Final 10/17/2007 2010
STANDARD FOR PROTECTIVE HEADGEAR
For Use with Motorcycles and Other Motorized
Vehicles
Special Note to Helmet Users
There are four reasons for you to be interested
in this Standard:
1.
The use of
motorcycles and other motorized vehicles imposes risks of death or permanent
impairment due to head injury.
2.
The proper use
of protective helmets can minimize the risk of death or permanent
impairment.
3.
The protective
capacity of a helmet is difficult to estimate, particularly at the time of
purchase or use. Protective capability
is currently measured by destructive testing which is beyond the means of most
helmet wearers.
4.
Snell
certification backed by ongoing destructive testing samples taken randomly from
dealers and distributors identifies those helmet models providing and
maintaining the highest levels of head protection.
Four of the most critical elements affecting a
helmet's protective properties are:
1.
Impact
management - how well the helmet protects against collisions with large
objects.
2.
Helmet positional
stability - whether the helmet will be in place, on the head, when it's needed.
3.
Retention system
strength - whether the chin straps are sufficiently strong to hold the helmet
throughout a head impact.
4.
Extent of
Protection - the area of the head protected by the helmet.
This
Standard describes simple tests for all four of these items. However, the tests for the second item,
helmet stability, of necessity presume that the helmet is well matched to the
wearer's head and that it has been carefully adjusted to obtain the best fit
possible. Unless you take similar care
in the selection and fitting of your own helmet, you may not obtain the level
of protection that current headgear can provide.
The
Foundation recommends the simple, straightforward procedure recommended to
consumers by most helmet manufacturers:
Position
the helmet on your head so that it sits low on your forehead; if you can't see
the edge of the brim at the extreme upper range of your vision, the helmet is
probably out of place. Adjust the
retention system so that when in use, it will hold the helmet firmly in
place. This positioning and adjusting
should be repeated to obtain the very best result possible. The procedure initially may be time
consuming. Take the time.
Try
to remove the helmet without undoing the retention system closures. If the helmet comes off or shifts over your
eyes, readjust and try again. If no
adjustment seems to work, this helmet is not for you; try another.
This
procedure is also the basis of the test for helmet stability described in this
Standard. This test performs the same
steps but uses standard head forms.
However, you must still perform this procedure for yourself when buying
a helmet and every time you wear a helmet.
Only in this way will you be able to make all the proper adjustments to
get the best fit possible. Furthermore,
your test on your own head will be an improvement on ours; you will determine
whether the helmet is appropriate for you personally.
There
are several other important aspects of helmets to consider. Full face helmets provide a measure of
protection from facial injuries. The
external shell of these helmets includes a rigid "chin" guard that
passes from left to right over the lower part of the face. The Foundation has devised special tests for
the chin bars of full face helmets.
Some
helmets come with a separate structure which bolts to the helmet and which is
intended to cover the lower part of the face.
These removable chin bars are often intended to deflect small stones and
debris encountered in some motorcycle sports and may not be effective facial
protection in falls and accidents. The
Foundation does not test removable chin bars and considers any headgear
equipped with them to be an open face helmet.
Helmets
may also be equipped with a chin or full face guard that pivots or flips up for
the rider’s convenience. These
structures are considered as integral parts of the helmet and helmets equipped
with them are considered full face helmets and are required to meet all of the
test criteria for full face helmets.
These flip up face guards must always be used in their locked position,
or in accordance with the instructions from the manufacturer. Misuse of these fixtures may diminish the
overall protective capabilities of the helmet.
If
a full face helmet is equipped with a face shield, it may also provide a
measure of eye protection. The
Foundation tests the face shields of full face helmets for particle penetration
resistance. Face shields provided with
open face helmets generally do not provide the same levels of eye protection
and, for that reason are not considered.
The
shells of both open and full face helmets should also provide a measure of
protection from penetration. The
Foundation tests the shells of both full and open face helmets for penetration
resistance.
Effective
headgear must be removable. Paramedics
and other emergency personnel must be able to quickly remove headgear from
accident victims in order to check for vital signs and to perform emergency
procedures. The Foundation has devised
tests and criteria for helmet removability.
The
Foundation tests helmets for visual field.
The helmet must provide a minimum range of vision appropriate to its use
as measured on standard head forms. Most
Snell certified helmets will meet the requirements stated in this Standard and
are considered appropriate for street use.
However, the Foundation may also certify headgear with much more
restricted visual fields for use only in carefully controlled competitive environments. Such headgear will include warning labels
identifying them as appropriate only for certain activities.
Be
absolutely certain that your helmet is appropriate for your intended uses. Furthermore, since the range of vision you
obtain may vary considerably from our measurement, be absolutely certain that
the helmet and face shield permit you adequate vision.
There
are several important factors which the Foundation does not consider directly
but which bear on the effectiveness of protective helmets. Be certain your helmet is wearable, that is,
that it's comfortable and adequately ventilated when worn for prolonged
periods. Few people will wear an
uncomfortable helmet. A helmet that is
not worn won't protect anyone. Also,
while you’re trying the helmet on, take a good look in a mirror and ask some
friends what they think. Most people
will quit using an ugly helmet much more quickly than one that is merely
uncomfortable.
Check
for conspicuity. Bright colors and
reflective patches will make you more visible to others and therefore less
likely to be involved in a collision.
All your riding gear and especially your helmet should be unmistakable,
even to the most inattentive driver.
FOREWORD
In
a motorcycle accident, the rider may suffer injury or death. Helmets on the market today offer varying
degrees of protection, but the consumer has little basis for judging the
relative effectiveness of a given model.
This Standard presents rational methods for identifying those helmet
models which definitely meet specified standards for impact (crash) protection
and retention system strength and, afterwards, identifying those which definitely have ceased to meet
those standards.
The
Snell Foundation urges that protective helmets be required for all individuals
participating in supervised racing events and encourages the general public to
wear helmets which meet appropriate performance standards[1].
This
2010 Standard establishes performance characteristics suitable for motorcycling
and for use with other open motorized vehicles in which the driver and
passengers may not be enclosed such as boats, motorized carts, all-terrain
vehicles and snowmobiles. This
Standard does not establish construction and material specifications. The Foundation does not recommend specific
materials or designs. Manufacturers
voluntarily submit helmets to be tested to this Standard and if the submitted
helmets pass, a certification is issued.
The
Foundation will make available the identity of those products which have been
Snell certified but will not attempt to rank those products according to
performance nor to any other criteria.
