[Federal Register Volume 62, Number 161 (Wednesday, August 20, 1997)]
[Rules and Regulations]
[Pages 44225-44227]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-21910]
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DEPARTMENT OF TRANSPORTATION
National Highway Traffic Safety Administration
49 CFR Part 572
[Docket No. 97-047, Notice 01]
RIN 2127-AG44
Anthropomorphic Test Dummy; Six-Year-Old Child Dummy
AGENCY: National Highway Traffic Safety Administration (NHTSA),
Department of Transportation.
ACTION: Final rule; technical amendment.
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SUMMARY: This document corrects NHTSA's regulation specifying the
characteristics of the test dummy representing a six-year-old child. It
revises the specification for locating the center of gravity (cg) of
the thorax by moving it forward 0.4 inches from the location currently
specified in part 572. This document also amends the dummy's
specifications to show that thorax ballast mass, if used, is mounted on
the inside of the anterior wall of the spine box rather than to its
sides. Both of these changes bring the drawing specifications in line
with the actual construction of the dummy. They are intended to ensure
that there is no confusion among dummy manufacturers and users as to
whether a particular dummy meets the specifications of NHTSA's
regulation.
DATES: The changes made in this rule are effective August 20, 1997. The
incorporation by reference of certain publications listed in this rule
is approved by the Director of the Federal Register as of August 20,
1997.
FOR FURTHER INFORMATION CONTACT: For nonlegal issues: Stan Backaitis,
Office of Crashworthiness Standards (telephone: 202-366-4912). For
legal issues: Deirdre Fujita, Office of the Chief Counsel (202-366-
2992). Both can be reached at the National Highway Traffic Safety
Administration, 400 Seventh St., S.W., Washington, D.C. 20590.
SUPPLEMENTARY INFORMATION: On November 14, 1991, NHTSA published a rule
that added specifications for a 6-year-old child test dummy to NHTSA's
set of regulations for ``Anthropomorphic Test Dummies'' (49 CFR part
572). The dummy was adopted to test child restraint systems for older
children. The specifications for the dummy are set forth in subpart I
of 49 CFR part 572.
The dummy is instrumented with accelerometers for measuring
accelerations in the thorax during dynamic testing. NHTSA was very
specific in describing, in drawings referenced in part 572, subpart I,
the location of the center of gravity (cg) of the dummy's thorax.
However, location descriptions for the cg in the specifications do not
reflect where the cg is actually located in the dummy.
This discrepancy was brought to the agency's attention by First
Technology Safety Systems, Inc. (FTSS), a manufacturer of test dummies.
On January 23, 1996, FTSS petitioned the agency to move the shown
location of the cg of the thorax of the dummy forward 0.4 inches from
the current location specified in drawings that are incorporated into
part 572. Currently, these drawings specify that the cg is 0.9
0.5 inches back from the dummy's shoulder yoke center. The
petitioner requested that the cg be located 0.5 .5 inches
back from the shoulder yoke, ``to fit within the design proportions and
put the cg in line with its current production value.''
NHTSA has examined FTSS's concerns and agrees that the
specification for the cg of the dummy's thorax should be amended.
Accordingly, this document corrects the specification for locating the
cg of the thorax by moving the specified location forward 0.4 inches.
The discrepancy in the current specification usually results when
ballast is used in the dummy's thorax to achieve the required thorax
weight.1 NHTSA had found that in some tests of the dummy,
the screws that affix the ballast firmly to the lateral sides of the
thoracic spine box loosen during dynamic testing. This causes the
ballast to vibrate, resulting in extraneous accelerometer responses. To
prevent the ballast retaining screws from loosening, NHTSA moved the
ballast forward from the lateral sides of the thoracic spine box to the
inside anterior wall of the box, where the ballast could not load the
screws with high dynamic forces. FTSS estimates that the repositioned
ballast could result in the accumulation of the various weight
tolerances within the thorax such that it could put the cg location up
to 0.6 inches forward from its current specification. However, FTSS
believes that relocating the cg 0.4 inches forward from the current
position would be a more representative mean location for all of the
dummy population.
