[Federal Register Volume 63, Number 77 (Wednesday, April 22, 1998)]
[Rules and Regulations]
[Pages 19839-19842]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 98-10674]


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DEPARTMENT OF TRANSPORTATION

National Highway Traffic Safety Administration

49 CFR Parts 571 and 589

[Docket No. NHTSA-98-3421]
RIN 2127-AB85


Federal Motor Vehicle Safety Standards; Head Impact Protection

AGENCY: National Highway Traffic Safety Administration (NHTSA), 
Department of Transportation.

ACTION: Denial of petitions for reconsideration.

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SUMMARY: This document denies petitions for reconsideration submitted 
by the American Automobile Manufacturers Association (AAMA) and ASC, 
Incorporated (ASC). On April 8, 1997, NHTSA published a final rule 
amending provisions in Standard No. 201, Head Impact Protection, 
relating to upper interior head impact protection. The amendments 
revised and clarified test procedures, added an optional compliance 
phase-in plan, allowed carry-forward credits to facilitate compliance, 
and excluded small buses from the Standard's upper interior impact 
protection requirements. ASC's petition stated the company's concerns 
about the impact of the final rule on the integrated convertible roof 
and frame designs and requested a further amendment to the definition 
of ``convertible roof frame system.'' AAMA's petition requested that 
NHTSA reconsider and modify the final rule in reference to approach 
angles, moveable side glazing, multiple impacts, the procedure for 
locating CG-F (a reference point corresponding to the location of a 
front seat occupant's head), and the definition of ``forehead impact 
zone.''

DATES: Petition Date: Any petitions for reconsideration of this denial 
must be received by NHTSA no later than June 8, 1998.

ADDRESSES: Any petitions for reconsideration should refer to the docket 
and notice number of this notice and be submitted to: Administrator, 
National Highway Traffic Safety Administration, 400 Seventh Street, SW, 
Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: For legal issues: Mr. Otto Matheke, 
Office of the Chief Counsel, NHTSA, 400 Seventh Street, SW, Washington, 
DC 20590. Mr. Matheke's telephone number is (202) 366-5253. His 
facsimile number is (202) 366-3820. For non-legal issues: Dr. William 
Fan, Office of Crashworthiness Standards, NPS-11, Dr. Fan's telephone

[[Page 19840]]

number is (202) 366-4922. His facsimile number is (202) 366-4329.

SUPPLEMENTARY INFORMATION: On August 18, 1995, the National Highway 
Traffic Safety Administration (NHTSA) published a final rule (60 FR 
43031--Docket No. 92-28; Notice 4) amending Federal Motor Vehicle 
Safety Standard (FMVSS) No. 201, ``Occupant Protection in Interior 
Impact,'' to require passenger cars, trucks, buses, and multipurpose 
passenger vehicles (MPVs) with a gross vehicle weight rating (GVWR) of 
4,536 kilograms (10,000 pounds) or less to provide head protection 
during a vehicle crash when the occupant's head strikes pillars, side 
rails, headers, or the roof of the vehicle. The final rule specifies a 
24 km/h (15 mph) in-vehicle component impact test that uses a free-
motion headform (FMH). The injury criterion is the HIC limit of 1,000. 
The effective date is a four-year phase-in plan (10 percent, 24 
percent, 40 percent, 70 percent and 100 percent) beginning on September 
1, 1998. An optional implementation plan is a one-year phase-in plan (0 
percent and 100 percent) beginning on September 1, 1998. A final stage 
manufacturer or alterer must comply with the standard's upper interior 
impact requirements for vehicles manufactured on or after September 1, 
2002.
    The agency received ten petitions for reconsideration in response 
to the August 1995 final rule. In response to those petitions, NHTSA 
published another final rule on April 8, 1997 (62 FR 16718--Docket No. 
92-28; Notice 7) revising test procedures, adding an optional phase-in 
plan, allowing carry-forward credits, and excluding small buses from 
the upper interior head impact requirements. In addition, NHTSA 
initiated a new rulemaking concerning alternative procedures for 
testing dynamically deployed head protection systems.
    In response to the April 1997 final rule, the American Automobile 
Manufacturers Association (AAMA) and ASC, Incorporated submitted new 
petitions for reconsideration. The ASC petition requested exclusion of 
the convertible top from the FMH impact requirements, while the AAMA 
petition addressed technical issues in general areas.

