[Code of Federal Regulations]
[Title 49, Volume 5, Parts 400 to 999]
[Revised as of October 1, 1997]
From the U.S. Government Printing Office via GPO Access
CHAPTER V--NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
PART 571--FEDERAL MOTOR VEHICLE SAFETY STANDARDS6--Table of Contents
Subpart B--Federal Motor Vehicle Safety Standards
Sec. 571.218 Standard No. 218; Motorcycle helmets.
S1. Scope. This standard establishes minimum performance
requirements for helmets designed for use by motorcyclists and other
motor vehicle users.
S2. Purpose. The purpose of this standard is to reduce deaths and
injuries to motorcyclists and other motor vehicle users resulting from
S3. Application. This standard applies to all helmets designed for
use by motorcyclists and other motor vehicle users.
Basic plane means a plane through the centers of the right and left
external ear openings and the lower edge of the eye sockets (Figure 1)
of a reference headform (Figure 2) or test headform.
Helmet positioning index means the distance in inches, as specified
by the manufacturer, from the lowest point of the brow opening at the
lateral midpoint of the helmet to the basic plane of a reference
headform, when the helmet is firmly and properly positioned on the
Midsagittal plane means a longitudinal plane through the apex of a
reference headform or test headform that is perpendicular to the basic
plane (Figure 3).
Reference headform means a measuring device contoured to the
dimensions of one of the three headforms described in Table 2 and
Figures 5 through 8 with surface markings indicating the locations of
the basic, mid-sagittal, and reference planes, and the centers of the
external ear openings.
Reference plane means a plane above and parallel to the basic plane
on a reference headform or test headform (Figure 2) at the distance
indicated in Table 2.
Retention system means the complete assembly by which the helmet is
retained in position on the head during use.
Test headform means a test device contoured to the dimensions of one
of the three headforms described in Table 2 and Figures 5 through 8 with
surface markings indicating the locations of the basic, mid-sagittal,
and reference planes.
S5. Requirements. Each helmet shall meet the requirements of S5.1,
S5.2, and S5.3 when subjected to any conditioning procedure specified in
S6.4, and tested in accordance with S7.1, S7.2, and S7.3.
S5.1 Impact attenuation. When an impact attenuation test is
conducted in accordance with S7.1, all of the following requirements
shall be met:
(a) Peak accelerations shall not exceed 400g;
(b) Accelerations in excess of 200g shall not exceed a cumulative
duration of 2.0 milliseconds; and
(c) Accelerations in excess of 150g shall not exceed a cumulative
duration of 4.0 milliseconds.
S5.2 Penetration. When a penetration test is conducted in
accordance with S7.2, the striker shall not contact the surface of the
S5.3 Retention system.
S5.3.1 When tested in accordance with S7.3:
(a) The retention system or its components shall attain the loads
specified without separation; and
(b) The adjustable portion of the retention system test device shall
not move more than 1 inch (2.5 cm) measured between preliminary and test
S5.3.2 Where the retention system consists of components which can
be independently fastened without securing the complete assembly, each
such component shall independently meet the requirements of S5.3.1.
S5.4 Configuration. Each helmet shall have a protective surface of
continuous contour at all points on or above the test line described in
S6.2.3. The helmet shall provide peripheral vision clearance of at least
105 deg. to each side of the mid-sagittal plane, when the helmet is
adjusted as specified in S6.3. The vertex of these angles, shown in
Figure 3, shall be at the point on the anterior surface of the reference
headform at the intersection of the mid-sagittal and basic planes. The
brow opening of the helmet shall be at least 1 inch (2.5 cm) above all
points in the basic plane that are within the angles of peripheral
vision (see Figure 3).
S5.5 Projections. A helmet shall not have any rigid projections
inside its shell. Rigid projections outside any
helmet's shell shall be limited to those required for operation of
essential accessories, and shall not protrude more than 0.20 inch (5
S5.6.1 Each helmet shall be labeled permanently and legibly, in a
manner such that the label(s) can be read easily without removing
padding or any other permanent part, with the following:
(a) Manufacturer's name or identification.
(b) Precise model designation.
(d) Month and year of manufacture. This may be spelled out (for
example, June 1988), or expressed in numerals (for example, 6/88).
