Federal Motor Vehicle Safety Standards; Head Restraints

Federal Motor Vehicle Safety Standards; Head Restraints

Topics: National Highway Traffic Safety Administration

Federal Motor Vehicle Safety Standards; Head Restraints

David L. Strickland
November 2, 2010

[Federal Register: November 2, 2010 (Volume 75, Number 211)]
[Rules and Regulations]
[Page 67233-67247]
From the Federal Register Online via GPO Access [wais.access.gpo.gov]
[DOCID:fr02no10-7]

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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Part 571

[Docket No. NHTSA-2010-0148]
RIN 2127-AK39

Federal Motor Vehicle Safety Standards; Head Restraints

AGENCY: National Highway Traffic Safety Administration (NHTSA), DOT.

ACTION: Final rule; technical amendments; response to petitions for
reconsideration and petitions for rulemaking.

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SUMMARY: This document responds to petitions for reconsideration of the
agency's May 2007 final rule amending our head restraint standard, and
to related petitions for rulemaking. This document also makes technical
corrections. The May 2007 final rule was issued in response to
petitions for reconsideration of our December 2004 final rule upgrading
our head restraint standard. We are partially granting and partially
denying the petitions for reconsideration.

[[Page 67234]]

DATES: Effective Date: This rule is effective January 3, 2011.
Petitions: Petitions for reconsideration must be received by December
17, 2010.

ADDRESSES: Any petitions for reconsideration should refer to the docket
number of this document and be submitted to: Administrator, National
Highway Traffic Safety Administration, 1200 New Jersey Avenue, SE.,
West Building, Ground Floor, Docket Room W12-140, Washington, DC 20590.
The petition will be placed in the docket. Anyone is able to search
the electronic form of all documents received into any of our dockets
by the name of the individual submitting the document (or signing the
document, if submitted on behalf of an association, business, labor
union, etc.). You may review DOT's complete Privacy Act Statement in
the Federal Register published on April 11, 2000 (Volume 65, Number 70;
Pages 19477-78).

FOR FURTHER INFORMATION CONTACT: For non-legal issues, you may contact
Louis Molino of the Office of Rulemaking, Office of Crashworthiness
Standards, Light Duty Vehicle Division, NVS-112, (Phone: 202-366-1740).
For legal issues, you may contact Edward Glancy of the Office of Chief
Counsel, NCC-112, (Phone: 202-366-2992). You may send mail to both of
these officials at the National Highway Traffic Safety Administration,
1200 New Jersey Avenue, SE., Washington, DC 20590.

SUPPLEMENTARY INFORMATION:

Table of Contents

I. Overview
II. Background
A. Introduction
B. Agency Goals in Upgrading Head Restraint Standard
C. May 2007 Final Rule; Response to Petitions for
Reconsideration
D. Global Technical Regulation on Head Restraints
E. Petitions for Reconsideration of May 2007 Final Rule and
Related Submissions
1. Petitions for Reconsideration
a. Rear Seat Non-Use Positions
b. Leadtime for Small Vehicle Manufacturers
c. Static Lockout of Active Head Restraints During Backset
Retention Testing
d. Clarifying Definition of Adjustable Head Restraints
e. Technical Amendments
2. Petitions for Rulemaking
a. Discomfort Metric for Non-Use Position and Relaxation
Requirement for Gap
b. ``Effective Backset''
III. Agency Response to Petitions for Reconsideration of May 2007
Final Rule and Technical Amendments
A. NHTSA Declines To Adopt a 5-Degree Torso Change Angle for
Rear Seat Non-Use Positions
B. NHTSA Declines To Permit Additional Leadtime for Small
Vehicle Manufacturers
C. Static Lockout of Active Head Restraints During Backset
Retention Testing
1. NHTSA Agrees To Specify the Fixation Point for Static Testing
of Active Mechanical Head Restraints
2. NHTSA Declines To Specify a Minimum Forward Movement
Requirement for Static Testing of Active Mechanical Head Restraints
3. NHTSA Declines To Expand the Fixation Option to ``Reactive''
and Electronically Triggered Head Restraints
D. ``Adjustable'' Head Restraints and Availability of 25 mm
Cylindrical Gap Test Option
E. Technical Amendments and Corrections
1. NHTSA Agrees To Revise S5.2.4.2
2. NHTSA Agrees To Revise S5.3.4
3. NHTSA Agrees To Revise S5.2.6(d) and S5.2.7(a)(7)
4. NHTSA Agrees To Revise S5.2.7(a)(5)
5. NHTSA Is Correcting Clerical Errors in S4.3 and S5.3
IV. Agency Response to Petitions for Rulemaking
A. NHTSA Declines To Conduct Rulemaking Concerning Discomfort
Metric or Relaxation Requirement for Gap Separate From the
Rulemaking Based on the GTR
B. NHTSA Denies Petition for Rulemaking To Replace the Current
Backset Measurement Method With an ``Effective Backset'' Requirement
C. NHTSA Denies Petition for Rulemaking To Adopt Effective
Backset Requirements for Front and Rear Head Restraints as
Alternative to Backset Retention Requirement
V. Rulemaking Analyses and Notices

I. Overview

This document responds to petitions for reconsideration of the
agency's May 2007 final rule amending our head restraint standard, and
to related petitions for rulemaking. This document also makes technical
corrections.
The May 2007 final rule was issued in response to petitions for
reconsideration of our December 2004 final rule upgrading our head
restraint standard. The December 2004 final rule represented a
significant upgrade of NHTSA's head restraint standard, and the
estimated benefits, recognized primarily by reductions in ``whiplash''
injuries, were substantial. The overwhelming majority of those benefits
came from reducing the ``backset,'' or distance between the back of the
head and the head restraint.
We also note that further rulemaking on this subject is upcoming. A
Global Technical Regulation (GTR) on the subject has recently been
adopted, and NHTSA plans to publish a notice of proposed rulemaking
(NPRM) to propose changes in accordance with the GTR.
In this document, we are partially granting and partially denying
the petitions for reconsideration of our May 2007 final rule. Some of
the issues raised by the petitioners for rulemaking are addressed by
the GTR. We will address those issues in the context of a future
separate rulemaking based on the GTR. We are otherwise denying the
petitions for rulemaking.

II. Background

A. Introduction

On December 14, 2004, NHTSA published in the Federal Register (69
FR 74848) a final rule \1\ upgrading the agency's head restraint
standard in order to reduce whiplash injuries in rear collisions. The
upgraded standard specified requirements for front seat head restraints
and for head restraints voluntarily installed in rear outboard
designated seating positions.
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\1\ Docket No. NHTSA-2004-19807.
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On May 4, 2007, NHTSA published in the Federal Register (72 FR
25484) a final rule; response to petitions for reconsideration \2\
which completed the agency's response to petitions for reconsideration
of the December 2004 final rule. The agency partially granted and
partially denied the petitions. The agency also denied a related
petition for rulemaking, submitted by Kongsberg Automotive (Kongsberg),
in that document. Kongsberg is a company that produces automotive
parts, including head restraint systems.
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\2\ Docket No. NHTSA-2007-27986.
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The upgraded standard is designated Standard No. 202a; Head
Restraints; Mandatory applicability begins on September 1, 2009. The
earlier standard is Standard No. 202; Head Restraints; Applicable at
the manufacturers' option until September 1, 2009. The requirements of
the upgraded standard are currently being phased in.
In today's document, we are responding to petitions for
reconsideration received in response to the May 2007 final rule, and to
related petitions for rulemaking. Readers who may be interested in the
broader issues involved in the rulemaking to upgrade the head restraint
standard are encouraged to read the December 2004 and May 2007 final
rules.

B. Agency Goals in Upgrading Head Restraint Standard

The agency upgraded its head restraint standard in order to reduce
whiplash injuries in rear collisions. Whiplash injuries are a set of
common symptoms that occur in motor vehicle crashes and involve the
soft tissues of the head, neck and spine. Symptoms of

[[Page 67235]]

pain in the head, neck, shoulders, and arms may be present along with
damage to muscles, ligaments and vertebrae, but in many cases lesions
are not evident. The onset of symptoms may be delayed and may only last
a few hours; however, in some cases, effects of the injury may last for
years or even be permanent. The relatively short-term symptoms are
associated with muscle and ligament trauma, while the long-term ones
are associated with nerve damage.
Based on National Automotive Sampling System (NASS) data, we
estimate that between 1988 and 1996, 805,581 whiplash injuries \3\
occurred annually in crashes involving passenger cars and LTVs (light
trucks, multipurpose passenger vehicles, and vans). Of these whiplash
injuries, 272,464 occurred as a result of rear impacts. For rear impact
crashes, the average cost of whiplash injuries in 2002 dollars is
$9,994 (which includes $6,843 in economic costs and $3,151 in quality
of life impacts, but not property damage), resulting in a total annual
cost of approximately $2.7 billion.
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\3\ Non-contact Abbreviated Injury Scale (AIS) 1 neck.
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Although whiplash injuries can occur in any kind of crash, an
occupant's chances of sustaining this type of injury are greatest in
rear-end collisions. When a vehicle is struck from behind, typically
several things occur in quick succession to an occupant of that
vehicle. First, from the occupant's frame of reference, the back of the
seat moves forward into his or her torso, straightening the spine and
forcing the head to rise vertically. Second, as the seat pushes the
occupant's body forward, the unrestrained head tends to lag behind.
This causes the neck to change shape, first taking on an S-shape and
then bending backward. Third, the forces on the neck accelerate the
head, which catches up with--and, depending on the seat back stiffness
and if the occupant is using a shoulder belt, passes--the restrained
torso. This motion of the head and neck, which is like the lash of a
whip, gives the resulting neck injuries their popular name.
NHTSA research has indicated that whiplash injuries can be
substantially reduced by limiting the distance between the back of the
head and the head restraint, a distance known as the ``backset.'' The
most significant effect of the 2004 final rule was to limit backset to
55 mm. In limiting backset, NHTSA balanced comfort, safety, and
measurement variability concerns. The agency explained the rationale
for the backset requirement in the preamble to the December 2004 final
rule, and addressed the issue further in the preamble to the May 2007
final rule.