The ASC Petition for Reconsideration

    On May 22, 1997, ASC submitted a petition for reconsideration 
arguing that the amendments to the August 1995 final rule did not 
address current convertible top designs that include integrated roof 
and frame systems (e.g., a removable hardtop). ASC also indicated its 
belief that the addition of padding to an integrated convertible roof 
and frame system would prevent the roof from folding into the available 
storage area below the beltline or in the rear storage area, thereby 
interfering with rear vision or requiring elimination of the rear seat 
in some models. Compliance with Standard No. 201's upper interior 
impact requirements would, in ASC's view, limit future design and 
development of convertible tops to traditional vinyl or canvas top 
convertibles with separate frames. As a result, production and sale of 
more ``advanced'' integrated convertible top designs would become 
impracticable. Accordingly, in its petition for reconsideration, ASC 
requested that the convertible roof frame definition in the amended 
final rule be revised to read as follows:

    Convertible roof frame means the frame of a convertible roof and 
the roof and frame of a convertible with an integrated roof and 
frame system which is capable of folding and being stored below the 
beltline or in the rear storage compartment of the vehicle.

Without this revision, ASC believes that the automobile industry will 
not be able to continue production and development of new convertible 
automobile designs with integrated roof and frame systems.
    The agency notes that the exclusion of convertible roofs and 
linkages is an issue that was examined extensively throughout the 
rulemaking process leading up to the August 1995 and April 1997 final 
rules. In the August 1995 final rule, NHTSA agreed to exclude 
``convertible roof frames and linkage mechanisms because the presence 
of a countermeasure such as padding would interfere with their 
movement'' (60 FR 43031, at 43047). The April 1997 final rule, issued 
in response to petitions for reconsideration filed after the issuance 
of the August 1995 final rule, deleted the word ``metal'' from the 
definition of ``convertible roof frame'' in response to objections that 
limiting excluded frames to those made of metal was design restrictive 
(62 FR 16718, 16721).
    ASC's request for reconsideration raises an issue that NHTSA 
examined prior to the issuance of the August 1995 final rule and the 
April 1997 final rule. In the preamble to the April 1997 final rule, 
the agency observed that commenters did not provide any support for the 
claim that countermeasures could not be installed on areas other than 
convertible roof frames and linkage mechanisms. NHTSA further stated 
that rigid convertible tops could produce head injuries and that the 
agency believed that protection should be provided for all the hard 
areas inside a vehicle unless it is not practicable to do so. The ASC 
petition does not include any new data or information demonstrating 
either that the agency's prior decision not to exclude convertible 
roofs was wrong or that newer roof designs require reconsideration of 
the issue.
    In the absence of new data, the agency considered the ASC petition 
based on the agency's current knowledge of vehicle roof designs. The 
upper roof area of a typical passenger car is relatively soft in 
comparison with the pillar and side rail components of the vehicle. 
Based on the agency's current knowledge, the upper roof structure of a 
typical production car does not require any padding to comply with the 
FMH impact requirements. The roof structure is basically a shallow, 
thin shell design with some rib-type reinforcement members (roof cross-
member and/or roof bow member). A properly designed thin shell 
structure is a very effective energy absorptive design. A roof 
structure made of sheet metal or other flexible materials should be 
able to meet Standard 201's requirements without the extensive use of 
padding or other countermeasures. ASC has not submitted any data 
indicating that convertible hardtops cannot be made as flexible as a 
conventional roof structure. NHTSA believes that there is not a 
sufficient basis for treating convertible hardtops differently from 
regular vehicle roof structures and that convertible hardtops should be 
subject to Standard No. 201's upper interior impact requirements.
    Agency test data indicate that the upper roof of many production 
cars can comply with those requirements without any modification. An 
integrated convertible roof, except frames and linkage mechanisms, is 
basically a shallow thin shell design that is soft and smooth. Since 
convertible roof frames and linkage mechanisms are excluded from the 
final rule, the design of the remainder of the convertible hardtop roof 
should not present additional compliance difficulties. The agency 
believes that integrated convertible roof designs should be able to 
meet Standard 201 when the roof top membrane structure is tested using 
the FMH impactor at a speed up to 24 km/h (15 mph). Since ASC has not 
demonstrated that a ``hard'' convertible top that meets Standard 201's 
upper interior impact requirements cannot be built or is otherwise 
impracticable, the agency is denying ASC's petition.

[[Page 19841]]