(e) The symbol DOT, constituting the manufacturer's certification
that the helmet conforms to the applicable Federal motor vehicle safety
standards. This symbol shall appear on the outer surface, in a color
that contrasts with the background, in letters at least \3/8\ inch (1
cm) high, centered laterally with the horizontal centerline of the
symbol located a minimum of 1\1/8\ inches (2.9 cm) and a maximum of 1\3/
8\ inches (3.5 cm) from the bottom edge of the posterior portion of the
(f) Instructions to the purchaser as follows:
(1) ``Shell and liner constructed of (identify type(s) of
(2) ``Helmet can be seriously damaged by some common substances
without damage being visible to the user. Apply only the following:
(Recommended cleaning agents, paints, adhesives, etc., as appropriate).
(3) ``Make no modifications. Fasten helmet securely. If helmet
experiences a severe blow, return it to the manufacturer for inspection,
or destory it and replace it.''
(4) Any additional relevant safety information should be applied at
the time of purchase by means of an attached tag, brochure, or other
S5.7 Helmet positioning index. Each manufacturer of helmets shall
establish a positioning index for each helmet he manufactures. This
index shall be furnished immediately to any person who requests the
information, with respect to a helmet identified by manufacturer, model
designation, and size.
S6. Preliminary test procedures. Before subjecting a helmet to the
testing sequence specified in S7., prepare it according to the
procedures in S6.1, S6.2, and S6.3.
S6.1 Selection of appropriate headform.
S6.1.1 A helmet with a manufacturer's designated discrete size or
size range which does not exceed 6\3/4\ (European size: 54) is tested on
the small headform. A helmet with a manufacturer's designated discrete
size or size range which exceeds 6\3/4\, but does not exceed 7\1/2\
(European size: 60) is tested on the medium headform. A helmet with a
manufacturer's designated discrete size or size range which exceeds 7\1/
2\ is tested on the large headform.
S6.1.2 A helmet with a manufacturer's designated size range which
includes sizes falling into two or all three size ranges described in
S6.1.1 is tested on each headform specified for each size range.
S6.2 Reference marking.
S6.2.1 Use a reference headform that is firmly seated with the basic
and reference planes horizontal. Place the complete helmet to be tested
on the appropriate reference headform, as specified in S6.1.1 and
S6.2.2 Apply a 10-pound (4.5 kg) static verticle load through the
helmet's apex. Center the helmet laterally and seat it firmly on the
reference headform according to its helmet positioning index.
S6.2.3 Maintaining the load and position described in S6.2.2, draw a
line (hereinafter referred to as ``test line'') on the outer surface of
the helmet coinciding with portions of the intersection of that service
with the following planes, as shown in Figure 2:
(a) A plane 1 inch (2.5 cm) above and parallel to the reference
plane in the anterior portion of the reference headform;
(b) A vertical transverse plane 2.5 inches (6.4 cm) behind the point
on the anterior surface of the reference headform at the intersection of
the mid-sagittal and reference planes;
(c) The reference plane of the reference headform;
(d) A vertical transverse plane 2.5 inches (6.4. cm) behind the
the external ear opening in a side view; and
(e) A plane 1 inch (2.5 cm) below and parallel to the reference
plane in the posterior portion of the reference headform.
S6.3 Helmet positioning.
S6.3.1 Before each test, fix the helmet on a test headform in the
position that conforms to its helmet positioning index. Secure the
helmet so that it does not shift position before impact or before
application of force during testing.
S6.3.2 In testing as specified in S7.1 and S7.2, place the retention
system in a position such that it does not interfere with free fall,
impact or penetration.
S6.4.1 Immediately before conducting the testing sequence specified
in S7, condition each test helmet in accordance with any one of the
(a) Ambient conditions. Expose to a temperature of
70 deg.F(21 deg.C) and a relative humidity of 50 percent for 12 hours.
(b) Low temperature. Expose to a temperature of 14 deg.F(-10 deg.C)
for 12 hours.
(c) High temperature. Expose to a temperature of 122 deg.F(50 deg.C)
for 12 hours.
(d) Water immersion. Immerse in water at a temperature of
77 deg.F(25 deg.C) for 12 hours.