C. May 2007 Final Rule; Response to Petitions for Reconsideration

As noted above, NHTSA's May 2007 final rule, response to petitions
for reconsideration, completed the agency's response to petitions for
reconsideration of the December 2004 final rule. The agency partially
granted and partially denied the petitions. The more significant
changes made in the May 2007 response to petitions included:
Leadtime: For the front seat requirements, the agency
provided one additional year of leadtime and also established a one-
year phase-in with an 80 percent requirement. NHTSA had previously
extended the compliance date for the rear seat requirements by two
years. The agency also established a one-year phase-in with an 80
percent requirement for the rear seat requirements.
Backset: NHTSA made two changes related to the backset
requirement. First, the agency specified in FMVSS No. 202a that backset
is determined by taking the arithmetic average of three measurements,
rather than using a single measurement. Two studies, one by NHTSA and
one by Transport Canada, had indicated that taking an average of
several measurements reduces variability. Second, we slightly relaxed
the backset requirement by specifying that the 55 mm backset limit
applies with the seat back at the vehicle manufacturer's specified
design angle rather than at 25 degrees. This decision reflected
consideration of interrelated issues and data concerning the 55 mm
backset limit, comfort, and seat back angle.
Rear Seat Non-Use Positions: To provide greater
flexibility in this area, we added (as included in the NPRM) an option
for a 10-degree change in the torso reference angle criteria.
Gaps Between Head Restraint and Seat Back: We added a
manufacturer option under which the gap requirement may be met by
either the existing FMVSS No. 202a procedure using a sphere or one
based on the measurement methodology set forth in United Nations
Economic Commission for Europe (UNECE or ECE) Regulation No. 17,
Uniform Provisions concerning the Approval of Vehicles with regard to
the Seats, their Anchorages, and any Head Restraints.
Backset and Height Retention (Lock) Tests: We specified
that instead of returning to the reference loads of 37 Nm and 50 N
after application of the peak load during these tests, that the load be
reduced to zero and then increased to the reference loads.
The agency also denied a related petition for rulemaking, submitted
by Kongsberg, in that document. Kongsberg's petition for rulemaking had
made requests in the areas of effective backset, backset retention and
displacement, height retention, non-use position, definition of rear
restraint, gaps, and removability of head restraints.

D. Global Technical Regulation on Head Restraints

In the preamble to the May 2007 final rule, we explained that the
agency had separately been leading efforts to develop a GTR on head
restraints We noted that the work on the GTR had been proceeding at the
same time that NHTSA had been evaluating the petitions for
reconsideration of the December 2004 final rule, and that some of the
issues that were the subject of the petitions for reconsideration had
also been raised in the context of the GTR.
We explained that in the May 2007 document, we were addressing
those issues in the context of the petitions for reconsideration of the
recently upgraded FMVSS No. 202. We explained further that if the
development of the GTR continued to proceed successfully and it was
ultimately adopted, and if the U.S. had voted for its adoption, NHTSA
would issue an NPRM based on the GTR for a new FMVSS.
After publication of the May 2007 document, the development of the
GTR on head restraints did continue to proceed successfully. It was
adopted in March 2008 by a vote taken by the World Forum for
Harmonization of Vehicle Regulations (WP.29). The U.S. voted for its
adoption. Prior to the vote, on February 14, 2008, NHTSA published in
the Federal Register (73 FR 8743) a request for comments \4\ on the GTR
to inform its decision on the vote.
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\4\ Docket No. NHTSA-2008-0016.
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The agency explained in the February 2008 request for comments that
once the GTR was established through consensus voting at WP.29, NHTSA
would initiate domestic rulemaking to amend its existing FMVSS to
incorporate approved provisions of the GTR. The agency explained that
this would allow for further opportunity to consider comments from
interested parties through the rulemaking process. NHTSA noted that if
its rulemaking process leads it to either not adopt or to modify
aspects of the GTR, the agency would seek to amend the GTR in
accordance with established procedures

[[Page 67236]]

under the 1998 Global Agreement and WP.29, as it did with the door lock
GTR.
NHTSA is currently in the process of developing an NPRM based on
the head restraints GTR.

E. Petitions for Reconsideration of May 2007 Final Rule and Related
Submissions

NHTSA received a total of seven submissions in response to, or
related to, the May 2007 final rule. These documents included ones
styled as petitions for reconsideration, petitions for expedited
rulemaking and a statement of support for one of the petitions for
expedited rulemaking.
While one of the documents, submitted by Kongsberg, was called a
petition for reconsideration, some of its requests are not for
reconsideration of the May 2007 final rule. Instead, they either
request reconsideration of the agency's denial of that company's
petition for rulemaking or are new requests for rulemaking. NHTSA does
not have procedures for requesting reconsideration of denials of
petitions for rulemaking. However, to the extent a petitioner provides
new information, the agency may consider such a document as a new
petition for rulemaking. We will treat these parts of Kongsberg's
petition as a petition for rulemaking.
Petitions for reconsideration of the May 2007 final rule were
received from the Alliance of Automobile Manufacturers (Alliance),
Vehicle Services Consulting, Inc. (VSCI), and Kongsberg. The Alliance
is a trade organization of motor vehicle manufacturers. VSCI is a
company that assists small volume vehicle manufacturers with U.S.
certification related matters.
Petitions for rulemaking were received from the Alliance,
Mitsubishi Motors R&D of America (Mitsubishi) and Kongsberg. The
Association of International Automobile Manufacturers (AIAM) submitted
a letter in support of the Mitsubishi petition.
The American Association for Justice (AAJ) submitted a document
that is styled as a petition for reconsideration and objects to the
agency's discussion of implied preemption. The agency does not consider
this to be a petition for reconsideration, as NHTSA's preemption
discussion is not a rule.
We believe that a fundamental misunderstanding lies at the heart of
petitioners' characterization of the discussion in the final rule. AAJ
has mistakenly characterized the agency's discussion of implied
preemption, a discussion that we included in approximately two dozen
other Federal motor vehicle safety standard rulemaking notices issued
from February 2007 to November 2008. We explained those discussions at
length in a June 14, 2010 final rule on FMVSS No. 305 (75 FR 33515, at
33524-33525), which we believe has addressed the concerns of AAJ and PC
on this subject.
To summarize the agency's discussion in the FMVSS No. 305 final
rule, in each of the Federal Register notices discussing Geier v.
American Honda Motor Co., 529 U.S. 861 (2000) and the agency's response
to Executive Order (E.O.) 13132, NHTSA sought to explain that we had
examined whether there might be any possible basis for a judicial
finding of implied preemption of state tort law. In all but a few of
those notices, we concluded each examination without identifying any
potential obstacle or conflict that might give rise to such a
finding.\5\ The FMVSS No. 305 final rule explained that the agency has
increasingly clarified and amplified its discussion responding to E.O.
13132 in an attempt to end the misunderstandings and assuage concerns
about the preemption discussion. Readers are referred to that document
for a full discussion of the language in question. Similarly, NHTSA
clarified the discussion of E.O. 13132 in the FMVSS No. 305 final rule.
The agency's discussion in that document should eliminate commenters'
misunderstandings about this topic.
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\5\ The May 2007 final rule on FMVSS No. 202a was one of many
notices in which we did not identify any potential obstacle or
conflict.
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The specific requests in the various petitions, broken down by
subject matter, are discussed briefly below.
1. Petitions for Reconsideration
a. Rear Seat Non-Use Positions
Under FMVSS No. 202a, head restraints installed in the rear seats
are permitted to have a ``non-use'' position, in which they are not
required to meet in-use performance requirements. Some of the reasons
for such a position are to help improve rear visibility, prevent the
head restraint from interfering with the seat being stowed, and to
facilitate child seat attachment. However, in developing the upgraded
head restraint standard, NHTSA was concerned that passengers may
inadvertently occupy the seat with the head restraint in the non-use
position, thereby depriving themselves of the whiplash protection
afforded by the head restraint.
In order to permit the non-use position, yet mitigate the potential
dangers, the agency required head restraints that can be adjusted to
such positions to meet one of three options, which are set forth in
paragraphs S4.4(a)-(c) of FMVSS No. 202a. One option (a) was that a
head restraint in a non-use position must automatically return to a
normal ``use position'' when the seat is occupied by a test dummy
representing a 5th percentile female. The second option (b) was that
the head restraint must be capable of manually rotating at least 60
degrees forward or rearward, between the use position and the non-use
position. This option, while not necessarily physically preventing a
passenger from sitting in a seat with the head restraint in the non-use
position, would at least provide a clear visible cue that the head
restraint was not properly adjusted. The third option (c) was that the
head restraint in the non-use position must cause the torso of a test
manikin to move forward by at least a 10-degree angle when compared to
its angle when the head restraint is in a use position. This has the
effect of making most passengers uncomfortable, which provides a strong
cue that the head restraint is not in the proper position.
Some petitioners for reconsideration requested that this third
option be broadened. Specifically, the Alliance requested that the
agency modify the standard by allowing a rear head restraint in the
non-use position to only cause the torso to move 5-10 degrees forward,
rather than at least 10. Essentially, the Alliance was asking that the
head restraint not have to jut out as much as it currently must in
order to provide the physical cue to the passenger that it is out of
position. There were two rationales offered for this. First, the
Alliance believed that it would be difficult to design stow-away
seating if the head restraint had to protrude so far as to cause the
torso angle to move forward 10 degrees. Second, the Alliance argued
that the mechanics required by the 10-degree torso angle change would
cause problems with certain child seats.
b. Leadtime for Small Vehicle Manufacturers
The agency was also petitioned to extend the leadtime for small
manufacturers. Specifically, VSCI petitioned the agency to permit
small-volume manufacturers (SVMs) to comply with FMVSS No. 202a only at
the end of the phase-in period, rather than having to phase in the new
head restraint requirements like other manufacturers. The standard
specifies that mandatory compliance begins on September 1, 2009, with
at least 80% of vehicles manufactured during the production year
beginning on that date being compliant with FMVSS No. 202a for front
seat head restraints. By

[[Page 67237]]

September 1, 2011, 100% of all head restraints in both the front and
rear seats must be compliant with the new standard.
The specific phase-in percentage requirements are shown by the
table below.

