Mr. Gary R. Greib
Manager, Product Investigations and Safety Affairs
5825 Delphi Drive
Troy, MI 48098-2815
Dear Mr. Greib:
This responds to your request for an interpretation of Federal Motor Vehicle Safety Standard (FMVSS) No. 302, Flammability of interior materials. You ask whether your companys Passenger Occupant Detection System (PODS) and certain interior electronics and switches must meet this standard if installed on a new vehicle. Based on the information you provided to the agency and the analysis below, our answer is that any material within 13 millimeters (mm) of and incorporated into a component listed in S4.1 of Standard No. 302 would be subject to that standards flammability requirements. Some, but not all, of the components of the PODS system and interior components you ask about would be subject to the standard.
Delphis Passenger Occupant Detection System (PODS)
You explain that the PODS consists of a silicone filled bladder, Electronic Control Unit (ECU), pressure sensor, and a Belt Tension Sensor (BTS). In the picture of the PODS that you provided with your letter, it appears that the bladder is located directly beneath and in contact with the seat cushion. You further state that the ECU and pressure sensor are attached to the bottom (underside) of the seat pan and/or frame. We assume, based on your picture, that the BTS is connected to the seat belt.
You ask several questions about the applicability of FMVSS No. 302 to the PODS, which we will answer in turn.
1) Does NHTSA consider the PODS bladder to be part of the seat cushion?
Our answer is yes, for the purposes of FMVSS No. 302, and that we would likely consider the PODS bladder subject to the standard. S4.2 of FMVSS No. 302 states that any portion of a single or composite material which is within 13 mm of the occupant compartment air space shall meet the flammability requirements. S4.1 further specifies which portions of materials shall meet the flammability requirements by listing a number of components of vehicle occupant compartments, specifically: seat cushions, seat backs, seat belts, headlining, convertible tops, arm rests, all trim panels including door, front, rear, and side panels, compartment shelves, head restraints, floor coverings, sun visors, curtains, shades, wheel housing covers, engine compartment covers, mattress covers, and any other interior materials including padding and crash-deployed elements, that are designed to absorb energy on contact by occupants in the event of a crash. Thus, for example, an intact seat cushion would not be tested for flammability, but rather a section including the surface of the seat cushion exposed to the occupant compartment air space and all the material within 13 mm of that surface.
NHTSA has long interpreted these provisions to mean that a material is subject to FMVSS No. 302s flammability requirements if it is within 13 millimeters of a surface of a component listed in S4.1 and is incorporated into the listed component. Examples of incorporated components include a cable harness permanently attached to a seat cushion or seat back by electronic cables built into the seats internal foam, an air bladder that is attached to a mattress cover, and other materials that are intimately joined with a listed material. It appears from the pictures you sent that the PODS bladder is incorporated into the seat cushion. Therefore, if any portion of the PODS bladder is within 13 mm of a surface of the seat cushion exposed to the occupant compartment air space, and it appears from the pictures you sent that a portion would be, we would consider that portion of the PODS subject to FMVSS No. 302s testing requirements.
2) Are PODS components (ECU and pressure sensor) that are attached to the bottom (underside) of the seat pan and/or frame considered part of the seat cushion?
It does not appear from your pictures that the ECU and pressure sensor are within 13 mm of a surface of a listed component or incorporated into a listed component. Therefore, we would likely not consider the ECU and pressure sensor to be subject to FMVSS No. 302. However, we cannot make a conclusive interpretation without more precise information.
3) Is the area/space underneath the seat considered part of the occupant compartment airspace?
Yes, we would consider this area to be part of the occupant compartment airspace, because it normally contains refreshable air.
4) Are components within that space required to meet FMVSS302?
If they are components listed in S4.1, or if they are within 13 mm of a surface of and incorporated into such components, they would be subject to FMVSS No. 302.
Delphis Interior Electronics and Switch Components
Your letter also described certain Delphi electronics and switches that are exposed to the occupant compartment airspace. You stated that they are not specifically called out in Section 4.1 and are not designed to absorb energy on contact by occupants in the event of a crash. You asked that we confirm that these types of electronics and switches are excluded from the FMVSS302 requirement. As discussed below, some of these electronics and switches would be subject to the standard.
1) Interior display monitors
The picture included with your letter for this question shows the interior of a vehicle from the rear, looking toward the front. Interior display monitors are depicted installed in the front dash, in both head restraints for the front seats, and in the vehicle ceiling (a drop- or fold-down monitor). As discussed above, if the monitor is within 13 millimeters of and incorporated into a listed component, we would consider it subject to FMVSS No. 302s flammability requirements. Head restraints and the front dash are components subject to the standard. Based on your picture, it would therefore appear that display monitors embedded in head restraints and the front dash are subject to the flammability requirements, but drop-down monitors or those installed in the ceiling would not be.
2) Door trim mounted switches
The picture included for this question shows what appears to be the front drivers side door viewed from inside the vehicle, and depicts the door trim with embedded door release handle and various mounted switches. We would consider the switches to be incorporated into the door trim; therefore, if they are within 13 mm of the door trim surface, which they appear to be, we would consider them subject to the flammability requirements.
3) Steering wheel mounted switches
The picture included for this question shows a close-up view of the front surface of a steering wheel, and depicts several switches embedded in the center panel of the steering wheel, close to the outer curved section. Because a steering wheel is designed to include padding elements that absorb energy in the event of a crash, we would consider switches mounted in it to be subject to FMVSS No. 302s flammability requirements.
If you have any further questions, please feel free to contact Rebecca Schade of my staff at (202) 366-2992.
Anthony M. Cooke