S6.4.2 If during testing, as specified in S7.1.3 and S7.2.3, a
helmet is returned to the conditioning environment before the time out
of that environment exceeds 4 minutes, the helmet is kept in the
environment for a minimum of 3 minutes before resumption of testing with
that helmet. If the time out of the environment exceeds 4 minutes, the
helmet is returned to the environment for a minimum of 3 minutes for
each minute or portion of a minute that the helmet remained out of the
environment in excess of 4 minutes or for a maximum of 12 hours,
whichever is less, before the resumption of testing with that helmet.
S7. Test conditions.
S7.1 Impact attenuation test.
S7.1.1 Impact attenuation is measured by determining acceleration
imparted to an instrumented test headform on which a complete helmet is
mounted as specified in S6.3, when it is dropped in guided free fall
upon a fixed hemispherical anvil and a fixed flat steel anvil.
S7.1.2 Each helmet is impacted at four sites with two successive
identical impacts at each site. Two of these sites are impacted upon a
flat steel anvil and two upon a hemispherical steel anvil as specified
in S7.1.10 and S7.1.11. The impact sites are at any point on the area
above the test line described in paragraph S6.2.3, and separated by a
distance not less than one-sixth of the maximum circumference of the
helmet in the test area.
S7.1.3 Impact testing at each of the four sites, as specified in
S7.1.2, shall start at two minutes, and be completed by four minutes,
after removal of the helmet from the conditioning environment.
S7.1.4 (a) The guided free fall drop height for the helmet and test
headform combination onto the hemispherical anvil shall be such that the
minimum impact speed is 17.1 feet/second (5.2 m/sec). The minimum drop
height is 54.5 inches (138.4 cm). The drop height is adjusted upward
from the minimum to the extent necessary to compensate for friction
(b) The guided free fall drop height for the helmet and test
headform combination onto the flat anvil shall be such that the minimum
impact speed is 19.7 ft./sec (6.0 m/sec). The minimum drop height is 72
inches (182.9 cm). The drop height is adjusted upward from the minimum
to the extent necessary to compensate for friction losses.
S7.1.5 Test headforms for impact attenuation testing are constructed
of magnesium alloy (K-1A), and exhibit no resonant frequencies below
S7.1.6 The monorail drop test system is used for impact attenuation
S7.1.7 The weight of the drop assembly, as specified in Table 1, is
the combined weight of the test headform and the supporting assembly for
the drop test. The weight of the supporting assembly is not less than
2.0 lbs. and not more than 2.4 lbs. (0.9 to 1.1 kg). The supporting
assembly weight for the monorail system is the drop assembly weight
minus the combined weight of the test headform, the headform's
clamp down ring, and its tie down screws.
S7.1.8 The center of gravity of the test headform is located at the
center of the mounting ball on the supporting assembly and lies within a
cone with its axis vertical and forming a 10 deg. included angle with
the vertex at the point of impact. The center of gravity of the drop
assembly lies within the rectangular volume bounded by x = -0.25 inch
(-0.64 cm), x = 0.85 inch (2.16 cm), y = 0.25 inch (0.64 cm), and y =
-0.25 inch (-0.64 cm) with the origin located at the center of gravity
of the test headform. The rectangular volume has no boundary along the
z-axis. The x-y-z axes are mutually perpendicular and have positive or
negative designations in accordance with the right-hand rule (See Figure
5). The origin of the coordinate axes also is located at the center of
the mounting ball on the supporting assembly (See Figures 6, 7, and 8).
The x-y-z axes of the test headform assembly on a monorail drop test
equipment are oriented as follows: From the origin, the x-axis is
horizontal with its positive direction going toward and passing through
the vertical centerline of the monorail. The positive z-axis is
downward. The y-axis also is horizontal and its direction can be decided
by the z- and x-axes, using the right-hand rule.
S7.1.9 The acceleration transducer is mounted at the center of
gravity of the test headform with the sensitive axis aligned to within
5 deg. of vertical when the test headform assembly is in the impact
position. The acceleration data channel complies with SAE Recommended
Practice J211 JUN 80, Instrumentation for Impact Tests, requirements for
channel class 1,000.
