
that include airbag systems in the shoulder belts. Side-facing seats
are considered a novel design for transport category airplanes that
include Amendment 25-64 in their certification basis and were not
anticipated when those airworthiness standards were issued. Therefore,
the existing regulations do not provide adequate or appropriate safety
standards for occupants of side-facing seats. The airbag systems in the
shoulder belts are designed to limit occupant forward excursion in the
event of an accident. Using airbag systems in the shoulder belts is
novel for commercial aviation.
Discussion
The FAA has been conducting research to develop an acceptable
method of compliance with Title 14, Code of Federal Regulations (14
CFR) 25.785(b) for side-facing seat installations. That research has
identified additional injury considerations and evaluation criteria.
See published report DOT/FAA/AR-09/41, July 2011.
Before this research, the FAA had been granting exemptions for the
multiple-place side-facing seat installations since an adequate method
of compliance was not available to produce an equivalent level of
safety to that level of safety provided for the forward- and aft-facing
seats. These
[[Page 49656]]
exemptions were subject to many conditions that reflected the injury
evaluation criteria and mitigation strategies available at the time of
the exemption issuance. The FAA has now developed a methodology to
address all fully side-facing seats (i.e., seats oriented in the
aircraft with the occupant facing 90 degrees to the direction of
aircraft travel) and is documenting those requirements in these special
conditions. Some of the previous conditions issued for exemptions are
still relevant and are included in these new special conditions.
However, many of the conditions for exemption have been replaced by
different criteria that reflect current research findings.
The FAA had been issuing special conditions to address single-place
side-facing seats; however, application of the current research
findings has allowed issuing special conditions that are applicable to
all fully side-facing seats, both multiple-place and single-place.
Neck-injury evaluation methods applicable to the most common side-
facing seat configurations were identified during recent FAA research.
The scope of that research, however, did not include deriving specific
injury criteria for all possible loading scenarios that could occur to
occupants of fully side-facing seats. To limit the injury risk in those
cases, these special conditions provide conservative injury evaluation
means that are derived from past practice and applicable scientific
literature.
Serious leg injuries, such as femur fractures, can occur in
aviation side-facing seats that could threaten the occupants' lives
directly or reduce their ability to evacuate. Limiting upper-leg axial
rotation to a conservative limit of 35 degrees (approximately the 50
percentile range of motion) should also limit the risk of serious leg
injuries. It is believed that the angle of rotation can be determined
by observing lower-leg flailing in typical high-speed video of the
dynamic tests. This requirement complies with the intent of the Sec.
25.562 (b)(6) injury criteria in preventing serious leg injury.
The requirement to provide support for the pelvis, upper arm,
chest, and head contained in the previous special conditions for
single-place side-facing seats, has been replaced in the new special
conditions applicable to all fully side-facing seats with requirements
for neck-injury evaluation, leg-flailing limits, pelvis-excursion
limits, head-excursion limits, and torso lateral-bending limits that
directly assess the effectiveness of the support provided by the seat
and restraint system.
To protect occupants in aft-facing seats, those seats must have
sufficient height and stiffness to support their heads and spines.
Providing this support is intended to reduce spinal injuries when
occupant inertial forces cause their heads and spines to load against
the seat backs. If, during a side-facing-seat dynamic test, the
flailing of the occupants causes their heads to translate beyond the
planes of the seat backs, then this lack of support would not comply
with the intent of the requirement to prevent spine injuries and would
not provide the same level of safety afforded occupants of forward- and
aft-facing seats.
Results from tests that produced lateral flailing over an armrest
indicate that serious injuries, including spinal fractures, would
likely occur. While no criteria currently relates the amount of lateral
flail to a specific risk of injury, if lateral flexion is limited to
the normal static range of motion, then the risk of injury should be
low. This range of motion is approximately 40 degrees from the upright
position. Ensuring that lateral flexion does not create a significant
injury risk is consistent with the goal of providing an equivalent
level of safety to that provided by forward- or aft-facing seats,
because that type of articulation of those seats does not occur during
forward impacts.