Neither does the Foundation distinguish between the needs of
participants in competitive events and those of the general public.
All
of the requirements described herein, including both initial certification and
random sample testing, are an integral part of this Standard. No helmet can satisfy the Standard unless it
is subject to both certification and random sample testing by the Foundation.
Snell
certification for protective headgear requires a specific contractual agreement
between the primary headgear manufacturer and the Foundation. Certification procedures may be obtained upon
application to the Foundation.
SNELL
MEMORIAL FOUNDATION is a registered certification mark and M2010 is a
certification mark of the Snell Memorial Foundation.
INTRODUCTION
This
Standard addresses the problem of protecting the head from direct impact with
surfaces or objects that might be encountered in a motorcycling accident. The Standard prescribes direct measures of
several factors bearing on a helmet's ability to protect the head as well as
its general serviceability as motorcyclist headgear. Thus, this Standard is directed towards the
kinds of performance bearing on head protection that may not readily be
discernable by even knowledgeable consumers at the time of purchase.
Some
of these performance requirements have been expressed in terms of limitations
on the various components and features of the single general helmet
configuration currently available. These
expressions have been used only for the sake of clarity and should not be
misinterpreted as requiring specific configurations or materials. As newer helmet technologies appear, these
limitations will be re-examined and, perhaps, restated.
A
motorcycle helmet consists generally of a rigid head covering and a retention
system composed of flexible straps and hardware. The rigid covering consists of a strong, stiff
outer shell and a crushable liner. The
stiff outer shell protects by its capacity to spread a concentrated load at its
outer surface over a larger area of the liner and the wearer's head. The crushable liner protects the head from
direct impact by its capacity to manage impact energy. Since
there is no certain way to anticipate the severity of a head impact or whether
the impact surface will be such that it will spread the load over the helmet or
concentrate it at a single point, the most generally effective helmet will
combine the strongest, stiffest possible outer shell with a liner chosen to
limit the peak deceleration of the wearer’s head to within tolerable limits.
The
retention system holds the headgear in position throughout normal usage and
especially during falls and accidents, ensuring that the helmet will be in
place to manage a direct impact. This
Standard applies two different tests to the retention system. The first of these tests for stability by
fitting the headgear to a standard head form and then attempting to displace it
by applying tangential shock loadings.
The second tests retention system strength by applying a shock load to
the system components through a simulated chin.
The
quality of the fit and the care taken with the adjustments are absolutely
critical elements in these tests. The
manufacturer must provide suitable guidance so that the wearer will be able to
select and adjust headgear to obtain the necessary quality of fit and
positional stability.
The
capacity for impact protection is determined by direct measurement of the shock
delivered through the helmet to a head form when the helmeted head form is
dropped in a specified manner onto any of three unyielding anvils.
Most
motorcycle helmets are intended to accommodate a range of head sizes and shapes. Various thicknesses of resilient padding are
sometimes placed within otherwise identical helmets during production or during
fitting to configure the helmet to several different ranges of head size. This resilient padding does not significantly
affect the way the helmet absorbs and attenuates impact and is not directly
addressed in this Standard.
The
helmet must also resist penetration by sharp edged and pointed projections and
projectiles. This capacity is tested by
placing the helmet on a head form and dropping a metal cone of specified mass
and geometry onto the shell. The tip of
this cone must not penetrate to the head form.
Similarly,
the helmets must resist chemical attack by bodily fluids as well as solvents
and chemicals associated with motorsports.
This capacity may be tested by applying a solvent mix before further
conditioning and testing.
Full
face helmets provide a measure of facial protection in addition to the impact
protection generally sought. The
principle feature of a full face helmet is a chin bar that extends forward to
cover the jaw area converting the facial opening into a visual port. Frequently, a face shield is also provided so
that the wearer's face is completely covered.
In
order to be considered a full face helmet, the chin bar must be an integral
part of the helmet structure. This
interpretation specifically includes configurations in which the chin bar
pivots about a hinge up and away from the face but excludes simple “bolt-on”
chin coverings. The Standard then tests
the rigidity of the chin bar by dropping a weight onto it at a specified
velocity so as to attempt to force the chin bar toward the interior of the
helmet. The chin bar must not deflect
more than a specified amount.
If
a face shield is provided with a full face helmet, then this face shield must
resist penetration by small particles. A
sharp lead pellet of a specified weight is directed into the face shield at a
specified velocity. The pellet must not
penetrate into the helmet interior.
This
Standard also includes a test intended to determine whether the headgear may be
removed from an unconscious accident victim quickly, easily and reliably in
spite of any damage the headgear might reasonably be expected to sustain. Traditional helmet architectures have
satisfied this requirement so readily that many Standards including previous
Snell Foundation Standards have not mentioned it. Even so, it is unthinkable that a headgear
might protect its wearer in an accident only to thwart attempts at rescue afterward.
Inadequate
ventilation may render a helmet unwearable in hot climates, especially if the
helmet is full faced. But this Standard
makes no direct demands on either the quantity or quality of air flow to the
wearer.
Other
general features of motorcycle helmets may include eyeshades and accommodations
for goggles, and visibility enhancements such as bright colors and reflective
surfaces. These features all deal with
matters of safety and comfort that are not directly addressed in this Standard
but which merit the consideration of wearers as well as manufacturers.
Although helmet use has been shown to reduce
the risk of head injuries significantly, there are limits to a helmet's
protective capability. No helmet can
protect the wearer against all foreseeable accidents. Therefore injury may occur in accidents which
exceed the protective capability of any helmet including even those helmets
meeting the requirements of this Standard.
A
helmet's protective capability may be exhausted protecting the wearer in an
accident. Helmets are constructed so
that the energy of a blow is managed by the helmet, causing its partial
destruction. The damage may not be
readily apparent and the Foundation strongly recommends that a helmet involved
in an accident be returned to the manufacturer for complete inspection. If it is not possible to do so, the helmet
should always be destroyed and replaced.
Finally,
the protective capability may diminish over time. Some helmets are made of materials which
deteriorate with age and therefore have a limited life span. At the present time, the Foundation
recommends that motorcycle helmets be replaced after five (5) years, or less if
the manufacturer so recommends.
CONSTRUCTION
A. General
The
assembled helmet shall have smooth external and internal surfaces. Any feature projecting more than 7 mm beyond
the outer surface must readily break away; all other projections on the outer
surface shall be smoothly faired and offer minimal frictional resistance to
tangential impact forces. Rivets and
similar projections into the helmet interior must offer no laceration or
puncture hazard. Restraint clips may be
used at the rear or on the side of the helmet.