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\1\ The amount of ballast in the thorax depends on how weight
tolerances of the various parts that make up the thorax assembly
accumulate.
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NHTSA has decided to revise Subpart I as requested by FTSS to avoid
potential sources of complaint and confusion caused by a discrepancy in
the cg location of the dummy's thorax. Dummy manufacturers have asked
NHTSA on different occasions to correct inconsistencies between the
part 572 specifications and the actual design and manufacture of the
test dummies, to avoid potential customer complaints that a particular
dummy does not meet the specifications of NHTSA's regulation, even when
the problems are relatively minor and are related to the specification
rather than the dummy. Such conforming amendments to part 572 have been
made several times, e.g., corrections of NHTSA's regulations for the
side impact test dummy, 59 FR 52089; October 14, 1994; and six-year-old
dummy, 60 FR 2896, January 12, 1995.) These amendments are primarily
corrective in nature, and do not affect the impact response of the
dummy in any significant manner.
Today's correction does not impose any additional responsibilities
on any manufacturer and has virtually no effect on the performance of
the dummy. To determine the importance and the effects of thorax cg
location on the dummy's kinematics, a modeling study was performed for
NHTSA by the National Crash Analysis Center of the George Washington
University. The study used an Articulated Total Body computer model to
represent the six-year-old child dummy restrained by a three-point belt
system and seated on a belt-positioning booster seat. The location of
the thorax cg varied over a range of one inch up, down, forward and
backward. The study showed that a movement of the cg one inch forward
did not change the chest g response, reduced head g response by 1 g and
[[Page 44226]]
increased head excursion by 0.5 inches. Assuming a linear relationship
between changes in the cg location and the dummy's responses, moving
the cg of the thorax 0.4 inch forward would amount to no change in
chest g, about 0.4g decrease in the head and 0.2 inch increase in head
displacement. These changes translate to 0 percent change in the torso
response, approximately 0.8 percent decrease in the head injury
criterion and only slightly over 3 percent increase in head
displacement.
It should be noted that these estimates represent theoretical
potential response changes. Actually, there would be no change in the
performance of existing dummies, because existing dummies would not be
changed. This revision brings in line the part 572 specification to the
dummy as actually produced.
This document also corrects Drawing No. SA 106C 001 to show that
the thorax ballast, if used, would be mounted inside the thoracic spine
box, rather than outside as is currently shown. As explained above, in
actual practice, the ballast (if needed) is mounted inside rather than
outside of the spine box on all currently manufactured six-year-old
child dummies. Accordingly, this change would bring in line the subject
drawing to current dummy construction practice.
The following table identifies the drawings that are revised by
this document, and shows the new revision letters for the drawings:
Affected Drawings
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Drawing name Drawing No. Previous revision letter New revision letter
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Crash Test Dummy Assembly; 6-Year- SA 106C 001 (sheet 1). D.......................... E
Old Child.
Crash Test Dummy Assembly; 6-Year- SA 106C 001 (sheet 3). ........................... A
Old Child.
Crash Test Dummy Assembly; 6-Year- SA 106C 001 (sheet 10) B.......................... C
Old Child.
Crash Test Dummy Assembly; 6-Year- SA 106C 001 (sheet 11) C.......................... D
Old Child.
Sternum Thoracic Weld Assembly..... 6C 1000-1............. B.......................... C
Ballast............................ 6C 1021............... A.......................... B
Cover-Chest Accelerometer.......... 6C 909................ ........................... A
Screw Button Head Socket........... 6C 1610-1............. ........................... A
Bushing............................ 6C 1023............... Deleted....................
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This document also updates the reference in Sec. 572.70 to the
address and telephone number of Reprographic Technologies, concerning
where the drawings for the dummy may be obtained.
This document does not impose any additional responsibilities on
any vehicle or dummy manufacturer. Since this rule does not impose any
additional burdens, and because it corrects minor inconsistencies in
the regulation and removes potential sources of question for dummy
manufacturers, NHTSA finds for good cause that notice and an
opportunity for comment on this document are unnecessary, and that this
rule should be effective upon publication.