Section 25.562 requires that the restraints remain on the shoulders
and pelvises of the occupants during impact. Advisory Circular (AC)
25.562-1B, Dynamic Evaluation of Seat Restraint Systems and Occupant
Protection on Transport Airplanes, dated January 10, 2006, clarifies
this requirement by stating that restraints must remain on the
shoulders and pelvises when loaded by the occupants. This criterion is
necessary to protect the occupants from serious injuries that could be
caused by lap-belt contact forces applied to soft tissue or by
ineffectively restraining the upper torsos caused by the upper torso
restraints sliding off the shoulders. In forward-facing seats (the type
specifically addressed by that AC), occupant motion during rebound and
any subsequent re-loading of the belts is limited by interaction with
the seat backs. However, in side-facing seats subjected to a forward
impact, the restraint systems may be the only means of limiting the
occupants' rearward (rebound) motion. So to limit abdominal injury risk
in side-facing seats, the lap belts must remain on the pelvis
throughout the impact event, including rebound.
During side-facing-seat dynamic tests, the risk for head injury is
assessed with only one occupant size (the 50th percentile male as
represented by the ES-2re as defined in 49 CFR part 572 supbart U).
However, protection for a range of occupant statures can be provided if
the impacted surface is homogenous in the area contactable by that
range of occupants.
The FAA has issued special conditions in the past for airbag
systems on lap belts for some forward-facing seats. These special
conditions for the airbag systems in the shoulder belts are based on
the previous special conditions for airbag systems on lap belts with
some changes to address the specific issues of side-facing seats. The
special conditions are not an installation approval. Therefore, while
the special conditions relate to each such system installed, the
overall installation approval is a separate finding and must consider
the combined effects of all such systems installed.
The FAA has considered the installation of airbag systems in the
shoulder belts to have two primary safety concerns: first, that the
systems perform properly under foreseeable operating conditions, and
second, that the systems do not perform in a manner or at such times as
would constitute a hazard to the occupants. This latter point has the
potential to be the more rigorous of the requirements, owing to the
active nature of the system.
For the reasons discussed above, these special conditions contain
the additional safety standards that the Administrator considers
necessary to establish a level of safety equivalent to that established
by the existing airworthiness standards.
Discussion of Comments
Notice of proposed special conditions No. 25-13-02-SC for the
Embraer Model EMB-550 airplanes was published in the Federal Register
on May 6, 2013 (78 FR 26280). No comments were received, and the
special conditions are adopted as proposed.
Applicability
As discussed above, these special conditions are applicable to the
Embraer Model EMB-550 airplane. Should Embraer S.A. the same novel or
unusual design feature, the special conditions would apply to that
model as well.
Conclusion
This action affects only certain novel or unusual design features
on one model of airplanes. It is not a rule of general applicability.
[[Page 49657]]
List of Subjects in 14 CFR Part 25
Aircraft, Aviation safety, Reporting and recordkeeping
requirements.
The authority citation for these special conditions is as follows:
Authority: 49 U.S.C. 106(g), 40113, 44701, 44702, 44704.
The Special Conditions
Accordingly, pursuant to the authority delegated to me by the
Administrator, the following special conditions are issued as part of
the type certification basis for Embraer Model EMB-550 airplanes.
In addition to the requirements of Sec. Sec. 25.562 and 25.785,
the following special condition numbers 1 and 2 are part of the type
certification basis of the Model EMB-550 airplane with side-facing-seat
installations. For seat places equipped with airbag systems in the
shoulder belts, additional special condition numbers 3 through 16 are
part of the type certification basis.
1. Additional requirements applicable to tests or rational analysis
conducted to show compliance with Sec. Sec. 25.562 and 25.785 for
side-facing seats:
(a) The longitudinal test(s) conducted in accordance with Sec.