The helmet shall provide as nearly uniform impact protection over the
entire protected area as is possible.
If
the absence of any detachable component of the helmet does not prevent its
being worn, then this absence must not compromise either the retention system
or the impact protection. If any part of
the helmet detaches during testing, it must offer no laceration or puncture
hazard nor reduce the coverage of the head.
If
the manufacturer provides add-ons such as visors, face shields and neck
curtains with the helmet, these add-ons must not lessen the protective
capability of the basic helmet nor reduce the visual field below standard
requirements nor create a direct hazard for the wearer.
B. Shell
If
rivets are used, the heads shall not have sharp edges and shall not project
more than 2 mm from the outer surface of the helmet.
C.
Materials
Ideally,
materials used in the manufacture of the helmet should be of durable quality
and not be harmed by exposure to sun, rain, dust, vibration, sweat or products
applied to the skin or hair. Similarly,
the materials should not degrade due to temperature extremes likely to be
encountered in routine storage or transportation. Materials which are known to cause skin irritation or are
conducive to disease shall not be used for the parts which contact the
skin. Materials which support the growth
of fungi or algae shall not be used.
Fabric lining or padding materials, if used, may be detachable for the
purpose of washing so long as their absence does not degrade the protective
capabilities of the helmet.
D. Finish
All
edges of the helmet shall be smoothed and rounded with no metallic parts or
other rigid projections on the inside of the shell that might injure the
wearer's head in the event of impact.
E.
Retention System
The
retention system shall be designed so as to discourage misuse. That is, of all the ways in which the
retention system might be used, the design use shall be the simplest and
quickest to implement. Helmets shall not
be fitted with "non-essential" features which, if misused, can
degrade the performance. Quick release
buckles, if used, shall not be able to be released inadvertently.
Fabric
chinstraps, if used, shall not be secured to the shell by a bolt, pin or rivet
passing through the fabric itself.
Although other alternatives may be proposed, the preferred method of
attachment is that the strap be looped through and sewn about a metal hanger
which can then be secured to the shell by bolt, rivet or other appropriate
means.
F. Peripheral Vision
The
helmet shall provide peripheral visual clearance as measured using a reference head
form appropriate to the size of the helmet.
This peripheral vision includes a horizontal clearance of at least 210º, an upward clearance of at least 7º and a
downward clearance of at least 30º.
However, this downward clearance makes specific allowance for breath
deflectors. These clearances are
described in terms of planes fixed in the reference head forms.
Some
competitive applications may require helmets with more restricted visual
fields. When justified, special addenda
to this Standard will define reduced visual fields, the procedures for
determining whether a helmet satisfies the requirement and the additional
labeling requirements warning that the headgear may be appropriate only for
certain uses.
G. Sizing
The requirements of this standard are such that most
helmets will perform optimally only when tested within a range of head
circumferences. Outside this range, helmets
may still provide a measure of protection but they may not meet requirements
for certification. The manufacturer must
specify this entire range when helmets are submitted for certification. Later, when helmets are distributed for sale,
every helmet shall include a permanent label indicating the range of head
circumferences for which it is intended.
QUALIFICATIONS
FOR CERTIFICATION
For
qualification testing, helmets shall be in the same condition as those offered
for sale. No helmet or component which
has been subjected to any tests described in this Standard shall be offered for
sale after testing.
At least five (5) and as many as seven (7)
complete helmets must be submitted by the manufacturer for a certification test
program for each distinct structural configuration of the models offered for
sale. All but one of these samples will
be destroyed in testing; the untested sample shall be retained for comparison
and reference. If different fit pad
configurations are planned in order to accommodate this head gear for different
size ranges, five of the samples submitted must be configured for the largest size
range. If seven samples are considered
necessary, the remaining two samples must be configured for the smallest
intended size. Additional samples
representing different fit pad configurations may also be provided at the
discretion of the submitter.
MODIFICATIONS
Cosmetic
changes to certified headgear are permissible.
Such changes are generally limited to marking or trimming the headgear
with manufacturer approved paint or tape.
Otherwise, modifications to certified headgear effectively create new
configurations which shall not have the confidence and certification of the
Foundation until properly evaluated.
Manufacturers must not place the Foundation's certification label in any
modified headgear without the Foundation’s written authorization.
The
Foundation recommends that helmet owners not modify or contract with someone
else to modify their helmets. Any
structural modification may adversely affect a helmet's protective
capability. The Foundation’s
certification and, quite likely, all manufacturer warranties apply to the
headgear only in its as manufactured condition.
RANDOM
SAMPLE TESTING
In
addition to the certification testing, the Foundation will routinely obtain and
test samples of previously certified models.
These samples will be selected from among those stocks intended for
retail sale to consumers. In this
manner, the Foundation will attempt to ensure that the helmets made available
to the public continue to meet the performance requirements of this Standard.
For those cases in which helmets are
provided directly to users and do not pass through a normal sales distribution
system, the Foundation will set up alternative procedures to monitor certified
products. Specifically, if helmets are
provided directly to teams or individuals for use in events, the Foundation
must have access to the helmets for spot checking and non-destructive
evaluation.
LABELING
AND MARKING
Each
helmet shall have durable, visible and legible labeling identifying the
manufacturer, the month and year of manufacture, the model and the size. Labeling shall be uncoded and either in
English or a language common to the area where the helmets are to be
distributed. The headgear shall also be
labeled to the following effect:
1.
No helmet can protect the wearer against all foreseeable impacts. However, for maximum protection, the helmet
must be of good fit and the retention system must be securely fastened to
retain the helmet. The helmet, when
fitted and fastened, shall not be removed easily.
2.
This helmet is so constructed that the energy of an impact may be absorbed
through its partial destruction, though damage may not be visible. If it suffers an impact, it must either be
returned to the manufacturer for inspection or be destroyed and replaced.
3.
Intended for head circumferences from XX cm through YY cm.
If
any of the helmet components are sensitive to common solvents, adhesives,
paints or cleansers; the helmet must also bear labels to the following effect:
This
helmet can be seriously damaged by some common substances without visible
damage. Apply only the following: (Recommended cleaning agents, paints,
adhesives and the like) as appropriate.
If
the helmet model was certified according to a special addendum to this
standard, each helmet shall also include the warning labels required by that
addendum.