------------------------------------------------------------------------
Front Rear
Date seats seats
(%) (%)
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Production Year Beginning September 1, 2009........... 80 0
Production Year Beginning September 1, 2010........... 100 80
September 1, 2011..................................... 100 100
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VSCI requested that SVMs, that is, manufacturers which produce less
than 5,000 vehicles per year for sale in the U.S., not be required to
comply with FMVSS No. 202a until September 1, 2011, the end of the
phase-in period. VSCI's reasoning is that if a SVM produces only one
line of vehicles, if it changes the head restraint for one vehicle, it
changes it for 100% of its line. Thus, unless a SVM has more than four
vehicle lines, requiring 80% compliance is no different than requiring
100% compliance. Furthermore, VSCI suggests that an extension of the
effective compliance date could help SVMs integrate the new head
restraint requirements with the start of a new product cycle, rather
than having to integrate them in the middle or end of a cycle.
Finally, VSCI argues generally that SVMs should always be permitted
to comply with new standards at the end of phase-in cycles, due to the
fact that the nature of their businesses frequently make partial
compliance with standards not an option. VSCI also requested that the
agency formally adopt VSCI's definition of a SVM, which is: ``an
original vehicle manufacturer that produces or assembles fewer than
5,000 vehicles annually for sale in the United States.''
c. Static Lockout of Active Head Restraints During Backset Retention
Testing
The next issue is somewhat complex to explain. Certain head
restraints, known as ``mechanical active head restraints,'' move with
respect to the seat due to occupant loading. This means that these
systems move the head restraint forward and up by activation of a lever
mechanism in the seat back. While this helps to ensure proper head
restraint placement for human occupants, it can create a problem when
developing a static \6\ test. When the backset retention test \7\ is
performed, the seat back is loaded through a backpan.\8\ For mechanical
active head restraints, this loading activates the lever and pivots the
head restraint forward. This is followed by loading of the head
restraint through a head form, which tends to rotate the head restraint
rearward. Thus, the head restraint is placed in an unstable condition
and is no longer acting as a rigid body. Under such conditions, it
would be difficult to meet the backset displacement limits.\9\ To
address this testing problem, in the May 2007 final rule the agency
modified the test procedure to allow those kinds of head restraints to
be fixed in the unoccupied seat position for purposes of the test. This
solved the problem of testing active head restraints in a static
manner. For reference, the regulatory text (emphasis added) of 5.2.7(a)
states that for head restraints that move with respect to the seat when
occupant loading is applied to the seat back, S5.2.7(a)(1) through (8)
may be performed with the head restraint fixed in a position
corresponding to the position when the seat is unoccupied.
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\6\ Alternatively, manufacturers have the ability to certify to
a dynamic test requirement.
\7\ The backset retention test helps ensure that when the head
is forced back, as in a crash, the head restraint stays in position.
\8\ A backpan is the part of the manikin that rests on the seat
back.
\9\ To pass the backset retention test, the head form must not
move more than 25 mm during the application of the initial reference
load (S4.2.7(a)(1)), not be displaced more than 102 mm during
application of the peak load (S4.2.7(a)(3)), and return to within 13
mm of the initial reference position when unloaded to the reference
load level (S4.2.7(a)(3)).
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One petitioner, Kongsberg, made three separate requests with regard
to this particular requirement. First, it asked that the agency clarify
the fixation allowance by specifying that the fixation of the active
head restraint occur closest to the occupant loading and not closest to
the head restraint. It justified this by arguing that there will be
looseness throughout the active head restraint mechanism. Second, it
requested that NHTSA ``set a minimum level of `forward movement.' ''
Lastly, it requested that this fixation allowance be extended to
electronically triggered active head restraints in addition to those
activated by occupant loading (body triggered). It argued that to limit
the allowance to body-triggered systems is not providing a standardized
test for all technologies.
Specification of Fixation Point
Kongsberg's first request (part 6.1 of its submission) relates to
the specific nature of where a mechanical active head restraint should
be fixed for purposes of the static backset retention test. As
paragraph S5.2.7(a) currently states, the head restraint is ``fixed in
a position corresponding to the position when the seat is unoccupied.''
However, some mechanical active head restraints may have several
linkages that transfer occupant loading on the seat back into head
restraint movement. In that case, the petitioner stated, the regulatory
text as written would allow fixation at any of these points if it
ultimately restricts the head restraint from activation under seat back
loading.
Instead, Kongsberg requested that the agency change the regulatory
text to require that mechanical active head restraints be fixated at
the linkage point closest to the occupant loading. Doing otherwise, the
petitioner argued, would give an unfair advantage to mechanical active
head restraints, because they could be fixated at the point where the
head restraint connects to the seat back rather than where it first
feels the force of the occupant loading. If this were the case, then a
mechanical active head restraint could pass the retention test, even if
there was looseness in the head restraint-seat back connection, where a
different type of head restraint with the same strength characteristics
would not have passed.
Limiting the Fixation Option to Head Restraints That Have a Minimum
Level of Forward Movement
The next point from Kongsberg's petition (part 6.2) in this area is
its request that NHTSA set a minimum level of ``forward movement.''
While the precise request being made is not clear, it is effectively
asking NHTSA to functionally define how far an active mechanical head
restraint must be able to move forward in order to be classified as
such, and therefore, take advantage of the ability to be fixated during
static testing of head restraint displacement.
Expansion of Fixation Option to Reactive and Electronically-Triggered
Head Restraint Systems
Third, Kongsberg petitioned the agency (part 6.2.2 of its
submission) to expand the fixation option to include all reactive and
electronically triggered head restraints during static testing.
Currently, this option is only available for ``head restraints that
move with respect to the seat when occupant loading is applied to the
seat back,'' that is, for active mechanical head restraints. Kongsberg,
in the background section of its submission, defined two broad
categories of head restraints: ``reactive systems,'' in which energy
from body

[[Page 67238]]

mass is transferred to mitigate the impact of a head on a head
restraint; and ``proactive systems,'' in which stored energy is
released to mitigate the impact. The petitioner claimed that permitting
the fixation option for only active mechanical head restraints, is not
providing standardized testing of all technologies. For example,
electronically triggered head restraints also move during impact, but
do not qualify for the fixation option because they do not move with
respect to the seat in response to occupant loading. Kongsberg would
like NHTSA to permit all of these types of head restraint systems to be
fixed in position for purposes of static testing.
d. Clarifying Definition of Adjustable Head Restraints
Kongsberg made a request that the agency clarify the definition of
``adjustable head restraints.'' Specifically, Kongsberg requested that
they be defined ``in such a way that it is only possible to classify
into the `adjustable' category, head restraints which have no
adjustment locks, yet lock into just a single in use locking
position.'' It added that ``[t]his could be either a traditional head
restraint with separate cushion which has a one time lock into use
position or an advanced stowage mechanism which again has only a single
in use lock position.''\10\
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\10\ Kongsberg petition, 4.2.1.
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The stated purpose of this definition would be to clarify that the
types of head restraints described above could be classified as
``adjustable'' head restraints, thereby permitting them to use the 25
mm cylindrical gap test as per paragraph S4.2.4.2. The option to use
the 25 mm cylindrical gap test was added in the May 2007 final rule.
e. Technical Amendments
In addition to the substantive issues, several issues of technical
clarification and one issue of a clerical nature were brought to the
agency's attention.
2. Petitions for Rulemaking
a. Discomfort Metric for Non-Use Position and Relaxation Requirement
for Gap
Two petitioners, Mitsubishi and the Alliance, requested that the
agency do rulemaking, preferably on an expedited basis, on something
known as a ``discomfort metric.'' The discomfort metric is a mechanism,
adopted as part of the GTR for head restraint systems, for measuring
the level of discomfort imposed by a head restraint system in a non-use
position. This discomfort would, in theory, lead the occupant of the
seat to adjust the head restraint to an in-use position. The
petitioners requested that NHTSA incorporate the discomfort metric as
an additional rear head restraint non-use position compliance option in
paragraph S4.4. Additionally, Mitsubishi petitioned the agency to add a
relaxation requirement for the gap within the head restraint. This
relaxation requirement is also a part of the GTR, and Mitsubishi
requested that the agency do an ``expedited rulemaking'' to incorporate
both of these provisions.
b. ``Effective Backset''
Kongsberg requested that the agency replace its backset requirement
(of 55 mm) with an ``effective backset'' requirement (of 58.5 mm) when
a 10 N load is applied to the head restraint. According to the
petitioner, this additional 3.5 mm represents the amount of
displacement/compression one would expect from applying that reference
load. Backset, as described in paragraph S5.2.3, is the distance
between the rear of the head form and the front edge of the head
restraint. This is currently a simple measurement, and is taken without
applying force to the head restraint that would cause displacement.
The petitioner's concept of effective backset is that the backset
should be measured with a certain amount of force applied to the head
restraint. According to the petitioner, various features of the head
restraint, such as a layer of soft ``comfort foam'' on the outside, air
gaps within the restraint, or looseness in the connecting mechanisms
(if they exist), could displace with a small amount of force applied to
the head restraint. Therefore, according to Kongsberg, measuring the
backset with a small amount of force (sometimes called a ``reference
load'') on the head restraint provides a better indication of where the
head restraint will begin to apply significant resistance to a
rearward-moving head.
Kongsberg also requested that the agency adopt requirements for
rear seat effective backset as an alternative to its backset retention
requirements for rear seat head restraints. It requested a 58.5 mm
effective backset for rear seat head restraints with only one locking
position, and an 80 mm effective backset for rear seat head restraints
with multiple locking positions. While currently head restraints in
rear seats do not have backset requirements (that is, manufacturers can
choose a backset value for reasons of occupant comfort or other design
considerations),\11\ the head restraints are required to be able to
withstand substantial loads from wherever they are placed. In the first
part of the retention requirement, head restraints must displace no
more than 25 mm when a 37 Nm reference load is applied. The head
restraint is then loaded to 373 Nm (with a 102 mm displacement limit)
and finally unloaded to the reference value (where it must be within 13
mm of the reference position).
---------------------------------------------------------------------------

\11\ Most of the benefits of rear head restraints come from the
height, not the backset.
---------------------------------------------------------------------------

This, according to Kongsberg, results in head restraints with an
advanced stowage mechanism and only a single locking position, being
penalized. It similarly stated that head restraints with multiple
locking positions should have relief, as long as they stay within the
overall limit of the effective backset.

