Young children are at special risk from air bags because, when unbelted, they are easily propelled close to the air bag as a result of pre-crash braking. NHTSA strongly recommends that young children ride in the back seat, which is a much safer location whether or not a vehicle has air bags.
In order to address the risks air bags pose to young children who do ride in the front seat, NHTSA is proposing requirements using both 3-year old and 6-year old child dummies. While there are both similarities and overlap between the requirements using the different dummies, the agency will discuss them separately (and cover them separately in the proposed regulatory text) because a manufacturer might choose to select different compliance options for the two dummies.
As to 3-year-old child dummies, the agency is proposing four alternative test requirements, the selection of which would be at the option of the manufacturer. The four manufacturer options are: (1) test requirements for an air bag suppression feature that suppresses the air bag when a child is present, i.e., a weight or size sensor, (2) test requirements for an air bag suppression feature that suppresses the air bag when an occupant is out of position, (3) test requirements for low risk deployment involving deployment of the air bag in the presence of out-of-position 3-year old child dummies, and (4) full scale dynamic out-of-position test requirements, which include pre-impact braking as part of the test procedure.
NHTSA is proposing to specify use of the Hybrid III 3-year-old child dummy. The motor vehicle industry is familiar with this dummy, and the agency expects to propose adding it to Part 572 later this year.
Requirements for an air bag suppression feature (weight or size sensor) that suppresses the air bag when a child is present. These requirements would mirror those being proposed with respect to a suppression feature for infants in rear facing child seats. If this option were selected, the air bag would need to be deactivated during several static tests using, in the right front passenger seat, a 3-year old child dummy, and also during rough road tests.
The child dummy would be placed in a variety of different positions during the static tests. Because the effectiveness of such a feature depends on the air bag being suppressed regardless of how a child may be positioned, and given the ease of conducting such tests, the agency is specifying a relatively large number of such positions. Some of the positions specify placing the dummy in a forward-facing child seat or booster seat.
In order to ensure that the suppression feature does not inappropriately suppress the air bag for small statured adults, the air bag would need to be activated during several static tests using a 5th percentile adult female dummy in the right front passenger seat, and also during rough road tests using that dummy. A manufacturer would also be required to provide a telltale light on the instrument panel which is illuminated whenever the passenger air bag is deactivated and not illuminated whenever the passenger air bag is activated.
Test requirements for an air bag suppression feature that suppresses the air bag when a child is out-of position. The agency believes that a suppression feature that suppresses the air bag when an occupant is out-of-position would need to be tested very differently than one which suppresses the air bag whenever a child is present. While various static and rough road tests can be used to determine whether the latter type of suppression device is effective, they would be of limited utility in testing a feature that suppresses the air bag when an occupant is out of position. This is because one of the key criteria in determining whether the latter type of suppression feature is effective is whether it works quickly enough in a situation where an occupant is propelled out of position as a result of pre-crash braking (or other pre-crash maneuvers) before a crash. The agency has accordingly developed separate test requirements for such devices.
If this option is selected by the vehicle manufacturer, the manufacturer would be required to provide a telltale indicating whether the air bag was activated or deactivated. Operation of the suppression feature would be tested through the use of a moving test device which would be guided toward the area in the vehicle where the air bag is located.
This test device would begin its course of travel in a forward direction toward a target area inside the vehicle. This target area, the air bag suppression zone, consists of a portion of a circle centered on the geometric center of the vehicle's air bag cover. The function of the air bag suppression system would be tested through the use of a headform propelled toward the air bag suppression zone at any speed up to 11 km/h (7 mph)--equivalent to a typical speed that the head of an occupant attains in pre-crash braking. When the test fixture enters the area near the air bag--the air bag suppression zone--where injuries are likely to occur if the air bag deploys, the telltale is monitored to determine if the suppression feature has disabled the air bag.
Apparatus that could be used to conduct this test would include a pneumatically operated ram whose stroke is sufficient to propel a 165 mm (6.5 inch) headform from a point of origin to a point forward of the automatic suppression plane of the test vehicle. Once activated, the pneumatic ram will propel the headform toward the air bag at up to 11 km/h (7 mph). The test headform consists simply of a 165mm (6.5 inch) outside diameter hemispherical shell. This headform is not instrumented nor is it intended to impact with the interior of the vehicle. Therefore, the agency is not specifying that it have a particular mass in an effort to provide maximum flexibility in configuring a test apparatus.
The automatic suppression plane of the vehicle, the point at which the air bag suppression feature must be activated when the plane is crossed by the headform, is located at that point rearward of the air bag and forwardmost of the center of gravity of the head of a seated occupant which the manufacturer determines to be that point where, if the air bag is deployed, a 3-year-old child dummy would meet specified injury criteria.
NHTSA notes that the test procedure it is proposing for air bag suppression features that suppress the air bag when an occupant is out-of-position is similar to one developed by GM. The agency is placing a copy of the GM procedure in the docket.
The agency requests comments as to whether the proposed test procedure would accommodate air bag suppression systems under development. In particular, the agency requests comments as to whether these suppression systems would "recognize" the test device. Additional questions concerning this proposed test procedure are included in a section titled "Questions" later in this notice.
Static tests involving deployment of the air bag in the presence of out-of-position 3-year old child dummies. If the low risk deployment option were selected, a vehicle would be required to meet specified injury criteria when the passenger air bag is deployed in the presence of out-of-position 3-year-old child dummies. Because this test is relatively difficult to run (it requires deployment of an air bag), the agency is proposing that it be conducted at two positions which tend to be "worst case" positions in terms of injury risk. The agency is also proposing more detailed positioning procedures for these two tests than for many of those proposed for the static suppression tests, since injury measures may vary considerably with position. The agency is proposing injury criteria appropriate for a 3-year-old child.
In the case of air bags with multiple inflation levels, the injury criteria would need to be met only for the levels that would be deployed in lower severity crashes, e.g., crashes of 32 km/h (20 mph) or below. The agency notes that while an infant in a rear facing child seat would always be extremely close to the passenger air bag, this is not true for older children. An older child would most likely be extremely close to the air bag in lower severity crashes, following pre-crash braking. Of the 46 older children NHTSA has confirmed as having been killed by a passenger air bag, 38, or 83 percent, were in crashes with a delta V of 24 km/h (15 mph) or below, and all were in crashes with a delta V of 32 km/h (20 mph) or below.
NHTSA requests comments concerning the threshold below which air bag deployment levels should be required to meet injury criteria and above which the injury criteria would not apply. The agency also requests comments concerning test procedures.
Full scale dynamic out-of-position test requirements, which include pre-impact braking as part of the test procedure. Under this option, a vehicle would be required to meet injury criteria in a rigid barrier crash test that included pre-impact braking as part of the test procedure, using an unrestrained 3-year-old child dummy.
Pre-crash braking would be simulated by a vehicle, initially accelerated to the predetermined pretest speed, that is retarded by application of a suitable pre-crash deceleration prior to contact with the rigid barrier. The agency believes that a 24 km/h (15 mph) impact speed with the rigid barrier would generate the crash pulse necessary to evaluate occupant crash protection to the out-of-position occupant. Further details on this alternative test procedure are set forth in the proposed regulatory text (see proposed S29 and S30 for Standard No. 208).
The agency is requesting comments on what impact speed should be specified, as well as on other aspects of the test procedure for this requirement, including dummy seating procedures. Depending on the comments, the agency may modify the test speeds, dummy seating procedures, or other aspects of the test procedure for the final rule.