Each
helmet shall also include one of the Foundation's serialized certification
labels. The Snell certification label
shall be placed either inside or on the outside of the helmet, as appropriate,
in such a way that it cannot be removed intact.
The
registered trademark (certification label) of the Snell Memorial Foundation may
be used by the manufacturer only under license from the Snell Memorial Foundation. The specifics of licensure may be obtained
from the Foundation.
MARKING
AND LABELING OF CRITICAL COMPONENTS
If
a helmet component may reasonably be replaced with an inappropriate substitute
that might degrade wearer safety and performance in any of the tests called out
in this standard, the manufacturer must mark those components so that users may
avoid the purchase and use of inappropriate replacement parts. In particular, face shields on full face
helmets must be marked to identify the manufacturer and the month and year of
manufacture.
HEAD FORMS
This
standard invokes six standard head forms for helmet inspection, marking and
testing. The geometry of these head
forms is according to the definitions for the ‘A’, ‘C’, ‘E’, ‘J’, ‘M’, and ‘O’
head forms described in International Standards Organization (ISO) Draft
Standard ISO DIS 6220-1983. The impact
mass specifications for the impact test phase are comparable to those in ECE
22-05 for these same head form designations.
ISO DIS 6220-1983
includes descriptions for half head forms suitable for guided fall impact
testing or for full head forms such as those used in the positional stability
tests. Figures 1 and 2 depict the
general shapes of the half head form configuration. The following table lists useful dimensions
from the two references given above.
|
Table 1 Useful Head Form Parameters |
||||
Head Form |
Circumference |
Mass |
Crown to Basic
Plane |
Basic to Reference
Plane |
A |
50 cm |
3.100 kg ± 100 g |
113.5 mm |
24.0 mm |
C |
52 cm |
3.600 kg ± 100 g |
118.0 mm |
25.0 mm |
E |
54 cm |
4.100 kg ± 100 g |
122.0 mm |
26.0 mm |
J |
57 cm |
4.700 kg ±
100 g |
130.0 mm |
27.5 mm |
M |
60 cm |
5.600 kg ± 100 g |
136.0 mm |
29.0 mm |
O |
62 cm |
6.100 kg ± 100 g |
140.0 mm |
30.0 mm |
EXTENT OF PROTECTION
The extent of
protection corresponds to that region of the head for which protection is
sought.
There are a number of planes fixed
in the geometry of these head forms as shown in Figure 1. This description of the extent of protection
uses the ISO definitions of the basic plane, the longitudinal plane, the transverse
plane and the reference plane. Other
planes have also been defined strictly for convenience and clarity.
The basic plane
corresponds to the anatomical plane (Frankfort plane) that includes the
auditory meatuses and the inferior orbital rims. The reference plane is above and parallel to
the basic plane. The longitudinal or midsagittal plane is perpendicular to the
basic plane and is the plane of symmetry dividing the right half of the head
form from the left. The transverse or
coronal plane is perpendicular to both the longitudinal and basic planes. It corresponds to the anatomical plane that
contains the two auditory meatuses and divides the front from the rear portions
of the head.
These planes are all well known
entities. Several other planes, however,
have proven useful. The S0
plane is parallel to the basic plane and lies above it at a distance determined
by the size of the head form. The S3
plane is parallel to the S0 plane and the basic plane and lies
between them. The S4 plane is
also parallel to these planes and lies below the basic plane.
The rear plane divides the rear
third of the head from the front two thirds.
It is parallel to the transverse plane and lies at a given distance
behind the point where the reference plane and longitudinal planes intersect
with the front surface of the head form.
The distance from this point, hereafter called the reference point, is
determined by the size of the head form.
The fore plane is also parallel to the transverse plane. It lies behind the reference point at a
distance determined by the size of the head form.
Figure 2
Extent of Protection |
Table
2
Extent of Protection |
|||||
Head form
Designation |
Parameters |
||||
a |
b |
c |
d |
e |
|
ISO A |
39.0 mm |
128.6 mm |
26.1 mm |
46.8 mm |
52.2 mm |
ISO C |
40.6 mm |
133.8 mm |
27.2 mm |
48.4 mm |
54.3 mm |
ISO E |
42.2 mm |
139.0 mm |
28.2 mm |
50.0 mm |
56.4 mm |
ISO J |
45.2 mm |
148.4 mm |
30.0 mm |
53.0 mm |
60.0 mm |
ISO M |
47.4 mm |
155.8 mm |
31.5 mm |
55.2 mm |
63.0 mm |
ISO O |
49.2 mm |
161.5 mm |
32.2 mm |
57.2 mm |
64.5 mm |
The extent of
protection provided by the helmet must include the entire region above the S0
plane and forward of the fore plane, the entire region above the S3
plane and between the fore and rear planes and the entire region above the S4
plane and behind the rear plane. Figure
2 and the associated table lay out these additional defined features and show
the extent of protection and the test line.
TESTING
A.
Inspection
Each
helmet will be inspected for the required labels and for compliance with the
general limitations made on structure.
Samples received for certification testing must incorporate all the
critical component labels but other labeling is not necessary for
evaluation. Samples received for RST
(enforcement) testing must have all the required labels.
Some
helmets may incorporate innovations and other features not anticipated by this
Standard but which raise concerns about the safety and effectiveness of the
headgear. These will be referred to
members of the Foundation's Board of Directors for evaluation. Any feature deemed to reduce the protective
capacity of the headgear, whether explicitly mentioned in this Standard or not,
will be a cause for rejection.
B. Head Forms and Helmet Positioning
The
determination of which head forms are appropriate to a helmet is based on the
specified smallest and largest head circumferences for the helmet. For samples submitted for certification, this
specification must include the smallest and largest values of head circumference
for every possible fit pad configuration of the helmet. For helmets received for RST testing, the
smallest and largest head circumferences will be taken directly from the helmet
label.
If the smallest head circumference specified for
the helmet is less than 50 cm, the A head form is the smallest
appropriate. Otherwise, the smallest
appropriate head form for a particular helmet is the largest of the six head
forms whose circumference is no greater than the manufacturer’s specified
smallest circumference. The largest appropriate head form is the largest of the
six specified head forms whose circumference is no greater than the
manufacturer’s specified largest circumference.