III. Agency Response to Petitions for Reconsideration of May 2007 Final
Rule and Technical Amendments

A. NHTSA Declines To Adopt a 5-Degree Torso Change Angle for Rear Seat
Non-Use Positions

With regard to non-use positions for rear seat head restraints,
NHTSA has provided a variety of options in FMVSS No. 202a.
Specifically, a manufacturer can choose one of four routes to comply
with the standard. It can:
(1) Use a removable head restraint.
(2) Have a non-use position that produces a 10-degree torso angle
change.
(3) Have a non-use position that rotates 60 degrees.
(4) Have a non-use position that automatically positions the head
restraint when the seat is occupied.
The Alliance's petition seeks to expand these options by modifying
the torso angle change option to create a torso angle change of
anywhere from 5 to 10 degrees. The basic rationale behind the
Alliance's petition is that the 10-degree torso change option is not
adequate to accommodate the popular feature of stowing rear seats in
the floor of a vehicle, and that a 5-degree option would be more
flexible. In its petition\12\, the Alliance stated:
---------------------------------------------------------------------------

\12\ Docket No. NHTSA-2007-27986-0012, p. 1.

[U]nfortunately, the approach taken in the final rule may not
provide the intended flexibility because it would require the
addition of material to shingled head restraints. In some vehicle
configurations this additional sizing would negate the ability to
stow seats and could potentially lead to unintended consequences to
children (in and out of child seats) and smaller occupants, such as
interference with tall child seats and

[[Page 67239]]

head/neck interference with small occupants. As a result, balancing
the tradeoffs associated with the additional option the Agency
sought to provide leads to an option that is not in fact a viable
---------------------------------------------------------------------------
option for some manufacturers.

NHTSA does not agree that permitting a 5-degree torso angle change
option is a necessary or appropriate change, nor do we believe that it
provides nearly as many safety benefits as the 10-degree option.
To begin, we will reiterate the rationale used in the 2007 final
rule to explain why NHTSA is limiting the torso angle change to 10
degrees. The torso angle change option is effective for the following
reasons: When the head restraint protrudes so far as to cause the
average occupant's torso to move forward by 10 degrees, the occupant
will feel discomfort and a physical cue that the head restraint is out
of position, and therefore adjust it so it functions properly. In its
human factors study,\13\ the agency found that a 5-degree torso angle
change does not cause occupants to realize that the head restraint is
in a non-use position, and therefore adjust it, nearly as often as a
10-degree torso angle change does. The study showed that while a 5-
degree change induced occupants to adjust the head restraint a mere 15
percent of the time, whereas a 10-degree change had the desired effect
80 percent of the time. As we stated in the 2007 final rule, it was the
results of this study that caused the agency to decline the
petitioner's request to permit a 5-degree torso angle change.
---------------------------------------------------------------------------

\13\ DOT HS 809 957, ``Rear Seat Stowable Head Restraint Non-Use
Position Torso Angle Study,'' November 2005.
---------------------------------------------------------------------------

In this new petition, the Alliance offered two arguments as to why
NHTSA should reconsider its reliance on the human factors study and
permit use of a 5-degree torso angle change option. First, it argued
that the NHTSA human factors study was limited to adults over 60
inches, and thus did not account for the fact that the majority of
occupants in rear seats are likely to be shorter (i.e., children).
Second, the Alliance stated that head restraints that use a 10-degree
torso angle change may interfere with the functioning of some child
seats. Additionally, the Alliance argued, as stated above, that some
vehicle designs may not be compatible with a head restraint that uses
the 10-degree torso angle change option. We will address these
arguments below. (We also note again that there are several other
alternative means of compliance.)
With regard to the human factors study, while NHTSA is aware that
it focused on adults, the agency does not consider that to be a defect
with the study. The Alliance pointed out that the occupants in the
study were at least 60 inches tall, whereas, according to National
Automotive Sampling System (NASS) General Estimates System (GES) data,
43 percent of crash-involved occupants of rear seats are under that
height. This should, according to the Alliance, ``lead to a conclusion
that the 10 degree torso angle displacement requirement, while
potentially preferable to force a response from taller adults, leads to
designs that are too stringent for children and child seats in certain
vehicle configurations.''
NHTSA does not believe that the fact that the human factors study
focused on adults over 60 inches impairs the relevance of that study,
nor did the Alliance present any data that this fact should cause NHTSA
to question to efficacy of the 10-degree torso angle change option.
With regard to the height of the occupants in the study, the reason
that NHTSA focused on taller occupants is that these are the only
occupants that benefit from rear seat head restraints. As stated in the
human factors study:

The height of rear seat passengers directly impacts where the
stowed head restraint would contact them. To determine how the
subject seat might interact with occupants of different heights, the
dimensions of the subject seat were measured. The seat dimensions
were considered along with standard sitting shoulder height values
for adult males and females to establish the range of occupant
heights that would be most likely to experience discomfort due to a
stowed head restraint. The standing height values used for
recruitment were established through extrapolation from the sitting
shoulder height values.
The height of the lower edge of the stowed head restraint in the
test vehicle is approximately 18.5 inches with respect to the seat
pan * * *. It appeared that an occupant whose sitting shoulder
height is approximately this value would not be uncomfortable with
the head restraint fully stowed. It was unclear how much greater
than 18.5 inches the threshold lies at which an occupant's sitting
shoulder height would be sufficiently large for the person to
experience discomfort.
The height at which children are no longer required to be seated
in a child safety seat is 57 inches. A 57-inch tall child (10-12 yrs
old) would have a sitting shoulder height of about 19.3 inches
(based on extrapolation from NIST data found on the Internet). Since
in its stowed position, the bottom of the head restraint is at 18.5
in, a 57-inch tall child may not be tall enough to experience
discomfort created by a stowed head restraint. Furthermore, children
of this age may not be mature enough to conclude that something is
wrong with the seat configuration if they experience only minor
discomfort. For this reason, as well as the difficulty in recruiting
minor subjects, participants less than 18 years of age were not
pursued.\14\
---------------------------------------------------------------------------

\14\ DOT HS 809 957, ``Rear Seat Stowable Head Restraint Non-Use
Position Torso Angle Study,'' November 2005, p. 13-15.

In summary, occupants less than 60 inches tall are unlikely to receive
any benefit from the torso angle change option, either because the head
restraint is too high to cause them discomfort, or because they are too
young to understand to adjust the head restraint if it is causing them
discomfort. On the other hand, the human factors study did show that,
for occupants tall enough to benefit from a head restraint (that is,
adults over 60 inches), a 5-degree angle change is insufficient to
cause them to adjust the head restraint to the use position, while a
---------------------------------------------------------------------------
10-degree change does have the desired effect.

We would further note that NHTSA did conduct at least one test
involving a 10-year old occupant using 5-, 10-, and 15-degree torso
angle change positions. The Alliance petition included the 10-degree
condition image from the report as an example of a child's head in what
they claimed was a non-preferred position. However, neither the human
factors study nor NHTSA has ever stated that subject had any negative
opinion about the 10-degree condition. Nor do we have any other
information that leads us to believe that short stature occupants such
as children in booster seats and older children without boosters would
have disaffection for the 10-degree condition. The petition did not
claim any data to this effect.
Second, the Alliance asserted that a 10-degree torso angle change
can interfere with certain child restraint systems (CRSs).
Specifically, it raised a concern about the potential inability to
secure a rigid forward-facing ISOFIX CRS to a seat that meets the 10-
degree torso angle change design. One potential problem it gave was
that ``the connection necessary for a rigid ISOFIX CRS anchorage may
not be possible in some vehicle configurations if the head restraint is
built to conform to a 10-degree torso angle displacement.''
Additionally, for occupants using high-back CRSs, the torso
displacement criteria would result in forward or rotational
displacement of the child seat. Finally, it stated that children in
backless booster seats or not seated in child restraint systems could
experience head and neck interference by head restraints designed to
the 10-degree torso angle change criteria.
There are several reasons why NHTSA does not consider this a valid
argument for permitting a 5-degree torso angle change option. The first
is, again,

[[Page 67240]]

that the NHTSA study indicated that a 5-degree change simply does not
cause a rear seat occupant to adjust an out-of-position head restraint.
Thus, a line of reason arguing that a 5-degree change could better
accommodate certain CRSs does not address the fundamental rationale for
disallowing a 5-degree option. Second, NHTSA is aware that contact
occurs between current non-regulated rear seat head restraint designs
with certain forward-facing CRSs, and typically adjusting the seat back
and/or head restraint can achieve proper CRS orientation. Sometimes,
depending on the design of the CRS, seat, and head restraint, it may be
necessary or easier to simply remove the head restraint to properly
install the CRS, which is one reason why NHTSA continues to allow head
restraint removal as an option (see 69 FR 74871). The mere fact that
one permissible non-use option may not work for all CRS/seat
configurations is not sufficient justification to allow a relatively
unsafe non-use position option. Finally, we do not believe that there
are currently any forward-facing ISOFIX CRSs on the market, thus their
potential lack of compatibility with a 10-degree design is of limited
significance.
The Alliance raised the issue of high-backed CRSs, as they are most
likely to contact the head restraint in the lowered, non-use position.
This is not new information, and was addressed in the 2004 Final Rule.
We believe that the statement in that rule is still appropriate:

With respect to comments pertaining to the potential
incompatibility between rear head restraints and some high-back
hybrid child restraints and boosters, NHTSA notes that high-back
child restraints are used in Europe with no reports of
incompatibilities. As Magna commented, rear seat head restraints are
much more common in Europe due to competitive pressures.
Nonetheless, if incompatibilities arise in this country, they can be
resolved by several means. First, we believe that an adjustable head
restraint is likely to have a position that does not interfere with
high back hybrid child restraints. That is, raising the head
restraint may alleviate the potential interference. Second, the
high-back child restraint can be installed in a seating position for
which a head restraint is not provided, removable, or has a non-use
position. We note that even where rear outboard head restraints are
provided, many vehicles do not provide a head restraint in the
center seating position. We recognize that, even with the
flexibility afforded to the manufacturers with respect to rear seat
head restraints, there may be isolated situations where certain high
back child restraints are not compatible with specific seating
positions in certain vehicles. However, we expect this to be
relatively infrequent. In short, the agency does not believe that
the possible incompatibilities are insurmountable even in situations
in which rear seats are equipped with optional head restraints.\15\
---------------------------------------------------------------------------

\15\ 69 FR 74847, 74871.
---------------------------------------------------------------------------

Because the petitioner did not provide new data regarding the safety
benefits of a 5-degree torso angle change design, or interference
between head restraints and CRSs, we are not adopting that option for
the rear seat head restraint non-use position.