S7.1.10 The flat anvil is constructed of steel with a 5-inch (12.7
cm) minimum diameter impact face, and the hemispherical anvil is
constructed of steel with a 1.9 inch (4.8 cm) radius impact face.
S7.1.11 The rigid mount for both of the anvils consists of a solid
mass of at least 300 pounds (136.1 kg), the outer surface of which
consists of a steel plate with minimum thickness of 1 inch (2.5 cm) and
minimum surface area of 1 ft \2\ (929 cm \2\ ).
S7.1.12 The drop system restricts side movement during the impact
attenuation test so that the sum of the areas bounded by the
acceleration-time response curves for both the x- and y-axes (horizontal
axes) is less than five percent of the area bounded by the acceleration-
time response curve for the vertical axis.
S7.2 Penetration test.
S7.2.1 The penetration test is conducted by dropping the penetration
test striker in guided free fall, with its axis aligned vertically, onto
the outer surface of the complete helmet, when mounted as specified in
S6.3, at any point above the test line, described in S6.2.3, except on a
fastener or other rigid projection.
S7.2.2 Two penetration blows are applied at least 3 inches (7.6 cm)
apart, and at least 3 inches (7.6 cm) from the centers of any impacts
applied during the impact attenuation test.
S7.2.3 The application of the two penetration blows, specified in
S7.2.2, starts at two minutes and is completed by four minutes, after
removal of the helmet from the conditioning environment.
S7.2.4 The height of the guided free fall is 118.1 inches (3 m), as
measured from the striker point to the impact point on the outer surface
of the test helmet.
S7.2.5 The contactable surface of the penetration test headform is
constructed of a metal or metallic alloy having a Brinell hardness
number no greater than 55, which will permit ready detection should
contact by the striker occur. The surface is refinished if necessary
before each penetration test blow to permit detection of contact by the
S7.2.6 The weight of the penetration striker is 6 pounds, 10 ounces
S7.2.7 The point of the striker has an included angle of 60 deg., a
cone height of 1.5 inches (3.8 cm), a tip radius of 0.02 inch (standard
0.5 millimeter radius) and a minimum hardness of 60 Rockwell, C-scale.
S7.2.8 The rigid mount for the penetration test headform is as
described in S7.1.11.
S7.3 Retention system test.
S7.3.1 The retention system test is conducted by applying a static
load to the retention assembly of a complete helmet, which is mounted,
as described in S6.3, on a stationary test headform as shown in Figure
4, and by measuring the movement of the adjustable portion of the
retention system test device under tension.
S7.3.2 The retention system test device consists of both an
adjustable loading mechanism by which a static tensile load is applied
to the helmet retention assembly and a means for holding the test
headform and helmet stationary. The retention assembly is fastened
around two freely moving rollers, both of which have a 0.5 inch (1.3 cm)
diameter and a 3-inch (7.6 cm) center-to-center separation, and which
are mounted on the adjustable portion of the tensile loading device
(Figure 4). The helmet is fixed on the test headform as necessary to
ensure that it does not move during the application of the test loads to
the retention assembly.
S7.3.3 A 50-pound (22.7 kg) preliminary test load is applied to the
retention assembly, normal to the basic plane of the test headform and
symmetrical with respect to the center of the retention assembly for 30
seconds, and the maximum distance from the extremity of the adjustable
portion of the retention system test device to the apex of the helmet is
S7.3.4 An additional 250-pound (113.4 kg) test load is applied to
the retention assembly, in the same manner and at the same location as
described in S7.3.3, for 120 seconds, and the maximum distance from the
extremity of the adjustable portion of the retention system test device
to the apex of the helmet is measured.
Appendix to Sec. 571.218
Table 1--Weights for Impact Attenuation Test Drop Assembly
Test headform size Weight \1\--1b(kg)
Small................................... 7.8 (3.5 kg).
Medium.................................. 11.0 (5.0 kg).
Large................................... 13.4 (6.1 kg).
\1\ Combined weight of instrumented test headform and supporting
assembly for drop test.
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[38 FR 22391, Aug. 20, 1973, as amended at 39 FR 3554, Jan. 28, 1974; 45
FR 15181, Mar. 10, 1980; 53 FR 11288, Apr. 6, 1988; 53 FR 12529, Apr.