Interpretation ID: ACSBcmc

[ ]

Dear [ ]:

This responds to your letter in which you asked about the applicability of Federal motor vehicle safety standards (FMVSSs) to an auxiliary child shoulder belt system (ACSB) for use with belt positioning boosters. Specifically, you ask whether the ACSB would be regulated as a Type 2a shoulder belt or as a child restraint system. As explained below, the ACSB would be regulated as a Type 2a shoulder belt.

Background

Your letter states that the ACSB would be an add-on shoulder belt that would allow the use of belt positioning boosters at seating positions equipped with lap belts only. You state that:

The add-on shoulder belt would be equipped with a standard buckle and length adjustment. It would easily attach to the lap belt buckle, and hook onto the standard top tether anchor for the rear outboard seating position using a standard tether hook.

You also state that the add-on shoulder belt would be recommended for children between 50 and 80 pounds. The add-on shoulder belt would not be originally installed in vehicles but would be provided as an aftermarket product.

By way of background, the National Highway Traffic Safety Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under 49 U.S.C. Chapter 301, manufacturers are required to ensure that their vehicles and equipment meet applicable requirements. The following represents our opinion based on the facts you provided in your letter, and addresses some or all of the specific issues you raised. If we have not addressed an issue, you should not assume that we have concurred with a position you have expressed on that issue.

Your letter asks about the applicability of four standards; FMVSS No. 208, Occupant crash protection, FMVSS No. 209, Seat belt assemblies, FMVSS No. 210, Seat belt assembly anchorages, and FMVSS No. 213, Child restraint systems. I have addressed each standard below.

FMVSS Nos. 208 and 210

Your assertion that FMVSS Nos. 208 and 210 would not apply to the ACSB is correct. FMVSS Nos. 208 and 210 apply, with certain exceptions that are not relevant to this product, to vehicles and not directly to items of equipment. Because the ACSB would not be part of the vehicle as manufactured or sold, FMVSS Nos. 208 and 210 would not be applicable. However, please note that any commercial business that would install this product would be subject to the provisions of 49 U.S.C. 30122(b), which provides that:

No manufacturer, distributor, dealer, or motor vehicle repair business shall knowingly make inoperative, in whole or in part, any device or element of design installed on or in a motor vehicle or item of motor vehicle equipment in compliance with an applicable Federal motor vehicle safety standard.

None of the above named businesses would be able to install this product if installation would cause the vehicle to no longer comply with an FMVSS.[1]

FMVSS No. 209

Under FMVSS No. 209, the add-on shoulder belt would be classified as a Type 2a shoulder belt. Unlike FMVSS Nos. 208 and 210, FMVSS No. 209 is an equipment standard and applies to all seat belt assemblies regardless of whether the seat belts are originally installed in a vehicle or installed after the vehicle has been purchased.

FMVSS No. 209 defines a Type 2a shoulder belt as an "upper torso restraint for use only in conjunction with a lap belt as a Type 2 seat belt assembly."[2] As you state in your letter, this product would provide upper torso restraint and would be intended for use in conjunction with a lap belt only, making it a Type 2a shoulder belt. Type 2a shoulder belts are generally not permitted as original equipment under FMVSS No. 208.[3] However, this general prohibition under FMVSS No. 208 is a vehicle standard and does not prohibit the sale of Type 2a shoulder belts as aftermarket equipment.

You would be required to certify that the ACSB complies with the applicable sections of FMVSS No. 209. Under S4.1(c) of FMVSS No. 209, a Type 2a shoulder belt is required to "comply with applicable requirements for a Type 2 seat belt assembly in S4.1 to S4.4, inclusive." While only those requirements raised by your letter are discussed below, keep in mind that the ACSB would be required to comply with all of the applicable requirements in S4.1 through S4.4.

S4.1 Requirements

S4.1(f) Attachment hardware

Type 2a seat belt assemblies have specific hardware requirements under FMVSS No. 209. However, because of the design and the intended manner of use of the ACSB, it would not be required to provide the attachment hardware specified under S4.1(f) of FMVSS No. 209. S4.1(f) requires that a seat belt assembly must include:

all hardware necessary for installation in a motor vehicle in accordance with Society of Automotive Engineers Recommended Practice J800c, "Motor Vehicle Seat Belt Installation," November 1973. However, seat belt assemblies designed for installation in motor vehicles equipped with seat belt assembly anchorages that do not require anchorage nuts, plates, or washers, need not have such hardware, but shall have 7/16-20 UNF-2A or 1/2-13UNC-2A attachment bolts or equivalent metric hardware.

Because the attachment hardware required under S4.1(f) is needed for permanent installation of the seat belt assembly in a motor vehicle, we interpret S4.1(f) to apply only to seat belt assemblies designed for permanent installation. In this instance, the ACSB is designed to attach to a vehicles existing tether anchorage with the tether hook supplied with the ACSB, allowing for installation when a belt-positioning booster is placed in a seating position that has a lap belt. (The requirements for the tether hook are discussed later in this letter regarding S4.3.) Additionally, in the past we have not required seat belt buckles to comply with requirements that are obviously inapplicable.[4] Because the ACSB is not designed for permanent installation, it would not have to comply with the hardware requirements of S4.1(f) of FMVSS No. 209.

S4.1(g) Adjustment

The add-on system would not have to be certified as complying with the adjustment requirements of S4.1(g) of FMVSS No. 209, which requires Type 2a seat belt assemblies to be capable of fitting up to the dimensions of a 95^th percentile adult male. S4.1(g) contemplates seat belt assemblies that would be permanently installed in motor vehicles. Permanently installed belts need to fit a wide range of occupants. Conversely, the ACSB would be recommended for use only with a booster seat and only for children weighing between 50 and 80 lb. Because of this limited and specific recommended use, the ACSB would not be required to comply with the adjustment requirements of S4.1(g) of FMVSS No. 209. However, as discussed below, the ACSB must be labeled with information about the size of the occupants for whom it is intended.