B. NHTSA Declines To Permit Additional Leadtime for Small Vehicle
Manufacturers

In light of the fact that FMVSS No. 202a's head restraint
requirements are phased in over a period of several years, VSCI
petitioned the agency to permit small volume manufacturers (SVMs) to
wait until the end of the phase-in period to comply with the standard.
Its rationale is that while multiple-line manufacturers will only need
to convert a portion of their fleets to the new head restraint
requirements by the respective phase-in dates (September 1, 2009 for
front seat head restraints, and September 1, 2010 for rear seat head
restraints), a SVM with only one or two vehicle lines would need to
convert all of its vehicle lines to the new head restraint
requirements, while a large manufacturer with many lines would only
need to convert 80 percent of its vehicles. VSCI stated, ``[i]t would
not allow such SVMs the full amount of time that large manufacturers
have for redesign, testing, `implementing changes with the start of a
new model cycle,' and `additional flexibility in meeting these
challenges.' '' \16\ Therefore, according to the petitioner, SVMs are
particularly burdened by this rulemaking. We note that this argument is
not specific to the head restraints at issue, but in fact could be
applied to virtually any requirement with a phase-in period.
---------------------------------------------------------------------------

\16\ VSCI petition, Docket No. NHTSA-2007-27986-0010.
---------------------------------------------------------------------------

NHTSA declines to adopt this general argument. We note that the
burden of designing new head restraints to meet the requirements of the
upgraded FMVSS No. 202a is likely to be more for larger manufacturers,
as they will have to design compliant head restraints for a larger
number of vehicles, whereas SVMs, even if by the nature of their
product lines are required to bring all of their vehicles into
compliance at the start of the phase-in period, will only have to
design compliant head restraints for a small number of vehicle lines.
More importantly, we do not agree with the inherent logic of the
argument that SVMs should be permitted, generally, to delay any
compliance until the end of the phase-in periods for new requirements.
VSCI stated that over the past seven years, the agency has on numerous
occasions permitted SVMs to delay compliance until the end of the
phase-in periods. However, in previous rulemakings where NHTSA has done
this, it has given specific reasons--related to the standard at issue--
for permitting additional leadtime for SVMs. For example, in the 2000
FMVSS No. 208 final rule, we stated that SVMs do not have the access to
new technology at the same time as larger manufacturers.\17\ With
regard to advanced air bags, the subject of that rulemaking, there were
specific issues of a complex upgrade and short leadtime. Thus, there
were specific reasons for excluding SVMs from compliance with the
standard until they had been given more time to prepare. With regard to
the head restraint requirements of FMVSS No. 202a, however, we do not
believe this to be the case. There has already been substantial
leadtime since publication of the 2004 Final Rule and the 2007 Final
Rule in response to petitions for reconsideration. Furthermore, the
technologies required to comply with FMVSS No. 202a are not
particularly complex or novel. For those reasons, we decline to grant
additional leadtime to SVMs. Since we are not granting additional
leadtime to SVMs, VSCI's request that we adopt its definition of a SVM
is moot.
---------------------------------------------------------------------------

\17\ 65 FR 30720.
---------------------------------------------------------------------------

C. Static Lockout of Active Head Restraints During Backset Retention
Testing

As currently specified in paragraph S5.2.7(a), mechanical active
head restraints (that is, head restraints that move with respect to the
load on the seat) are fixed in their undeployed position for static
testing purposes. NHTSA modified the backset retention test procedure
(S5.2.7(a)) in the 2007 final rule by allowing mechanical active head
restraints the option of being fixed in position during the test. This
was done in response to several petitions requesting that the agency
allow more displacement for these types of head restraints, as they
were unable to meet the 25 mm requirement due to their active design.
Instead of granting additional leeway for displacement, however, NHTSA
instead included a provision permitting mechanical active head
restraints to be fixed in position. As we stated:

We note that the agency anticipated that there may be advanced
designs which, by their active nature, are unable to pass the

[[Page 67241]]

static test requirements in their undeployed positions. This is why
the dynamic compliance option was provided.
However, while the dynamic compliance option is specifically in
place for active systems, it has never been our intention to exclude
active systems from certifying through the static option. However,
the agency has emphasized that such static compliance must be in the
undeployed condition.

Based on our desire to not exclude the possibility of active
systems being certified to the static option, we have decided to permit
active systems to be fixed in their undeployed position during the
retention tests. We are including a specific manufacturer option to
this effect in FMVSS No. 202a.\18\
---------------------------------------------------------------------------

\18\ 72 FR 25484, 25504.
---------------------------------------------------------------------------

As discussed above, Kongsberg petitioned for a variety of
clarifications and amendments with regard to static testing of active
head restraints for purposes of the backset retention test. The company
asked the agency to specify exactly where the head restraint should be
fixed, assuming there are multiple locations in the deployment
mechanism it can be fixed at. Kongsberg also asked NHTSA to give
guidance as to how far forward a head restraint must be able to move
before it can be qualified as an active head restraint. Finally, the
company also asked NHTSA to expand this option beyond mechanical active
head restraints, to include what it refers to as ``reactive'' head
restraints as well as to those that are electronically-triggered. Our
responses to each of these three requests are set forth below.
1. NHTSA Agrees To Specify the Fixation Point for Static Testing of
Active Mechanical Head Restraints
In part 6.1 of its petition, Kongsberg makes the following
statement:

Within advanced head restraint systems, there will always be
freeplay within the moving parts resulting in system looseness.
Kongsberg requests that NHTSA clarify the test procedure in such a
way that specifies the procedure for fixating the head restraint.
That is fixation of the advanced mechanism should occur closest to
the occupant loading and not closest to the head restraint.

NHTSA believes that Kongsberg's request to specify the fixation
point has merit. For a mechanical active head restraint, there is a
mechanism that translates pressure on the seat back (caused by the body
being pressed back into the seat, such as during a rear impact) into
forward movement on the head restraint, to protect against whiplash. As
Kongsberg pointed out, a mechanical active head restraint may have
multiple linkages. For example, there may be one linkage where the seat
back connects to the head restraint, and another that moves when the
occupant's back presses into the front surface of the seat back. These
components could be connected directly or be connected through
intermediate linkages. As the specification is currently written, the
regulatory text would allow fixation at any of these linkage points, so
long as doing so prevents the head restraint from moving forward when
pressure is applied to the seat back. Kongsberg requests that NHTSA
clarify this ambiguity by specifying that the fixation must occur at
the point closest to the point where the force from an occupant's torso
would activate the head restraint.
We agree with Kongsberg's request for two reasons. First, the
request helps to resolve an ambiguity in the requirement--given
multiple locations where a head restraint could be fixed in a static
position, it provides clarity for NHTSA to specify which one is used.
Second, having the fixation requirement located at the spot closest to
the occupant's torso loading helps to prevent a situation where a
mechanical active head restraint could be less effective than another
type of head restraint. This would occur if a test fixed the head
restraint at the point where the seat back connects to the head
restraint, instead of another location closer to where occupant loading
occurs. In this situation, the test would not account for looseness in
the linkage between the head restraint and the seat back--a problem
that would have been uncovered if a different type of head restraint
had been used where no fixation was necessary to undertake a static
test. This would result in the head restraint passing the test when
force is applied to the seat back, but still moving too far when in
use, and an occupant strikes the head restraint.
For these reasons, we are revising S5.2.7(a) to provide that the
fixation is applied to the member(s) that first transmit(s) the seat
back loading from the occupant to the head restraint.
2. NHTSA Declines To Specify a Minimum Forward Movement Requirement for
Static Testing of Active Mechanical Head Restraints
Kongsberg also requested that ``NHTSA set a minimum level of
`forward movement' to clarify this new rule.'' \19\ This request is
effectively asking NHTSA to functionally define how far an active
mechanical head restraint must be able to move forward in order to be
classified as such, and therefore, take advantage of the ability to be
fixated during static testing of head restraint displacement.
---------------------------------------------------------------------------

\19\ Kongsberg petition, part 6.2.1.
---------------------------------------------------------------------------

After considering this request, we have decided not to define a
minimum forward movement criterion for active head restraints. We
believe the limitation in the regulatory text that this option is
available only for ``head restraints that move with respect to the seat
when occupant loading is applied to the seat back'' excludes typical
adjustable head restraints. The agency does not believe there is
ambiguity on that issue, and therefore believes that there is not a
problem that needs to be addressed. Second, we do not have any data on
what, if any, lower limit to place on the movement of a mechanical
active head restraint, nor did the petitioner supply any data or offer
a suggestion. Given these factors, we are not proceeding on this
request.
3. NHTSA Declines To Expand the Fixation Option to ``Reactive'' and
Electronically Triggered Head Restraints
The third request that Kongsberg put forth (in part 6.2.2 of its
petition) was to expand the fixation option from mechanical active head
restraints to all ``reactive'' and ``proactive'' head restraints.
Kongsberg defines these terms in the background section (part 1.0 of
its petition). Reactive head restraints, according to the petitioner,
are those where energy from body mass is transferred to the head
restraint to mitigate the impact. Proactive head restraints, on the
other hand, are those where stored energy is released to mitigate the
impact of the head on the restraint. Generally, proactive head
restraints would be electronically triggered at the time of a crash.
Kongsberg's request is that vehicle manufacturers be permitted to
certify all head restraints that move with respect to the seat back
through a static test with the head restraint in a fixed position, as
they can do with mechanical active head restraints. It claimed that
this would put all reactive and proactive head restraints in the same
position, and that not allowing this is creating special rules for one
segment of technology.
NHTSA declines to adopt Kongsberg's request and disagrees with its
reasoning on this point. The rationale for permitting the fixation
option for mechanical active head restraints, as explained in the 2007
rule, is not applicable to the other types of head restraints that
Kongsberg described. The fixation option was created because mechanical
active head restraints move relative to the seat back when the

[[Page 67242]]

backpan, simulating the back of an occupant, applies a load to it.
Therefore, they would almost certainly fail the initial backset
displacement test. Using the fixation option solves this limited
problem, allowing mechanical active head restraints to be tested in the
static test like all other head restraints. Electronically-triggered
``proactive'' head restraints, on the other hand, do not move when the
backpan applies a load to the seat back. Therefore, there is no need
for fixation.