Table
3 Test Head Forms as Determined by
Size Specification
|
|||||||
|
Largest Size Specified |
||||||
50 - 51 |
52 - 53 |
54 - 56 |
57-59 |
60 - 61 |
>61 |
||
Smallest Size Specified |
<50-51 |
A |
A,C |
A,E |
A,J |
A,M |
A,O |
52-53 |
|
C |
C,E |
C,J |
C,M |
C,O |
|
54-56 |
|
|
E |
E,J |
E,M |
E,O |
|
57-59 |
|
|
|
J |
J,M |
J,O |
|
60-61 |
|
|
|
|
M |
M,O |
|
>61 |
|
|
|
|
|
O |
If the test samples are determined to be too
small to accommodate the largest head form identified as appropriate, the next
smaller head form shall be considered the largest appropriate. If the samples are too small for even the
smallest appropriate head form as indicated by the manufacture specification,
the samples shall be rejected for certification.
The table shows which head forms will be used in
certification testing for various head size specifications. Since the largest head size should never be
smaller than the smallest head size, most of the lower left region of the table
is blank.
If the size
specification corresponds to one of the light gray cells along the table’s main
diagonal, only a single test head form will be necessary and the manufacturer
need only submit five samples identical samples configured with comfort padding
for the largest intended head size for certification testing. Otherwise, two more samples are required,
identical to the first five in all respects except that the comfort padding
must be configured for the smallest intended head size.
During
testing, helmets will be positioned on the selected test head form according to
the manufacturer’s specified helmet positioning indices. If the manufacturer fails to provide
positioning information with certification samples, the helmets will be
positioned according to the best judgment of the authorized technical
personnel. If the helmets meet
certification requirements, the helmet positioning indices will be those used
in all future testing.
These
helmet positioning indices represent distances on the front of the head form
from the basic plane along the intersection with the longitudinal plane upward to
the lower brow edge of the helmet. Helmet
positioning indices will be assigned for all head form sizes appropriate to the
headgear. Each headgear could
conceivably require as many as six helmet positioning indices, one each for the
‘A’, ‘C’, ‘E’, ‘J’, ‘M’ and ‘O’ head forms.
C. Marking
The
helmet is placed upon the largest appropriate ISO head form, positioned
according to the apposite helmet positioning index and held in place with an
applied force of 50 newtons (11.25 lbs).
The intersections of the shell with the various defined planes are then
traced onto the outer surface of the helmet in the following manner:
The
level of the S0 plane is marked on that portion of the helmet in
front of the fore plane. The level of
the S3 plane is marked on that portion lying between the fore and
rear planes. The level of the S4
plane is marked on that portion behind the rear plane. Finally, line segments along the fore plane
are marked to join the S0 and S3 planes and, similarly,
line segments along the rear plane are marked to join the S3 and S4
planes.
These
lines enclose the top of the helmet and are the boundary of the required extent
of protection. However, it shall not be
a cause for rejection if parts of this boundary fall below the edge of the
helmet. A test line shall be constructed
within the extent of protection 40 mm from the closest point on the boundary as
shown in figure 2.
If
identical helmets are to be configured with different thicknesses of comfort
padding to accommodate different ranges of head size, the required extent of
protection marked on the test samples shall include the required extent of
protection for each different configuration as marked on the largest head form
appropriate for each. That is: the helmet must meet all the requirements of
this Standard in each of the intended configurations.
D.
Peripheral Vision
The
clearance for peripheral vision will be checked by placing the helmet on each
appropriate ISO head form, positioning it according to the apposite helmet
positioning index and holding it in place with a force of 50 newtons. The clearance must include the following
solid angles to the front of the head form:
1.
The upward visual clearance.
2.The
lateral visual clearance.
3.The
downward visual clearance except for the breath deflector allowance.
Helmets
certified to a special addendum to this standard and bearing the warning labels
specified in the addendum will not be subjected to the following procedures and
criteria for evaluating clearances for
vision. However, the procedures
and criteria specified in the addendum will be applied instead.
The
upward visual clearance is the solid angle bounded by the reference plane of
the head form and a second plane tilted 7º up from the reference plane. This second plane intersects the reference
plane at two points on the front surface of the head form that are 31 mm to the
right and left of the longitudinal plane as shown in figure 3.
|
The lateral visual clearance, as shown in figure 4, is the solid angle bounded by the reference plane, the S4 plane and two more planes that are perpendicular to the reference plane and that contain the reference point on the front of the head form. One of these two planes forms an angle of 105º with the longitudinal plane and lies to the left of the head
form. The other forms
the same angle to the right of the head form.
Figure
4 Lateral Visual
Clearance
The
downward visual clearance is the solid angle bounded by the basic plane of the head
form and a second plane tilted 30º down from the basic plane that intersects it
at two points on the front surface of the head form that are 31 mm to the right
and left of the longitudinal plane as shown in figure 5. However, intrusions into this downward
clearance are permitted so long as the intrusions are within the breath
deflector allowance.
|
|
The
breath deflector allowance is shown in figure 6. It includes the region that is within 31 mm
to the right and left of the longitudinal plane and that lies below the two
planes that form 45º angles with the longitudinal plane and that intersect it
at the level of the S4 plane.
Figure 6
Breath Deflector Allowance
E.
Performance
Testing
The
performance testing subjects helmets to a dynamic test of retention system
strength, to a test for positional stability, to impact management tests, to
helmet shell penetration tests, to a removability test, and to chin bar and
face shield tests if appropriate. These
tests are conducted upon helmet samples kept under laboratory ambient
temperature and humidity or that have been conditioned in one of three
environments simulating some of the conditions in which the helmet might
reasonably be expected to be used.
Prior
to conditioning and testing, samples may be exposed to solvents common to
motorsports which have been found to attack and degrade some helmet components.
In
certification testing, four samples are required for testing on the largest
appropriate head form. The first of these
is kept at laboratory ambient temperature and humidity and allowed to come to
equilibrium. It is subjected first to
the positional stability test and then to the impact management and other
tests. The second, third and fourth
samples are conditioned hot, cold and wet, and subjected to the dynamic test of
the retention system, the impact management test and the other tests. If the smallest appropriate head form is not
the same as the largest, two additional samples are required for testing on this
head form. The first of these will be
allowed to stabilize at laboratory ambient temperature and humidity and then
will be subjected to the test for positional stability. This sample may then be conditioned hot or
cold or kept at laboratory ambient for impact testing. The second additional sample shall be tested
in impact conditioned hot, cold or wet or kept at lab ambient according to the
best judgment of the test personnel.