S4.1(k) Installation instructions and S4.1(l) Usage and maintenance instructions

S4.1(k) and S4.1(l) of FMVSS No. 209 require appropriate installation and use instructions to be provided with the add-on shoulder belt. S4.1(k) requires the ACSB to be accompanied by an instruction sheet providing sufficient information for its proper installation. As such, in this case these instructions would have to including a statement that the assembly is for installation only in motor vehicles with an upper tether attachment point that meets the applicable requirements of FMVSS No. 225. S4.1(l) requires that written instructions on proper use accompany the assembly. Because proper use of the ACSB would only be with a booster seat and only for children up to 80 lb, the instructions would be required to specify as such. Also under S4.1(l), a warning would have to be provided stating that the system is not to be used without a lap belt or by occupants weighing over 80 pounds. In addition, we suggest that you consider placing warning labels on the belt to inform occupants of the weight and use restrictions.

S4.2 Requirements for Webbing

FMVSS No. 209 establishes several requirements for the webbing used in a Type 2a shoulder belt. These include width, strength and elongation requirements.

S4.2(a) Width

S4.2(a) establishes a minimum width for specific portions of webbing in a seat belt assembly, including a Type 2a belt. Seat belt assembly webbing must be a minimum of 46 mm in width, except for portions that do not touch a 95^th percentile adult male. S4.2(a) ensures that belt webbing coming into contact with an occupant spreads the load imposed by the belt in a crash. By requiring webbing to spread rather than concentrate the load, the belt width requirement helps minimize the possibility of webbing-caused injury. The shoulder belt portion of the add-on belt meets the minimum width, but the attachment webbing for the add-on buckle is of narrower width.

You state that the narrower webbing is not intended to apply restraint force to the occupant and is of a short, non-adjustable length. If the narrower webbing would not apply restraint force to the occupant, then the webbing need not meet the minimum width requirement.

S4.2(b) Breaking strength and S4.2(c) Elongation

You state that the ACSB buckle is attached to the lap belt with a short loop of 25 mm wide webbing. You concluded that because the ACSB buckle webbing would be used solely as a loop in the assembly, the strength and elongation requirements should be applied to the webbing as a loop and not to a single piece of webbing. We disagree. After the ACSB buckle is attached to the vehicles lap belt, it would be possible for the ACSB buckle attachment to experience a substantial portion of the loading along a single piece of webbing, not the loop. If the webbing were to break at a point on a single strap, the anchoring could fail. In addition, the load may not be distributed equally across both sections of the loop. One section could experience a higher load than the other. Because of these potential consequences, the strength and elongation requirements of S4.2(b) and S4.2(c) would be applied to a single piece of the ACSB buckle webbing and not to the webbing as a loop.

S4.3 Requirements for Hardware

S4.3(c) Attachment hardware

The tether hook used to anchor the add-on shoulder belt to the tether anchorage at an adjacent seating position would be considered a "quick-disconnect" type of attachment hook under FMVSS No. 209 and would be required to meet certain strength requirements. The tether hook is a single hook and would be capable of quickly connecting to, and disconnecting from, the tether anchorage, which acts as an eye bolt. Under S4.3(c)(3) of FMVSS No. 209, seat belt assemblies having single attachment hooks of the quick-disconnect type for connecting webbing to an eye bolt shall be provided with a retaining latch or keeper ("keeper"). "Keepers" must be certified as not moving more than 2 millimeters (mm) in either the vertical or horizontal position when force is applied as specified in S5.2(c)(3). The "keeper" requirements ensure that the attachment hardware does not disconnect when loaded. Because the tether hook used with the add-on belt would function as a quick-disconnect type of attachment hook for a Type 2a seat belt, the tether hook spring clip would be required to comply with the "keeper" strength requirements under FMVSS No. 209.

FMVSS No. 213

In your letter, you ask if the add-on shoulder belt would be defined as a child restraint system (CRS) under FMVSS No. 213 if it were recommended for children between 40 and 80 lb. Because this assembly would be a Type 2a assembly, it would be excluded from the definition of a CRS. S4 of FMVSS No. 213 defines a CRS as any device, except a Type 1 or Type 2 seat belt, designed for use in a motor vehicle or aircraft to restrain, seat or position children who weigh 50 lb or less.[5] (Emphasis added.) The add-on shoulder belt is intended for use in conjunction with a lap belt. Under the intended use, the entire assembly would provide pelvic and upper torso restraint and function as a Type 2 seat belt assembly. As a component of a Type 2 assembly, this product would not be a CRS under FMVSS No. 213. We note that while the ACSB is currently excluded from the definition of a CRS, Antons Law (Pub. L. No. 107-318; 2002) requires NHTSA to consider whether to include injury performance criteria for booster seats "and other products for use in motor vehicles for the restraint of children weighing more than 50 pounds" under FMVSS No. 213.

In closing, the agency encourages approaches that may increase the use of child restraint systems, provided that the approaches comply with all applicable Federal motor vehicle safety standards and do not compromise the safety of motor vehicle occupants. As with any product that is designed to attach to an existing device on a vehicle, we urge you to consider ways to reduce the likelihood of misuse of the product. Further, the use of an additional buckle on a product used to restrain children could increase the difficulty in releasing the child in an emergency situation. We appreciate your concern in thoroughly considering these and all other safety issues.

If you have any other questions please contact Chris Calamita of my staff at this address or at (202) 366-2992.

Sincerely,

Jacqueline Glassman
Chief Counsel

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d.4/8/03