25.562(b)(2) to show compliance with the seat-strength requirements of
Sec. 25.562(c)(7) and (8) and these special conditions must have an
ES-2re anthropomorphic test dummy (ATD) (49 CFR part 572 subpart U) or
equivalent, or a Hybrid-II ATD (49 CFR part 572, subpart B as specified
in Sec. 25.562) or equivalent occupying each seat position and
including all items contactable by the occupant (e.g., armrest,
interior wall, or furnishing) if those items are necessary to restrain
the occupant. If included, the floor representation and contactable
items must be located such that their relative position, with respect
to the center of the nearest seat place, is the same at the start of
the test as before floor misalignment is applied. For example, if floor
misalignment rotates the centerline of the seat place nearest the
contactable item 8 degrees clockwise about the aircraft x-axis, then
the item and floor representations must be rotated by 8 degrees
clockwise also to maintain the same relative position to the seat
place, as shown in Figure 1. Each ATD's relative position to the seat
after application of floor misalignment must be the same as before
misalignment is applied. To ensure proper loading of the seat by the
occupants, the ATD pelvis must remain supported by the seat pan, and
the restraint system must remain on the pelvis and shoulder of the ATD
until rebound begins. No injury-criteria evaluation is necessary for
tests conducted only to assess seat-strength requirements.
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(b) The longitudinal test(s) conducted in accordance with Sec.
25.562(b)(2) to show compliance with the injury assessments required by
Sec. 25.562(c) and these special conditions may be conducted
separately from the test(s) to show structural integrity. In this case,
structural-assessment tests must be conducted as specified in paragraph
1(a)
[[Page 49658]]
of these special conditions, and the injury-assessment test must be
conducted without yaw or floor misalignment. Injury assessments may be
accomplished by testing with ES-2re ATD (49 CFR part 572 subpart U) or
equivalent at all places. Alternatively, these assessments may be
accomplished by multiple tests that use an ES-2re at the seat place
being evaluated and a Hybrid-II ATD (49 CFR part 572, subpart B, as
specified in Sec. 25.562) or equivalent used in all seat places
forward of the one being assessed to evaluate occupant interaction. In
this case, seat places aft of the one being assessed may be unoccupied.
If a seat installation includes adjacent items that are contactable by
the occupant, the injury potential of that contact must be assessed. To
make this assessment, tests may be conducted that include the actual
item located and attached in a representative fashion. Alternatively,
the injury potential may be assessed by a combination of tests with
items having the same geometry as the actual item but having stiffness
characteristics that would create the worst case for injury (injuries
due to both contact with the item and lack of support from the item).
(c) If a seat is installed aft of a structure (e.g., an interior
wall or furnishing) that does not have a homogeneous surface
contactable by the occupant, additional analysis and/or test(s) may be
required to demonstrate that the injury criteria are met for the area
which an occupant could contact. For example, different yaw angles
could result in different injury considerations and may require
additional analysis or separate test(s) to evaluate.
(d) To accommodate a range of occupant heights (5th percentile
female to 95th percentile male), the surface of items contactable by
the occupant must be homogenous 7.3 inches (185 mm) above and 7.9
inches (200 mm) below the point (center of area) that is contacted by
the 50th percentile male size ATD's head during the longitudinal
test(s) conducted in accordance with paragraphs 1(a), 1(b), and 1(c) of
these special conditions. Otherwise, additional head-injury criteria
(HIC) assessment tests may be necessary. Any surface (inflatable or
otherwise) that provides support for the occupant of any seat place
must provide that support in a consistent manner regardless of occupant
stature. For example, if an inflatable shoulder belt is used to
mitigate injury risk, then it must be demonstrated by inspection to
bear against the range of occupants in a similar manner before and
after inflation. Likewise, the means of limiting lower-leg flail must
be demonstrated by inspection to provide protection for the range of
occupants in a similar manner.
(e) For longitudinal test(s) conducted in accordance with Sec.
25.562(b)(2) and these special conditions, the ATDs must be positioned,
clothed, and have lateral instrumentation configured as follows:
(1) ATD positioning:
(i) Lower the ATD vertically into the seat while simultaneously
(see Figure 2 for illustration):
[[Page 49659]]
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(A) Aligning the midsagittal plane (a vertical plane through the
midline of the body; dividing the body into right and left halves) with
approximately the middle of the seat place.