D. ``Adjustable'' Head Restraints and Availability of 25 mm Cylindrical
Gap Test Option

As indicated above, Kongsberg made a request that the agency
clarify the definition of ``adjustable head restraints.'' Specifically,
Kongsberg requested that they be defined ``in such a way that it is
only possible to classify into the `adjustable' category, head
restraints which have no adjustment locks, yet lock into just a single
in use locking position.'' It added that ``[t]his could be either a
traditional head restraint with separate cushion which has a one time
lock into use position or an advanced stowage mechanism which again has
only a single in use lock position.'' \20\
---------------------------------------------------------------------------

\20\ Kongsberg petition, 4.2.1.
---------------------------------------------------------------------------

Vehicle manufacturers currently use three types of head
restraints to meet the requirements of FMVSS No. 202. The first type
is the ``integral head restraint,'' which is non-adjustable and is
built into the seat. It typically consists of a seat back that
extends high enough to meet the height requirement of the standard.
The second type is the ``adjustable'' head restraint, which consists
of a separate cushion that is attached to the seat back, typically
by two sliding metal shafts. Adjustable head restraints typically
adjust vertically to accommodate different occupant seating heights.
Some also provide adjustments to allow the head restraint to be
moved closer to the occupant's head. The third type is the active
head restraint system, which deploys in the event of a collision to
minimize the potential for whiplash. During the normal vehicle
operation, the active head restraint system is retracted.\21\
---------------------------------------------------------------------------

\21\ 72 FR 25484, 25484-5.

We did not include definitions in the regulatory text because
distinctions between the types of head restraints are not typically
necessary. In general, the performance requirements of FMVSS No. 202a
are applicable for all types of head restraints and adjustable head
restraints are specifically referenced to indicate the ``adjusted''
position they are to be configured in for testing. This is also the
case in S4.2.4.1 and S4.2.4.2, which indicate that adjustable head
restraints are to be placed in their lowest height position and any
backset position.
However, a unique feature of S4.2.4 is that it states that the
requirement for gaps between the seat and head restraint is limited to
adjustable head restraints. Although a definition of adjustable head
restraint is not included in the standard, the agency addressed the
meaning of the term in a March 29, 2009 letter of interpretation to
Kongsberg. In that interpretation, we concluded that a folding head
restraint that only has a single in-use position, regardless of
movement to non-use positions, would not be considered an adjustable
head restraint. Therefore, the types of head restraints that Kongsberg
described in their petition would not have the option of using the
procedure in paragraph S4.2.4.2 to determine the acceptability of the
gap between the seat and the head restraint.
For the reasons explained below, we are revising FMVSS No. 202a in
a way that will accommodate Kongsberg's concern, but not by defining
the head restraints at issue as adjustable head restraints.
In analyzing the Kongsberg petition, we have considered the
rationale provided in the May 2007 final rule for providing this gap
measurement alternative. In a section of the preamble to the 2007 final
rule discussing the gap between the head restraint and seat back we
stated the following: \22\
---------------------------------------------------------------------------

\22\ 72 FR 25503.

After considering the DaimlerChrysler and Alliance petitions, we
have decided to specify that the gap requirement must be met when
the gap is measured either by the existing current FMVSS No. 202a
procedure using a sphere or one based on the ECE 17 measurement
methodology. We are not aware of any data showing benefits to one
---------------------------------------------------------------------------
methodology over the other.

The agency did not provide a specific explanation of why the option
was limited to adjustable head restraints. We note that Appendix G of
the DaimlerChrysler petition stated the following:

S5.7 of ECE R17 requires a maximum gap of 60 mm for head
restraints which are not adjustable, and a maximum gap of 25 mm for
adjustable systems in the lowest position. The gap is measured
similar to the height of the head restraint, perpendicular to the
torso line as illustrated below.

Consequently, the limitation of S4.2.4 to adjustable head
restraints was consistent with the petitioner's request. However, the
specific types of design for which DaimlerChrysler mentioned in its
request for the additional compliance option were ``shingled'' and
``saddle'' designs. Such designs used for rear seats could have a
single in-use position of height adjustment. Thus, the 25 mm cylinder
option currently would not be available to such a design.
Given Kongsberg's petition, we considered whether there is a good
reason to exclude from this option head restraints that lock in a
single in-use position. In analyzing this question, we looked at two
similar theoretical rear seat head restraint designs. The first was a
shingle head restraint that could move from a non-use position to a
single in-use position. The second design could move from a non-use
position to a lowest in-use position of adjustment, but also had
several other in-use adjustment positions. However, in the lowest
adjustment position, it occupied the same position in space as the
first design that only had one in-use adjustment position. Thus, in the
position of adjustment in which the gap measurement test would be
performed, there would be no functional difference between the two
designs. Given this, we believe that there is not a safety reason to
exclude from this option head

[[Page 67243]]

restraints that lock in a single in-use position.
In light of the above, we have decided to revise the regulatory
text so that the 25 mm cylinder option is available for all head
restraints that can move with respect to the seat. This will make this
option available for the types of designs described by Kongsberg. The
revisions are in S4.2.4.2.
We note that we do not believe it would be appropriate to extend
the 25 mm cylinder option to integral head restraints. In the 2004
final rule, the agency specified that the gap measurement was to be
made 540 mm above the H-point ``[b]ecause there may not be a clear
distinction between the end of the seat back and the beginning of the
head restraint in integral head restraints.'' \23\ This fact would make
it difficult to apply the 25 mm cylinder option to integral head
restraints because it may not be possible to determine where the gap
between the head restraint and seat back is. Therefore, there is reason
to exclude integral head restraints from this option.
---------------------------------------------------------------------------

\23\ 69 FR 74862.
---------------------------------------------------------------------------

Finally, we note that the above analysis made no distinction
between head restraints that move through some action of the occupant
or active head restraints that might only move in a rear impact. The
reason for this is that we do not believe there will be any ambiguity
in finding the gap between the head restraint and seat back in these
designs and thus using the 25 mm cylinder option.

E. Technical Amendments and Corrections

In addition to petitions for reconsideration and rulemaking, the
agency also received a petition from the Alliance requesting that
several minor technical corrections be made to the regulatory text of
FMVSS No. 202a. Additionally, one part of Kongsberg's petition was not
considered a petition for reconsideration, but the suggested change
represented a technical correction. The issues raised by these
petitions are addressed below. In addition, NHTSA identified an error
in which regulatory text was inadvertently removed by the 2007 final
rule.
1. NHTSA Agrees To Revise S5.2.4.2. The first change to the
standard requested by the Alliance was in regard to paragraph S5.2.4.2.
This section describes the ``gap test,'' used to determine if the
distance between the seat back and the head restraint is acceptably
small. According to S4.2.4.2, the maximum gap permitted is 25 mm.
Paragraph (c) of the procedure (S5.2.4.2(c)) reads ``Determine if at
least 125 mm of the [25 mm diameter] cylinder can completely pass
through the gap.'' If testing shows that 125 mm or more of the cylinder
can pass through the gap between the seat back and the head restraint,
the head restraint would fail the test.
The Alliance petitioned that the language in paragraph (c) be
changed from the current wording to read ``Determine that no more than
125 mm of the cylinder can completely pass through the gap.'' It
requested this language for purposes of clarification.
While we are not adopting the language suggested by the Alliance,
we are adding a sentence to clarify that if 125 mm or more of the
cylinder can pass through the gap, the head restraint would fail the
test.
2. NHTSA Agrees To Revise S5.3.4. The Alliance's second requested
change involves the reordering of two of the sentences in the dynamic
performance test description in paragraph S5.3.4. Section S5.3.4
specifies the seat adjustment requirements for the dynamic compliance
option.
The effect of moving the two sentences at issue from the beginning
of the setup procedure to the suggested locations would be, according
to the petition, to change the sequence of steps in which the
laboratory sets up the seat for the dynamic test. Instead of setting
the inclination of the seat back at the beginning of the process, the
laboratory would make the final seat back adjustment after the vertical
and fore-aft adjustments are set.
According to the Alliance, the purpose of the requested change is
to reduce test-to-test variability of the dynamic test. It stated that
setting the seat back adjustment at the beginning of the setup process
can lead to some variability, and that it is general laboratory
practice ``to locate the seat cushion position first and make the final
seat back adjustment after the vertical and fore-aft adjustments are
set.'' \24\ Reordering the regulatory text in that manner would
facilitate testing, according to the petitioner.
---------------------------------------------------------------------------

\24\ Alliance petition, Docket No. NHTSA-2007-27986-0013, p. 2.
---------------------------------------------------------------------------

After considering the Alliance's petition, we provide the following
response. We did not intend in the 2007 final rule to specify a
``sequence'' of seat adjustment in S5.3.4. Our intent was to specify
conditions to be met concurrently when the seat is in its final state
of adjustment, in consideration of the various modes to achieve those
conditions. We believe the specified adjustments can exist in harmony
with each other. For example, S5.3.4 provides, through reference to S5,
that the seat cushion and seat back must be adjusted such that the
final H-point position is the highest H-point position with respect to
the seat back.\25\ However, this adjustment must be done in the context
of achieving a final 25 degree seat back inclination. Achieving this H-
point position with the correct seat back angle may involve an
iterative process of adjusting various seat positioning controls. It
would therefore not be correct to consider S5.3.4 as specifying a
sequence of adjustments. Moreover, given the current language of the
section and as indicated by the petitioner, there would not be a
control on the final seat back angle.
---------------------------------------------------------------------------