The
selection of tests, conditioning and special conditioning is left to the
discretion of the Foundation's technical personnel. However, for certification testing, each of
the specified tests shall be applied to at least one sample. Furthermore, it is expected that all testing
will be conducted so as to exercise all the likely failure modes of the helmet.
E1. Conditioning for Testing
Test
samples may be kept at laboratory ambient temperature and humidity or may be
conditioned cold, hot or wet according to the specifications given below. At the discretion of the Foundation's
technical personnel and at any point during the testing, a sample previously
kept at ambient may be conditioned cold, hot or wet. However, once a sample has been conditioned
cold, hot or wet, the sample must be maintained in that condition throughout the
rest of the testing.
The
special solvent wipe conditioning described below may be applied to any sample
at the discretion of the Foundation's technical personnel.
a.
Special Conditioning. Prior to any impact or retention system
testing helmets may first be conditioned with a solvent mix of 50% toluene and
50% isooctane. A cotton cloth or
suitable substitute shall be soaked in the solvent and used as an
applicator. The solvent will be applied
to the shell first in an area within 5 mm of the chin strap attachments for not
less than five (5) seconds on each side and then applied to the remainder of
the shell for not less than ten (10) seconds.
At least thirty minutes shall elapse before further conditioning and testing.
b.
Cold. The sample shall be conditioned by being
exposed to a temperature of -20 ±2º C for a period of not less than four (4)
hours, or more than twenty-four (24) hours.
c.
Heat. The sample shall be conditioned by being
exposed to a temperature of 50 ±2º C for a period of not less than four (4)
hours, or more than twenty-four (24) hours.
d.
Wet. The
sample shall be conditioned by being continuously sprayed with water at a
temperature of 25 ±5º C for a period of not less than four (4) hours, or more
than twenty-four (24) hours. This spray
shall be directed at the helmet's external surfaces. The helmet shall not be subjected to total
immersion.
All testing of these hot, cold and wet helmets
shall begin within two (2) minutes from the time of removal from the
conditioning apparatus. The samples
shall be returned to the conditioning apparatus between tests.
E2. Positional Stability (Roll-Off)
The
test for positional stability shall only be applied to samples kept at ambient
laboratory temperature and humidity. The
helmet shall not have been subjected to any prior performance testing.
The
helmet shall be tested on the smallest appropriate standard full-face head form. The head form shall be supported on a stand
so that its vertical axis points downward at an angle of 135º to the direction
of gravity. The head form shall be
oriented face down. The helmet shall be
placed on the head form and adjusted to obtain the best configuration of the
retention system. An inelastic strap
shall be hooked to the edge of the helmet at the rear centerline and brought
forward so that its free end hangs downward across the top of the helmet. An inertial hammer shall be suspended from
the free end of the strap. This inertial
hammer shall enable a 4.0 kg ±50 g mass to be dropped through a 0.6 m guided
fall in order to deliver an abrupt shock load to the headgear. The shock load will force the helmet to
rotate forward on the head form. The
helmet may be shifted but must remain on the head form.
The
head form shall be repositioned so that it is facing upward but with the
vertical axis still oriented downward at 135º to gravity. The helmet shall be positioned and adjusted
to obtain the best configuration of the retention system. The strap/inertial hammer shall be hooked to
the brow edge of the helmet at the center line so that the strap lies along the
centerline and the hammer is suspended from the top of the helmet. The shock weight shall be dropped through the
0.6 m guided fall delivering an abrupt shock load forcing the helmet to rotate
rearward. The helmet may be shifted but
must remain on the head form.
The
entire portion of the inertial hammer assembly that participates in the loading
of the helmet shall be such that its mass is no more than 5.0 kg including the
4.0 kg shock mass.
E3. Dynamic
Test of Retention System
The
dynamic test of the retention system may be applied to any sample either kept
at ambient temperature and humidity or conditioned hot, cold or wet. This test may be performed before, after, or
between any of the other procedures in the test sequence. However, the retention test shall not be
valid if an integral chin bar has been removed from a full face helmet.
The
helmet shall be supported on its lower shell edge in such a manner that the
chin strap may be fastened under a device whose upper end approximates the
contour of the bony structure of the jaw.
The device will then be given a mechanical pre-load followed by a
dynamic loading. The retention system
fails if it cannot support the mechanical loads or if the maximum deflection
during the dynamic load exceeds 30 mm.
The retention system also fails if it cannot be easily and quickly
unfastened after testing.
If
the technician determines that the helmet cannot be adequately supported on its
lower shell edge, at his discretion, he may support the helmet on a head form
for this test.
a. This chinstrap loading device
shall consist of a simulated jaw and accommodations for the pre-load and
dynamic load. The jaw portion shall
consist of two metal bars or rollers, each one 12.7 ±0.5 mm in diameter,
separated by 76 ±0.5 mm on center. The
mass of this device shall not exceed 6.0 kg.
b.
A pre-load shall be applied for at least 60
seconds. This pre-load plus the mass of
the chinstrap loading device shall total 23 kg±500 g.
c. A 38 kg±500 g mass shall be dropped in a vertical guided
fall a distance of 120 mm so as to load the retaining system abruptly; the 38
kg mass and pre-load mass shall not be additive. In order to protect the test mechanism, the
impact of the 38 kg mass may be cushioned with a 00-93 durometer rubber pad 150
mm in diameter by 6½
mm thick, or its equivalent.
E4. Impact Management Tests
The
impact management tests may be performed on samples kept at ambient temperature
and humidity or conditioned hot, cold or wet.
The sample shall not have been subjected to the shell penetration test
beforehand.
These
tests involve a series of controlled impacts in which the helmet is positioned
on a test head form. The helmeted head
form is then dropped in guided falls onto specified test anvils. The impact site and the impact energy must
meet certain requirements in order for the tests to be valid.
If
the sample is so constructed that it interferes with the test equipment
preventing impacts at sites within the test line, then, at the discretion of
the Foundation's technical personnel, parts of the helmet may be cut away to
facilitate testing. Every reasonable
effort to minimize such cutting will be made.
However, there shall be no relaxation of the impact levels or of the
test criteria.
Certain tests shall not be valid
when performed on samples that have been cut for impact testing: the dynamic
strength of retention system test of section E3., the positional stability test
of section E2., the chin bar test of section E5. and the removability test of
section E8.
Special considerations apply when the helmet is a “flip-up”
model, that is: configured with a chin bar that pivots up and away from the
face of the wearer. Whenever possible,
the impact tests will be performed with the chin bar locked in the closed
position. In these tests, in addition to
all the other test criteria, the chin bar must not release and “flip-up”
inadvertently.