The AAMA Petition for Reconsideration

    On May 23, 1997, AAMA submitted a petition for reconsideration 
requesting that NHTSA consider additional changes to Standard No. 201 
to address concerns relating to approach angles in compliance testing, 
hinged and moveable glazing, multiple FMH impacts, the procedure for 
locating a reference point that corresponds to the head position of a 
front seat occupant and is known as CG-F, and the definition of the 
forehead impact zone of the FMH.
    In defining the trajectory of the FMH when it is propelled at 
target points located on all pillars except the A-pillar, the April 
1997 final rule specified a vertical approach angle range for the FMH 
of +50 to -10 degrees. AAMA believes that the minimum vertical angle of 
-10 degrees may not be sufficient to allow the FMH to make proper 
contact with certain targets. In AAMA's view, simultaneous contact of 
the forehead and chin may occur when the pillar surface on which the 
target is located is canted (from top to bottom) toward the inside of 
the vehicle at an angle of approximately 10 degrees. AAMA recommended 
that the existing target exclusion in S6.1 be expanded so that targets 
that cannot be tested using the approach angle limits specified in 
S8.13.4 would be excluded from the upper interior impact requirements.
    NHTSA does not believe that the exclusion in S6.1 must be modified 
to address AAMA's concern. As it appears in the April 1997 final rule, 
S6.1 indicates that the FMH impact requirements do not apply to any 
target that cannot be located using the procedure of S10. S10(b) 
specifies that, except as specified in S10(c), if there is no 
combination of horizontal and/or vertical approach angles specified in 
S8.13.4 at which the forehead impact zone of the FMH can contact one of 
the targets located using the procedures in S10.1 through S10.13, the 
center of that target is moved to any location within a 25 mm sphere, 
centered on the center of the original target and measured along the 
vehicle interior, that the forehead impact zone can contact at one or 
more combination of angles. S10(c) specifies that if there is no point 
within the sphere specified in S10(b) which the forehead of the FMH can 
contact at one or more combination of horizontal and/or vertical 
approach angles specified in S8.13.4, the sphere is increased by
25 mm increments until it contains at least one point that can be 
contacted at one or more combination of angles. In addition, S8.13.4.2 
specifies procedures for determining vertical approach angles that 
would avoid simultaneous contact of the forehead and chin. If a 
specific target cannot be tested using the approach angle limits 
specified in S8.13.4, the target should be relocated using S10(b) or 
S10(c). Accordingly, NHTSA concludes that an amendment to the final 
rule is not necessary to resolve AAMA's concern.
    As noted above, the April 1997 final rule excluded convertible roof 
frames and linkage mechanisms from Standard No. 201's upper interior 
impact requirements. AAMA's petition for reconsideration requested that 
the hinge and latch components for sunroofs and moveable side glazing 
be accorded similar treatment. The organization argued that these 
components, like convertible roof frames and linkage mechanisms, cannot 
function if they must be padded to meet Standard No. 201.
    NHTSA does not believe that the same considerations that apply to 
convertible roof frames and linkage mechanisms also apply to sunroof 
and side window latches and hinges. First, convertible roofs are large 
and complex compared to sunroofs and moveable glazing, and therefore 
require much stronger latches and anchorages to stabilize the whole 
roof during high speed travel. Second, the size and complexity of 
convertible roof mechanisms are such that padding those components may 
interfere with the operation of the convertible roof top. In contrast, 
the latches and hinges used in the sunroofs and moveable glazing of 
current production vehicles are usually small in size and made of, or 
enclosed with, plastic materials. Although the amended final rule does 
not identify the latches or hinges of moveable side glazing or sunroofs 
as targets for compliance testing, these components could be located in 
target areas. However, the agency believes that padding these 
fasteners, if required, would not significantly affect the operation of 
sunroofs and side windows. NHTSA also notes that similar components, 
such as safety belt anchorages and grab handles, may also have to be 
padded. The agency is not aware of any justification for 
differentiating between the latter and sunroof or side window hinges 
and latches.
    The April 1997 final rule specified that a FMH impact may not occur 
within 150 mm distance of any prior FMH impact. AAMA believes that the 
minimum distance of 150 mm is not adequate to address complex impact 
conditions. The organization contends that the type of countermeasure, 
the target location, the size of target component, the impact approach 
angles, and the interaction of chin loading are factors that may lead 
to multiple impacts affecting test results. Since damage to trim as a 
result of an impact cannot be readily detected through visual 
observation and manufacturers cannot reliably anticipate the effects on 
material or component performance, AAMA contends that only one impact 
be allowed for each component.
    The agency does not agree. In order to complete vehicle compliance 
tests with one vehicle, NHTSA concluded in the final rule that multiple 
FMH impacts on a component should be allowed, that impacts on both left 
and right side components should be allowed, but that an overlap of two 
FMH impacts should not be allowed. The agency determined that the 
minimum distance between two targets should be 150 mm (6 inches). In 
order to allow padding to recover from a FMH impact, a 30-minute 
waiting period is specified if the next impact is to be on the same 
component.
    NHTSA believes that the existing minimum distance between impact 
points is adequate. The maximum width of the Hybrid III headform is 150 
mm and the effective width of the forehead impact zone is much less 
than 150 mm. With two adjacent targets at 150 mm distance, overlapping 
of the FMH contact should not occur. The agency also believes that 
manufacturers may test in a fashion that minimizes multiple impacts. 
The amended final rule allows testing of both left and right side 
components; multiple impacts would generally occur during the A or B-
pillar component tests. If target selection is made using both side 
components, the actual distance between two adjacent targets could be 
much larger than the specified minimum distance of 150 mm. In addition, 
NHTSA testing indicates that the foam damage area from an impact is 
smaller than the forehead impact zone.
    AAMA also argued that only one FMH impact should be allowed for 
each component due to the uncertainty involved in choosing a design 
and/or material for compliance testing. NHTSA notes that AAMA has 
raised this issue in a previous petition for reconsideration. In that 
instance, AAMA did not submit any test data establishing that 
permitting only a single test for each component is necessary or 
desirable. In its current request, AAMA has not submitted any new test 
data supporting such a contention. NHTSA has previously declined to 
adopt a limitation on the number of impacts per component and declines 
to do so now.