(B) Applying a horizontal x-axis direction (in the ATD coordinate
system) force of about 20 pounds (lbs) (89 Newtons [N]) to the torso at
approximately the intersection of the midsagittal plane and the bottom
rib of the ES-2re or lower sternum of the Hybrid-II at the midsagittal
plane, to compress the seat back cushion.
(C) Keeping the upper legs nearly horizontal by supporting them
just behind the knees.
(ii) Once all lifting devices have been removed from the ATD:
(A) Rock it slightly to settle it in the seat.
(B) Separate the knees by about 4 inches (100 mm).
(C) Set the ES-2re's head at approximately the midpoint of the
available range of z-axis rotation (to align the head and torso
midsagittal planes).
(D) Position the ES-2re's arms at the joint's mechanical detent
that puts them at approximately a 40-degree angle with respect to the
torso. Position the Hybrid-II ATD hands on top of its upper legs.
(E) Position the feet such that the centerlines of the lower legs
are approximately parallel to a lateral vertical plane (in the aircraft
coordinate system).
(2) ATD clothing: Clothe each ATD in form-fitting, mid-calf-length
(minimum) pants and shoes (size 11E) weighing about 2.5 lb (1.1 kg)
total. The color of the clothing should be in contrast to the color of
the restraint system. The ES-2re jacket is sufficient for torso
clothing, although a form-fitting shirt may be used in addition if
desired.
(3) ES-2re ATD lateral instrumentation: The rib-module linear
slides are directional, i.e., deflection occurs in either a positive or
negative ATD y-axis direction. The modules must be installed such that
the moving end of the rib module is toward the front of the aircraft.
The three abdominal force sensors must be installed such that they are
on the side of the ATD toward the front of the aircraft.
(f) The combined horizontal/vertical test, required by Sec.
25.562(b)(1) and these special conditions, must be conducted with a
Hybrid II ATD (49 CFR part 572, subpart B, as specified in Sec.
25.562), or equivalent, occupying each seat position.
(g) Restraint systems:
(1) If inflatable restraint systems are used, they must be active
during all dynamic tests conducted to show compliance with Sec.
25.562.
(2) The design and installation of seat-belt buckles must prevent
unbuckling due to applied inertial forces or impact of the hands/arms
of the occupant during an emergency landing.
[[Page 49660]]
2. Additional performance measures applicable to tests and rational
analysis conducted to show compliance with Sec. Sec. 25.562 and 25.785
for side-facing seats:
(a) Body-to-body contact: Contact between the head, pelvis, torso,
or shoulder area of one ATD with the adjacent-seated ATD's head,
pelvis, torso, or shoulder area is not allowed. Contact during rebound
is allowed.
(b) Thoracic: The deflection of any of the ES-2re ATD upper,
middle, and lower ribs must not exceed 1.73 inches (44 mm). Data must
be processed as defined in Federal Motor Vehicle Safety Standards
(FMVSS) 571.214.
(c) Abdominal: The sum of the measured ES-2re ATD front, middle,
and rear abdominal forces must not exceed 562 lb (2,500 N). Data must
be processed as defined in FMVSS 571.214.
(d) Pelvic: The pubic symphysis force measured by the ES-2re ATD
must not exceed 1,350 lb (6,000 N). Data must be processed as defined
in FMVSS 571.214.
(e) Leg: Axial rotation of the upper-leg (femur) must be limited to
35 degrees in either direction from the nominal seated position.
(f) Neck: As measured by the ES-2re ATD and filtered at channel
frequency class (CFC) 600 as defined in SAE J211:
(1) The upper-neck tension force at the occipital condyle location
must be less than 405 lb (1,800 N).
(2) The upper-neck compression force at the occipital condyle
location must be less than 405 lb (1,800 N).
(3) The upper-neck bending torque about the ATD x-axis at the
occipital condyle location must be less than 1,018 in-lb (115 Nm).
(4) The upper-neck resultant shear force at the occipital condyle
location must be less than 186 lb (825 N).