\25\ This provision effectively minimizes the measured seat
height.
---------------------------------------------------------------------------

To clarify this, we are adding a sentence to S5.3.4 stating that
the specified seat adjustments are a list of conditions. We are also
moving the two sentences as requested by the petitioner, but note that
this will not affect the requirements of the standard. In light of the
petitioner's misunderstanding about the issue of seat adjustment we are
also adding a sentence to S5 to clarify that the seat adjustments made
in S5 and S5.1 are also a set of conditions rather than a sequence.
Again, we believe that adding clarification here will have no effect on
the standard.
In S5.3.4, we are also removing a reference to S5.1 which is
outdated.
3. NHTSA Agrees To Revise S5.2.6(d) and S5.2.7(a)(7). The third
requested technical amendment relates to the testing of height
retention (S5.2.6) and backset retention (S5.2.7(a)). In the 2007 final
rule, NHTSA introduced a ``zero load'' condition into these tests.
Essentially, this is a pause between when the largest amount of force
is applied and the final test load is applied, to reduce hysteresis in
the foam of the head restraint. In those sections, NHTSA specified that
the zero load condition should be maintained for not more than two
minutes.
The Alliance requested that instead of specifying ``not more than
two minutes,'' NHTSA specify that the zero load condition be maintained
for ``two minutes, +/-5 seconds.'' It stated that this change would
provide more clarity for the test procedure. We agree with their
argument. We believe it will clarify our original intent and reduce any
potential variability. This change will be reflected in the regulatory
text of the two paragraphs.
4. NHTSA Agrees To Revise S5.2.7(a)(5). The portion of the
Kongsberg petition on the load vector

[[Page 67244]]

position in the backset retention test \26\ is not related to any
change made to the 2004 final rule by the 2007 final rule. Therefore,
it is not a petition for reconsideration. However, NHTSA has determined
that the requested clarification would constitute a technical
amendment. Therefore, we are addressing it in this document.
---------------------------------------------------------------------------

\26\ Kongsberg petition, part 5.0.
---------------------------------------------------------------------------

Kongsberg requested that the agency clarify the test procedure in
such a way that specifies that the load vector is applied through the
centerline of the head form at a height 65 mm +[sol]- 3 mm below the
top of the head restraint.
NHTSA believes that the Kongsberg interpretation of the test
procedure specified in S5.2.7 of FMVSS No. 202a is correct. In fact,
this test is derived from paragraph S5.2 of the version of FMVSS No.
202 now in force, which allows for the use of a cylinder to apply the
required force. When a cylinder is used to apply the force, because of
the shape or angle of the head restraint, it may not make it possible
to assure the point of contact is 65 mm below the top of the head
restraint or to do so may result in a position of the axis of load
application far from the 65 mm position. However, the axis of load
application can be controlled. Although paragraph S5.2.7 of FMVSS No.
202 specifies a spherical head form loading device, the concept of
aligning the axis of load application, represented by the centerline of
the head form, remains the same (see Figure 1). Thus, we believe any
clarification is simply a technical correction of the existing
regulatory text. We are therefore revising S5.2.7(a)(5) to provide this
clarification.
We note that the configuration in the illustration is for
explanatory purposes only. Other configurations are acceptable if they
conform to the text of the standard.
[GRAPHIC] [TIFF OMITTED] TR02NO10.011

5. NHTSA Is Correcting Clerical Errors in S4.3 and S5.3. The 2004
final rule altered the head restraint position specification for the
dynamic compliance option from any position of adjustment to a mid-
height position and any position of backset adjustment.\27\ This was
indicated in both paragraphs S4.3 and S5.3. However, the 2007 final
rule inadvertently removed the phrase ``and at any position of backset
adjustment'' from the regulatory text in each of those sections. In
this document, we are correcting that clerical error by modifying S4.3
and S5.3 to be consistent with the provisions for backset adjustment
previously specified in the 2004 final rule.
---------------------------------------------------------------------------

\27\ 70 FR 74886 and 74888.
---------------------------------------------------------------------------

IV. Agency Response to Petitions for Rulemaking

A. NHTSA Declines To Conduct Rulemaking Concerning Discomfort Metric or
Relaxation Requirement for Gap Separate From the Rulemaking Based on
the GTR

The Alliance and Mitsubishi Motors petitioned NHTSA to perform
``expedited rulemaking'' to permit an additional option for certifying
compliance for a rear seat non-use position, something known as the
``discomfort metric.'' The discomfort metric is, briefly, a measurement
of the location of the head restraint with respect to the position of
the occupant of the vehicle.
According to Mitsubishi, the discomfort metric, using certain
values provided by the Japanese Automotive Manufacturers Association,
is effective in prompting the seated occupants to adjust the head
restraint from a non-use position to an in-use position.

[[Page 67245]]

Mitsubishi also petitioned the agency to add a relaxation requirement
for the gap within the head restraint. Mitsubishi stated that these
provisions are both parts of the new GTR for head restraints.
NHTSA notes that the GTR on head restraints was adopted in March
2008. The GTR incorporates NHTSA's backset requirement, as well as
offering a means to harmonize the remaining differences between the
FMVSS and UNECE standards.\28\ However, in order to modify the FMVSSs,
NHTSA must propose to adopt the provisions in the GTR.
---------------------------------------------------------------------------

\28\ See 73 FR 8743, February 14, 2008.
---------------------------------------------------------------------------

NHTSA is in the process of preparing an NPRM regarding the GTR
provisions. However, we decline to conduct a separate rulemaking
concerning a specific subset of the GTR provisions. There are a variety
of interrelationships between the various requirements and related test
procedures in any GTR, including the one on head restraints. The agency
therefore believes it is important to consider the various provisions
of a GTR together in a single rulemaking.

B. NHTSA Denies Petition for Rulemaking To Replace the Current Backset
Requirement With an ``Effective Backset'' Requirement

Paragraph S5.2.3 of FMVSS No. 202a specifies a 55 mm backset limit.
Backset is measured using a Head Restraint Measurement Device (HRMD),
consisting of a specified head form attached to the Society of
Automotive Engineers (SAE) J826 manikin (rev. Jul 95). The head form
includes a probe that slides rearward until contact is made with the
head restraint. The resulting measurement reflects the horizontal
distance between the back of the head of a seated 50th percentile adult
male dummy and the front of the head restraint.
Kongsberg requested (in part 2.5 of its petition) that this 55 mm
limit be replaced with a 58.5 mm ``effective backset'' specification,
which would be measured in a different way. Under the method
recommended by the petitioner, a 10 N force would be applied as a
preload. The 58.5 mm figure recommended by the petitioner is derived
from adding the backset and a 3.5 mm displacement to represent the
typical net effect of additional system flex when a 10 N preload is
applied.
Kongsberg argued that a test method that only measures static
backset is inferior to dynamic methods. It believes that its
recommended method of measuring backset would improve the correlation
between the static and dynamic measurements. According to Kongsberg,
the preload application serves to improve this correlation by
considering the effect of: (i) Very soft foam; (ii) the air gap between
upholstery and foam; and (iii) the flex within the adjustment
mechanism. As for the 10 N and 3.5 mm figures specifically, Kongsberg
stated that the GTR was, at the time of Kongsberg's petition, reviewing
the application of a 10 N preload to ``prevent very soft head
restraints'' and reported a typical net effect of 3.5 mm additional
system flex. We note that while the working group did review a
presentation suggesting this approach, it was ultimately rejected in
favor of the current procedure.
Kongsberg also argued that the agency recognized the benefit of
using a pre-load in the gap measurement test procedure, and that this
benefit should be extended to all tests that have the goal of measuring
the position of foam and trim.
While we have considered the arguments raised by Kongsberg, we have
decided to deny its petition in this area.
First, we believe that the petitioner has not demonstrated that its
recommended approach would result in significant safety benefits or any
other need for the approach. The agency's estimate of backset benefits
is based on the current measurement method and, as such, takes into
account physical factors associated with current head restraints that
are related to system flex. To the extent the petitioner's
recommendation would increase the backset limit by the amount that is
the typical net effect of additional flex associated with a 10 N pre-
load, it would not be expected to result in significant safety
benefits. While the approach recommended by Kongsberg might be used to
address possible concerns about very soft head restraints or ones that
had excessive flex, the petitioner has not demonstrated that this
possible problem is sufficiently large to warrant rulemaking. Moreover,
the approach recommended by the petitioner could result in a less
stringent requirement for some head restraints. The petitioner has not
demonstrated a need for increased flexibility.
Also, there would be additional costs and complexity associated
with the effective backset method. Unlike the current backset
measurement method, the recommended effective backset method would
require load measurement capability. The current HRMD backset probe
does not have that capability, and adding such a capability is not
necessarily a simple matter. Furthermore, this adjustment would require
additional assessment of the procedure.
As to the gap measurement using a 165 mm sphere, both the 2004 and
2007 final rules specified that no more than a 5 N load is applied to
the sphere when performing the measurements. This measurement relies on
the ability to clearly delineate the points/lines of contact between
the 165 mm sphere and the head restraint, and is thus a more complex
measurement. In the laboratory, this is typically achieved through
transfer paint applied to the head restraint. As a practical matter,
the same device is used to perform this test as the backset retention
test, and the ability to measure applied load is built into the
apparatus.
We also note that the agency has explained and justified the
current requirement in previous documents in this rulemaking, and
previously addressed issues related to effective backset.
Given the lack of apparent safety benefits, lack of demonstrated
need for a changed approach, and the additional testing and evaluation
and other resources that would be needed for the agency to further
consider rulemaking in this area, we deny this part of Kongsberg's
petition.