[[Page 19842]]

    The agency also wishes to make it clear that where Standard 201, or 
other Federal motor vehicle safety standards, do not address a specific 
test condition, vehicles must comply in all circumstances consistent 
with anticipated use of the vehicle by occupants. Multiple impacts to 
one component are an example of a circumstance that might be 
encountered in a crash. NHTSA may therefore test single components with 
multiple impacts when performing compliance testing under Standard 201.
    The AAMA petition also requests that the agency rectify an apparent 
conflict involving the procedure for locating CG-F by use of the 
``seating reference point (SgRP).'' The SgRP is a single point which 
establishes the rearmost normal design driving or riding position. In 
Standard No. 201, S8.12(a)(1) uses SgRP with the seat in its rearmost 
normal design or driving position to locate the rearmost CG-F (CG-F2). 
The forwardmost CG-F (CG-F1) is, according to S8.12(a)(2), located 
horizontally forward of CG-F2 by the distance equal to the fore and aft 
distance of the seat track. Because S8.12(a)(2) describes CG-F1 as the 
head center of gravity with the seat in its forwardmost adjustment 
position, AAMA believes that S8.12 implies that the reference point to 
be used is not SgRP, which is a single point, but rather the design H-
point, which can occupy a number of points according to the seat 
adjustment. In its petition, AAMA suggested that a conflict existed and 
requested that it be resolved.
    When the August 1995 final rule was published, NHTSA was requested 
to change the reference point from the SgRP to the H-point. The agency 
explained in the preamble of the April 1997 final rule that a change of 
the reference point is not necessary. This is because the only point 
used for locating CG-F1 and CG-F2 is the single SgRP. The agency notes 
that, prior to a recent correcting amendment published on January 2, 
1998 (63 FR 27), S8.12(a)(1) incorrectly specified that C--F2 should be 
located with the seat in its rearmost adjustment position rather than 
the rearmost normal design driving or riding position. As the SgRP only 
exists in the latter position and not the former, AAMA and others could 
have reasonably concluded that NHTSA intended that the design H-point 
rather than the SgRP be used to locate CG-F1 and CG-F2. The reference 
in S8.12(a)(2) to the seat being in its forwardmost adjustment position 
to assist in describing CG-F1 may have created further opportunities 
for misunderstanding. However, the agency believes that the correcting 
amendment to S8.12(a)(1) resolved this issue and that further 
rulemaking is not required.
    AAMA also suggested that the existing definition of the forehead 
impact zone is in error. In its petition, AAMA recommended that in 
S8.10(d), the word ``vertical'' be replaced with ``horizontal'' as it 
refers to a plane along the contour of the outer skin of the forehead 
of the FMH. S8.10(d) specifies the procedure for locating the upper 
boundary of the forehead impact zone by directing that a line be drawn 
along the contour of the headform and through a point on a vertical 
line in the midsagittal plane of the FMH so that the line is bisected 
by that point. This line is described as being coincident to a vertical 
plane, while the procedure for locating the lower horizontal boundary, 
found in S8.10(c), specifies that the lower boundary line be coincident 
to a horizontal plane. AAMA's belief that the use of the vertical plane 
in S8.10(d) is in error may be premised on the use of the horizontal 
plane in S8.10(c) for locating a similar line. However, at the point 
where the upper boundary of the forehead impact zone is located, the 
contours of the FMH are such that the use of a horizontal plane for 
locating the upper boundary would result in the forehead impact zone 
extending along the sides of the FMH. NHTSA has determined that the use 
of a vertical plane in describing this procedure is more appropriate. 
Use of a horizontal plane to describe the forehead impact zone would 
include part of the side of the head in the forehead impact zone.
    Based on the foregoing, NHTSA denies the AAMA and ASC petitions.

    Authority: 49 U.S.C. 30103, 30162; delegation of authority at 49 
CFR 1.50 and 501.8.

    Issued on: April 10, 1998.
Ricardo Martinez,
Administrator .
[FR Doc. 98-10674 Filed 4-21-98; 8:45 am]
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