(g) Occupant (ES-2re ATD) retention: The pelvic restraint must
remain on the ES-2re ATD's pelvis during the impact and rebound phases
of the test. The upper-torso restraint straps (if present) must remain
on the ATD's shoulder during the impact.
(h) Occupant (ES-2re ATD) support:
(1) Pelvis excursion: The load-bearing portion of the bottom of the
ATD pelvis must not translate beyond the edges of its seat's bottom
seat-cushion supporting structure.
(2) Upper-torso support: The lateral flexion of the ATD torso must
not exceed 40 degrees from the normal upright position during the
impact.
3. For seats with airbag systems in the shoulder belts, show that
the airbag systems in the shoulder belts will deploy and provide
protection under crash conditions where it is necessary to prevent
serious injury. The means of protection must take into consideration a
range of stature from a 2-year-old child to a 95th percentile male. The
airbag systems in the shoulder belts must provide a consistent approach
to energy absorption throughout that range of occupants. When the seat
systems include airbag systems, the systems must be included in each of
the certification tests as they would be installed in the airplane. In
addition, the following situations must be considered:
(a) The seat occupant is holding an infant.
(b) The seat occupant is a pregnant woman.
4. The airbag systems in the shoulder belts must provide adequate
protection for each occupant regardless of the number of occupants of
the seat assembly, considering that unoccupied seats may have active
airbag systems in the shoulder belts.
5. The design must prevent the airbag systems in the shoulder belts
from being either incorrectly buckled or incorrectly installed, such
that the airbag systems in the shoulder belts would not properly
deploy. Alternatively, it must be shown that such deployment is not
hazardous to the occupant and will provide the required injury
protection.
6. It must be shown that the airbag systems in the shoulder belts
are not susceptible to inadvertent deployment as a result of wear and
tear, inertial loads resulting from in-flight or ground maneuvers
(e.g., including gusts and hard landings), and other operating and
environmental conditions (e.g., vibrations and moisture) likely to
occur in service.
7. Deployment of the airbag systems in the shoulder belts must not
introduce injury mechanisms to the seated occupants or result in
injuries that could impede rapid egress. This assessment should include
an occupant whose belt is loosely fastened.
8. It must be shown that inadvertent deployment of the airbag
systems in the shoulder belts, during the most critical part of the
flight, will either meet the requirement of Sec. 25.1309(b) or not
cause a hazard to the airplane or its occupants.
9. It must be shown that the airbag systems in the shoulder belts
will not impede rapid egress of occupants 10 seconds after airbag
deployment.
10. The airbag systems must be protected from lightning and high-
intensity radiated fields (HIRF). The threats to the airplane specified
in existing regulations regarding lighting, Sec. 25.1316, and HIRF,
Sec. 25.1317, are incorporated by reference for the purpose of
measuring lightning and HIRF protection.
11. The airbag systems in the shoulder belts must function properly
after loss of normal aircraft electrical power and after a transverse
separation of the fuselage at the most critical location. A separation
at the location of the airbag systems in the shoulder belts does not
have to be considered.
12. It must be shown that the airbag systems in the shoulder belts
will not release hazardous quantities of gas or particulate matter into
the cabin.
13. The airbag systems in the shoulder-belt installations must be
protected from the effects of fire such that no hazard to occupants
will result.
14. A means must be available for a crew member to verify the
integrity of the airbag systems in the shoulder-belts activation system
prior to each flight or it must be demonstrated to reliably operate
between inspection intervals. The FAA considers that the loss of the
airbag-system deployment function alone (i.e., independent of the
conditional event that requires the airbag-system deployment) is a
major-failure condition.
15. The inflatable material may not have an average burn rate of
greater than 2.5 inches/minute when tested using the horizontal
flammability test defined in part 25, appendix F, part I, paragraph
(b)(5).
16. Once deployed, the airbag systems in the shoulder belts must
not adversely affect the emergency-lighting system (e.g., block floor
proximity lights to the extent that the lights no longer meet their
intended function).
Issued in Renton, Washington, on August 9, 2013.
Jeffrey E. Duven,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 2013-19754 Filed 8-14-13; 8:45 am]
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