Federal Motor Vehicle Safety Standards; Head Restraints, 67233-67247 [2010-27669]

Agencies

• National Highway Traffic Safety Administration
• DEPARTMENT OF TRANSPORTATION

[Federal Register Volume 75, Number 211 (Tuesday, November 2, 2010)]
[Rules and Regulations]
[Pages 67233-67247]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2010-27669]


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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
                                                          (%)      (%)
------------------------------------------------------------------------
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 r