These minor technical amendments were not reviewed under E.O.
12866. NHTSA has considered costs and other factors associated with
these amendments, and determined that these amendments do not change
any of the conclusions in the November 1991 final rule regarding the
impacts of that final rule, including the impacts on small businesses,
manufacturers and other entities.
List of Subjects in 49 CFR Part 572
Motor vehicle safety, Incorporation by reference.
In consideration of the foregoing, NHTSA amends 49 CFR part 572 as
follows:
PART 572--[AMENDED]
1. The authority citation for part 572 continues to read as
follows:
Authority: 49 U.S.C. 322, 30111, 30115, 30117 and 30166;
delegation of authority at 49 CFR 1.50.
Subpart I--6-Year-Old Child
2. In Sec. 572.70, paragraph (b)(1) is revised to read as follows:
Sec. 572.70 Incorporation by reference.
* * * * *
(b) * * *
(1) Drawing number SA 106 C001 sheets 1 through 18, and the
drawings listed in the parts lists described on sheets 8 through 17,
are available from Reprographic Technologies, 9000 Virginia Manor Rd.,
Beltsville, MD 20705, Telephone (301) 210-5600, Fax (301) 210-5607.
* * * * *
3. In Sec. 572.71, paragraphs (a)(1), (b) and table A are revised
to read as follows:
Sec. 572.71 General description.
(a) * * *
(1) Technical drawings, specifications, and the parts list package
shown in SA 106C 001, sheets 1 through 18, rereleased July 11, 1997;
* * * * *
(b) The dummy is made up of the component assemblies set out in
Table A:
[[Page 44227]]
Table A
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Assembly drawing No. Drawing title Listed on drawing No. Revision
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SA 106C 010........................ Head Assembly......... SA 106C 001, sheet 8.. A
SA 106C 020........................ Neck Assembly......... SA 106C 001, sheet 9.. A
SA 106C 030........................ Thorax Assembly....... SA 106C 001, sheet 10. C
SA 106C 030........................ Thorax Assembly....... SA 106C 001, sheet 11. D
SA 106C 041........................ Arm Assembly (right).. SA 106C 001, sheet 14. A
SA 106C 042........................ Arm Assembly (left)... SA 106C 001, sheet 15. A
SA 106C 050........................ Lumbar Spine Assembly. SA 106C 001, sheet 12. A
SA 106C 060........................ Pelvis Assembly....... SA 106C 001, sheet 13. A
SA 106C 071........................ Leg Assembly (right).. SA 106C 001, sheet 16. A
SA 106C 072........................ Leg Assembly (left)... SA 106C 001, sheet 17. A
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* * * * *
4. In Sec. 572.74, paragraph (a) is revised to read as follows:
Sec. 572.74 Thorax assembly and test procedure.
(a) Thorax assembly. The thorax consists of the part of the torso
assembly designated as SA 106C 030 on drawing SA 106C 001, sheet 2,
Revision A, and conforms to each applicable drawing on SA 106C 001
sheet 10, Revision C (including Drawing number 6C-1610-1 thru -4,
Revision A, titled ``Screw Button Head Socket'', dated September 30,
1996, and Drawing number 6C-1021, Revision B, titled ``Ballast, 6 Yr.
Thoraxc (for 7267A)'', dated September 24, 1996), and sheet 11,
Revision D (including Drawing number SA 6C-909, Revision A, titled
``Cover-chest Accelerometer'', dated September 21, 1996, and Drawing
number 6C-1000-1, Revision C, titled ``Sternum Thoracic Weld Ass'y.'',
dated September 24, 1996).
* * * * *
5. In Sec. 572.74, paragraph (d) is revised to read as follows:
Sec. 572.78 Performance test conditions.
* * * * *
(d) The dummy's dimensions are specified in drawings SA 106C 001,
sheet 3, Revision A, July 11, 1997, and sheets 4 through 6.
* * * * *
Issued: August 12, 1997.
L. Robert Shelton,
Associate Administrator for Safety Performance Standards.
[FR Doc. 97-21910 Filed 8-19-97; 8:45 am]
BILLING CODE 4910-59-P