C. NHTSA Denies Petition for Rulemaking To Adopt Effective Backset
Requirements for Rear Head Restraints as Alternative to Backset
Retention Requirement

Kongsberg petitioned the agency to adopt requirements for rear seat
head restraint effective backset as an alternative to the backset
retention requirement. It requested a 58.5 mm effective backset for
rear seat head restraints with only one locking position, and an 80 mm
effective backset for rear seat head restraints with multiple locking
positions. Kongsberg did not expressly state what procedure should be
used for the 80 mm effective backset, but the implication is that it
would be through application of a load through the backset probe
equivalent to 37 Nm.
FMVSS No. 202a does not specify backset requirements for rear seat
head restraints, and those restraints themselves are not required.
However, rear head restraints are subject to the backset retention
requirements in S4.2.7. This is to ensure that the head restraint, if
provided, is capable of providing the requisite strength to prevent
whiplash.
Kongsberg indicated that it does not believe the agency has
considered the effect of complex stowage and adjustment mechanisms in
the rear seats

[[Page 67246]]

where there is not a backset requirement. It claimed that because of
the amount of movement that can come from ``comfort foam'' compression,
the current requirement is not a test of the head restraint lock. The
petitioner stated that ``[a]dvanced stowage mechanisms are penalized in
a way that requires new head restraint solutions (with no comfort foam)
even though the effective backset (sum of the measured backset and foam
preload) is comparable to the NHTSA backset requirement for front row
and is also below the value required of a front seat IIHS static good
rating.'' It stated that if the advanced stowage systems have
adjustments that allow multiple lock positions, ``these solutions
should have relief from the backset retention requirements if the
`effective' backset measurement, in all adjustment positions, is
comparable to the strict backset requirements for front row.''
We begin by noting that Kongsberg stated in its petition that it
``proposes'' that a more meaningful test for backset retention in rear
seating applications would be ``one that provides an alternative to
certify with an effective backset * * *.'' Given this language, the
petitioner appears to be requesting a manufacturer option in this area
rather than that the agency necessarily establish a mandatory backset
requirement for rear head restraints.
We note that the agency proposed to limit rear seat head restraint
backset in the 2001 NPRM (66 FR 968), which also would have required
that rear seat head restraints be provided. However, for the reasons
explained in the 2004 final rule preamble, we decided not to require
rear seat head restraints and eliminated the backset limit for
optionally provided rear seat head restraints (69 FR 74857). Kongsberg
did not address the reasons provided by the agency in that decision or
provide an analysis demonstrating a need for a mandatory backset
requirement for voluntarily-provided rear head restraints, and we are
not revisiting that issue at this time.
After considering the arguments raised by Kongsberg, we have
decided to deny its petition in this area. On the issue of relief from
the backset retention requirement for rear head restraints, we do not
believe such relief is in the interest of safety. Although there is no
backset requirement for voluntarily-provided rear seat head restraints
and the height requirement is less stringent, the agency believes that
it is important for these head restraints to maintain their adjusted
position just as it is for required front seat head restraints. NHTSA
believes that when a vehicle occupant adjusts the backset of a head
restraint to the proper position, it should maintain its adjusted
position in the event of a collision. This is also consistent with our
position that front seat head restraints must meet the backset
retention test even in adjustment positions with less backset than 55
mm. While we have considered the arguments and data provided by
Kongsberg, including data subject to a request for confidentiality, the
petitioner has not demonstrated that there is a practicability problem
with the backset retention test.
Neither has the petition demonstrated why the agency should apply
one effective backset requirement to head restraints with a single
locking position (58.5 mm at 10 N) and another effective backset
requirement to head restraints with multiple locking positions (80 mm
at 37 Nm).
We also note that the agency has explained and justified the
current requirement in previous documents in this rulemaking, and
previously addressed issues related to effective backset.
For the reasons discussed above, we deny Kongsberg's petition in
this area.

V. Rulemaking Analyses and Notices

This rule makes several minor changes to the regulatory text of
FMVSS No. 202a, and does not increase the regulatory burden on
manufacturers. The agency has discussed the relevant requirements of
the Vehicle Safety Act, Executive Order 12866, the Department of
Transportation's regulatory policies and procedures, the Regulatory
Flexibility Act, Executive Order 13132 (Federalism), Executive Order
12988 (Civil Justice Reform), Executive Order 13045 (Protection of
Children from Environmental Health and Safety Risks), the Paperwork
Reduction Act, the National Technology Transfer and Advancement Act,
the Unfunded Mandates Reform Act, and the National Environmental Policy
Act in the May 2007 final rule cited above. Those discussions are not
affected by these changes.

Privacy Act

Please note that any one is able to search the electronic form of
all documents received into any of our dockets by the name of the
individual submitting the document (or signing the document, if
submitted on behalf of an association, business, labor union, etc.).
You may review DOT's complete Privacy Act Statement in the Federal
Register published on April 11, 2000 (Volume 65, Number 70; Pages
19477-78), or you may visit http://www.dot.gov/privacy.html.

Revised Regulatory Text

List of Subjects in 49 CFR Part 571

Imports, Motor vehicle safety, Reports and recordkeeping
requirements, Tires.

0
In consideration of the foregoing, NHTSA is amending 49 CFR part 571 as
follows:

PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS

0
1. The authority citation for part 571 continues to read as follows:

Authority: 49 U.S.C. 322, 30111, 30115, 30117, and 30166;
delegation of authority at 49 CFR 1.50.

0
2. In Sec. 571.202a, revise S4.2.4.2, S4.3, S5, S5.2.4.2(c),
S5.2.6(d), S5.2.7(a) introductory text, S5.2.7(a)(5), S5.2.7(a)(7),
S5.3, and S5.3.4 to read as follows:

Sec. 571.202a Standard No. 202a; Head restraints; Mandatory
applicability begins on September 1, 2009.

* * * * *
S4.2.4.2 Gaps between the head restraint and seat using a 25 mm
cylinder. The following option is only available to head restraints
that can move with respect to the seat. When measured in accordance
with S5.2.4.2 of this section using the 25 mm cylinder specified in
that paragraph, there must not be any gap greater than 25 mm between
the anterior surface of the head restraint and anterior surface of the
seat, with the head restraint adjusted to its lowest height position
and any backset position, except as allowed by S4.4.
* * * * *
S4.3 Dynamic performance and width. At each forward-facing outboard
designated seating position equipped with a head restraint, the head
restraint adjusted midway between the lowest and the highest position
of adjustment, and at any position of backset adjustment, must conform
to the following:
* * * * *
S5 Procedures. Demonstrate compliance with S4.2 through S4.4 of
this section as follows. The positions of seat adjustment specified in
S5 and S5.1 are conditions to be met concurrently and are not a
sequential list of adjustments. Any adjustable lumbar support is
adjusted to its most posterior nominal design position. If the seat
cushion adjusts independently of the seat back, position the seat
cushion such that the highest H-point position is achieved with respect
to the seat back, as measured by SAE J826 (July 1995) manikin, with leg
length specified in S10.4.2.1 of Sec. 571.208 of this Part. If the

[[Page 67247]]

specified position of the H-point can be achieved with a range of seat
cushion inclination angles, adjust the seat inclination such that the
most forward part of the seat cushion is at its lowest position with
respect to the most rearward part. All tests specified by this standard
are conducted with the ambient temperature between 18 degrees C. and 28
degrees C.
* * * * *
S5.2.4.2 * * *
(c) Determine if at least 125 mm of the cylinder can completely
pass through the gap. If 125 mm or more of the cylinder can completely
pass through the gap, the gap is not in compliance.
S5.2.6 * * *
(d) Reduce the load at the rate of 250 50 N/minute
until the load is completely removed. Maintain this condition for two
minutes 5 seconds.
* * * * *
S5.2.7 * * *
(a) Backset retention and displacement. For head restraints that
move with respect to the seat when occupant loading is applied to the
seat back, S5.2.7(a)(1) through (8) may be performed with the head
restraint fixed in a position corresponding to the position when the
seat is unoccupied. This fixation is applied to the member(s) that
first transmit(s) the seat back loading from the occupant to the head
restraint.
* * * * *
(5) Maintain the position of the back pan as established in
S5.2.7(a)(4) of this section. Using a 165 2 mm diameter
spherical head form with a surface roughness of less than 1.6 [mu]m,
root mean square, establish the head form initial reference position by
aligning the centerline of the head form perpendicular to the displaced
torso reference line, on the seat centerline, and at a height 65 3 mm below the top of the head restraint. Apply a posterior
initial load that will produce a 37 0.7 Nm moment about
the H-point. After maintaining this moment for 5.5 0.5
seconds, measure the posterior displacement of the head form during the
application of the load.
* * * * *
(7) Reduce the load at the rate of 187 37 Nm/minute
until it is completely removed. Maintain this condition for two minutes
5 seconds.
* * * * *
S5.3 Procedures for dynamic performance. Demonstrate compliance
with S4.3 of this section in accordance with S5.3.1 though S5.3.9 of
this section with a 50th percentile male Hybrid III test dummy
specified in 49 CFR part 572 subpart E, fitted with sensors to measure
head to torso rotation. The dummy with all sensors is to continue to
meet all specifications in 49 CFR part 572 subpart E. The restraint is
positioned midway between the lowest and the highest position of
adjustment, and at any position of backset.
* * * * *
S5.3.4 Seat Adjustment. The following seat adjustments specify
conditions to be met concurrently and are not a sequential list of
adjustments. At each outboard designated seating position, using any
control that primarily moves the entire seat vertically, place the seat
in the lowest position. Using any control that primarily moves the
entire seat in the fore and aft directions, place the seat midway
between the forwardmost and rearmost position. If an adjustment
position does not exist midway between the forwardmost and rearmost
positions, the closest adjustment position to the rear of the midpoint
is used. Adjust the seat cushion and seat back as required by S5 of
this section. If the seat back is adjustable, it is set at an
inclination position closest to 25 degrees from the vertical, as
measured by SAE J826 (July 1995) manikin. If there is more than one
inclination position closest to 25 degrees from the vertical, set the
seat back inclination to the position closest to and rearward of 25
degrees. If the head restraint is adjustable, adjust the top of the
head restraint to a position midway between the lowest position of
adjustment and the highest position of adjustment. If an adjustment
position midway between the lowest and the highest position does not
exist, adjust the head restraint to a position below and nearest to
midway between the lowest position of adjustment and the highest
position of adjustment.
* * * * *

Issued: October 28, 2010.
David L. Strickland,
Administrator.
[FR Doc. 2010-27669 Filed 11-1-10; 8:45 am]
BILLING CODE 4910-59-P