E4.1 Impact Management Test Equipment
The
test equipment shall consist of at least the following items:
a. The smallest and largest of the head forms appropriate for the helmet
sample. This head form shall be of
rigid, low resonance metal such as magnesium alloy and shall conform to the 'A',
'C', 'E', 'J', 'M' or 'O' geometries specified in ISO DIS 6220‑1983.
b. A ball‑arm/collar assembly which is fitted to a socket machined
into the base of the head form. The
ball/socket configuration shall be such that the geometrical center of the ball
is located on the central vertical axis of the head form 12.7 mm above the
reference plane as described in ISO DIS 6220-1983. The ball-arm/collar assembly shall also
include a uniaxial accelerometer fixed firmly into the ball.
c. A head form support assembly rigidly attached to the ball-arm. This support assembly shall be such that it
and consequently the head form may be guided in a vertical drop. The mass of this support assembly shall not
exceed 1.2 kg. The total mass of the
head form plus ball-arm/collar assembly plus head form support assembly shall
be within 100 grams of: 3.1 kg for the ISO A head form, 3.6 kg for the ISO C
head form, 4.1 kg for the ISO E head form, 4.7 kg for the ISO J head form, 5.6
kg for the ISO M head form and 6.1 kg for the ISO O head form.
d. A guidance system such that the head form/support assembly is guided
in a vertical drop onto a test anvil.
This guidance system may consist of two or more wires or one or more
rails. The head form/support - guidance
system - test anvil alignment shall be such that:
d1. The drop
trajectory shall be a straight line within 3º of vertical and within 5º of the
sensitive axis of the uniaxial accelerometer.
d2. The line
parallel to the drop trajectory and passing through the center of the head form
ball-socket shall pass within 5 mm of the center of the test anvil, within 10
mm of the center of gravity of the head form/support assembly, and within 5 mm
of the sensitive element of the uniaxial accelerometer.
e. A rigid anvil mount consisting of a solid mass of at least 500
kg. The upper surface of the anvil mount
shall consist of a steel plate with a minimum thickness of 12 mm and a minimum
surface area of 0.10 m2.
f. Three test anvils: flat, hemispherical and edge.
f1.
The flat anvil shall have a
minimum surface area of 0.0127 m2, e.g. 127 mm diameter face. When fixed in position on the anvil mount,
the surface shall be perpendicular to the head form trajectory.
f2. The
hemispherical anvil shall have a 48 ±0.5 mm radius.
f3. The edge
anvil shall have a striking face 6.3 mm wide with a depth of at least 35
mm. The radius of the edges on the
impact face shall not exceed 0.5 mm. When
in position, the striking face shall be perpendicular to the head form
trajectory. The anvil shall be
sufficiently long that the ends do not contact the helmet during impact.
g. A uniaxial accelerometer. The acceleration data channel must comply
with SAE recommended practice J 211 requirements for channel class 1000 with
the exception that the frequency response need not include the range from dc to
10 hz which may not be obtainable using certain types of transducers.
h. A velocity measurement device which will yield
the velocity of the head form/support assembly within the last 40 mm of travel
before impact. The velocity measurement
must be accurate to within ±1%.
E4.2 Test Definitions
a. The impact site refers to the portion of the helmet struck during an
impact test. It is defined as the point
where a line passing through the center of the head form ball and the center of
the anvil intersects the outer surface of the helmet at the instant the helmet
first touches the anvil.
b. The impact velocity is the velocity of
the head form/support assembly as measured within no more than 4 cm of the
first contact between the helmet and the impact surface.
c. This standard specifies nominal impact
velocities which must be adjusted in order to allow for deviations between the actual
mass of the test head form assembly and the specified ideal value. The actual test impact velocity shall be the
specified nominal velocity multiplied by the square root of the value obtained
by dividing the ideal head form assembly mass by the actual mass. For example, if, for the ‘A’ head form, the
mass of the head form plus ball-arm/collar and support assembly as in paragraph
E4.1c masses 3.2 kg instead of the ideal mass of 3.1 kg, the test impact
velocities shall be obtained by multiplying the nominal velocities by a factor
of 0.984.
d. There are two levels of test: the first is the
standard level used to identify those helmets which definitely meet this
standard. It is applied to samples
submitted for certification testing and to those acquired for the Foundation’s
random sample test (RST) program. The
second is the deviation level which is applied to samples acquired for second
round RST procedures, that is: testing of samples of currently certified models
for which previous samples have obtained failing results in RST testing. Failure to meet test criteria at the
deviation levels indicates that the sample definitely does not meet the
requirements of the standard.
E4.3 Test
Impacts
Test
impact sites shall be on or above the test line. Rivets, vents and any other helmet feature
within this region shall be valid test sites.
Each impact site will be subjected to a group of one or two impacts
according to the anvil selected for that site.
The
impact site for the first impact within in a group is the target for the
successive impacts in the same group.
However, if an impact group is sited closer than 120 mm to any previous
impact group, that later impact shall be declared invalid.
There
is no restriction regarding test anvil selection. The impact velocities for each test impact
depend on the type of test and on the head form designation. Second impacts do not apply to helmets in
tests against the edge anvil.
The
technician may select either the largest or smallest appropriate head form for
any particular group of impacts. In all
cases the technician may impact any site on the helmet surface on or within the
test lines as drawn for any of the head forms considered appropriate for that
helmet.
The
nominal impact velocities are listed in the following table:
Table 4 Nominal Impact Velocity Table |
|||||||
All Anvils |
Head Form |
||||||
A |
C |
E |
J |
M |
O |
||
Certification |
1st |
7.75 m/s |
7.75 m/s |
7.75 m/s |
7.75 m/s |
7.75 m/s |
7.75 m/s |
2nd |
7.09m/s |
7.09 m/s |
7.09 m/s |
6.78 m/s |
5.73 m/s |
5.02 m/s |
|
Deviation |
1st |
7.48 m/s |
7.48 m/s |
7.48 m/s |
7.48 m/s |
7.48 m/s |
7.48 m/s |
2nd |
6.85 m/s |
6.85 m/s |
6.85 m/s |
6.55 m/s |
5.54 m/s |
4.84 m/s |
a.
Each site tested against the flat anvil shall be tested according to the values
in the impact velocity table adjusted for the mass of the head form assembly.
b.
Each site tested against the hemispherical anvil shall be tested according to
the values in the impact velocity table adjusted for the mass of the head form
assembly.
c.
Each site tested against the edge anvil shall be tested according to the values
in the impact velocity table adjusted for the mass of the head form assembly. No helmet shall be subjected to the second
impact for this anvil.
d. If the impact velocity for
any test impact exceeds the specified mass adjusted velocity by more than 1.5%,
that impact shall be declared invalid.
Please
Note: The impacts described above are based on specific velocities and not
prescribed drop heights. To attain the
proper velocity for an impact, it is likely that the drop height will need to
be adjusted to compensate for frictions inherent in most mechanical helmet
testing systems. Height adjustments for these frictions should not account for
more than 10% of the total drop height.
Also, the 1.5% margin allowed for impact velocity reflects the
uncertainties expected even for well maintained drop equipment. It is expected that drop heights will always
be selected to produce, as closely as possible, the precise impact velocity as called
out in the standards and adjusted for head form assembly drop mass..
E4.4 Impact Test Interpretation
Table 5 Peak Acceleration Criteria |
||||||
|
Head Form |
|||||
A |
C |
E |
J |
M |
O |
|
Certification |
275 G |
275 G |
275 G |
275 G |
264 G |
243 G |
RST |
285 G |
285 G |
285 G |
285 G |
273 G |
251 G |
The
peak acceleration of the head form shall not exceed the values in the table
above depending on the head form and the type of test. The helmet’s protective structures shall not
break apart throughout the testing. If
the Foundation's technical personnel conclude that fracture of the helmet
shell, impact liner, retention system or other components could reasonably
imply an undue laceration hazard either from the impact surface or from the
helmet itself, the sample shall be considered to have failed. A flip-up configuration tested with the chin
bar closure locked at the outset of a valid impact and which releases inadvertently
as a result of the impact will also be deemed to have failed.
If,
in certification testing, a sample is found to meet all the test criteria but
any two of the impacts were at less than 98.5% of the specified impact velocity
as adjusted for drop assembly mass, the testing for that sample shall be
declared inconclusive and must be repeated.
Similarly, if there are two instances where an impact falls beyond 10 mm
from the first impacts in its group, the testing for the sample shall be
declared inconclusive and must be repeated.
Finally, if an invalid impact produces a peak acceleration exceeding the
test criterion, the testing for the sample shall be declared inconclusive and
must be repeated.
The
impact test procedures leave considerable latitude to the helmet tester
regarding site and anvil selection. It
is expected that the tester will orchestrate each standard test series in order
to investigate potential weaknesses and to exercise each likely failure mode
and will conduct deviation level testing to exercise the failure modes
identified previously.
If
at the end of a certification test series, the Foundation's technical personnel
conclude that the results obtained in valid impacts are not sufficient to
determine whether the helmet model meets the performance requirements of this standard,
additional samples may be conditioned and tested. It is expected that all samples submitted
will meet all the test requirements.
E5. Chin Bar Test
The
chin bar test applies to full face helmets only. At least one helmet in each certification
series shall be tested. The helmet shall
be firmly mounted on a rigid base so that the chin bar faces up and the
reference plane is at 65 ±5º from horizontal.
A mass of 5 ± .2 kg with a flat striking face of 0.01 m5 minimum area shall be dropped in a guided fall
so as to strike the central portion of the chin bar with an impact velocity of
3.5 ±0.2 m/sec. The maximum downward
deflection of the chin bar must not exceed 60 mm nor shall any component fail
so as to cause a potential injury to the wearer.
E6. Shell Penetration Test
The
shell penetration test may be applied to helmets kept at laboratory ambient
temperature and humidity or helmets conditioned hot, cold or wet. At least one
helmet sample shall be tested in shell penetration. The complete helmet shall be placed on a
rigidly mounted head form. The test head
form for the penetration test need not be the standard ISO head form shape used
in the impact testing and helmet marking.
It is expected only that the device used will provide reasonable support
for the helmet and conformance with the interior of the helmet immediately
beneath the site of the penetration test.
If the helmet contains a sling or some other adjustable sizing
component, it shall be relaxed to its most extendable position.
The
penetration test striker shall have a mass of 3 kg ±50 g. The striker shall fall through a height of 3
m ±15 mm. The point of the striker shall
be a cone with an included angle of 60º ±0.5º and an altitude of 38 ±0.38
mm. The striking tip shall have a
hardness of 60 Rockwell (scale C ± 3 points) and a radius of 0.5 ± 0.1 mm.
The
test striker may be directed at any site on or above the test line but the
penetration test site must be at least 7.5 cm removed from the center of any
impact test site or any other penetration test site. At the test technician’s discretion, samples
may be tested at more than one site on the shell.
For all penetration tests performed,
the test striker must not penetrate to achieve even momentary contact with the
test head form.
E7. Face
Shield Penetration Test
If
a face shield is provided with a full face helmet, this face shield shall be
tested for penetration resistance in the following manner:
The
face shield shall be tested on the appropriate helmet, correctly deployed
across the facial opening and under laboratory ambient conditions. A soft lead pellet weighing 1 ±0.1 g with a
diameter of 5.5 ±0.1 mm and traveling at a velocity of 500 ±20 km per hour
shall strike the face shield normal to the surface. The face shield shall be tested in at least
three different locations: the center
line and 80 ±5 mm to either side of the center line. The pellet must not penetrate to the interior
of the helmet.
E8. Removability
The
helmet removability test determines whether the helmet can be removed from an
unconscious victim without resorting to any buckles, clasps or other mechanisms
which may be rendered non-functional by impact stresses. The helmet is placed on the largest
appropriate complete ISO head form with all the closures and retention systems
engaged. A technician must remove the
helmet from the head form using simple, common hand tools but without accessing
any of the helmet mechanisms.
The
hand tools for this test are limited to shears, simple edged tools and flat
bladed screw drivers. The operation must
not require more than thirty seconds.
E9. Post-testing Disassembly and Inspection
If
a set of helmets is submitted for and passes certification testing, at least
one of the tested samples shall be disassembled and inspected. If the laboratory staff identifies any
internal feature that is not plausible for inclusion in a production helmet,
the model shall be rejected. If an
internal projection on the helmet shell is deemed to present an undue
laceration or puncture hazard, the model shall be rejected. In evaluating these internal projections, no
allowance shall be made for liner thickness.
At
the discretion of the technician, any helmet may be disassembled in order to
check for internal projections, plausibility or for deviations from the
originally certified configuration.