Interpretation ID: aiam4797
Inc. 1203 Woodbridge Avenue Ann Arbor
MI 48105;
Dear Mr. Kadoya: This responds to your request for interpretations o several safety standards and the Bumper Standard, in connection with a planned 'active' suspension system. I regret the delay in responding to your letter. Your questions are responded to below. By way of background information, the National Highway Traffic Safety Administration (NHTSA) does not provide approvals of motor vehicles or motor vehicle equipment. Under the statutes administered by this agency, it is the responsibility of the manufacturer to ensure that its vehicles and equipment comply with applicable standards. The following represents our opinion based on the facts provided in your letter. According to your letter, Mazda is concerned about the protocol of compliance testing of vehicles equipped with an active suspension system. This concern arises because many standards do not specify a suspension height that is to be used during compliance testing. As you noted, this has not been a concern for conventional suspension systems, since they do not provide for variable height. Mazda's planned active suspension system would be actuated by hydraulic fluid or compressed air, with control pressure being developed by a hydraulic pump or air compressor driven off the engine. Consequently the active suspension system would be operational only when the vehicle's engine is operating. At vehicle speeds in excess of 'z' mph, where z is greater than 35 mph, the suspension height would be lowered by 'x' mm from the nominal or design position for vehicle operation. If the engine/vehicle were not used for several consecutive days, pressure in the control system would fall such that the suspension height may be lowered from the nominal or design position for vehicle operation by 'y' mm, where y is greater than x. The suspension height would return to the nominal or design position for vehicle operation after such an extended period of inoperation almost immediately after starting the vehicle's engine. Before discussing your specific questions, I would like to discuss more generally the issue of how compliance is determined in situations where a standard down not specify a particular test condition. In issuing Federal motor vehicle safety standards, NHTSA attempts to specify all relevant test conditions. The agency does this as part of ensuring that its standards are objective and practicable. As a practical matter, however, it is not possible to specify every conceivable test condition. This is particularly true for ones which may only be relevant to as-yet-undeveloped technologies. In cases where a standard does not specify a particular test condition, we believe there are several relevant factors to consider in interpreting the standard. First, in the absence of specification of a particular test condition, we believe there is a presumption that the requirements need to be met regardless of such test condition, since the standard does not include any language which specifically limits applicability of its requirements to such test condition. For example, where a standard does not specify suspension height, its requirements may need to be met at all heights to which the suspension can be adjusted. Before reaching such a conclusion, however, we also consider the language of the standard as a whole and its purposes. Even if a standard is silent as to a particular test condition, the language of the standard or its purposes may indicate limitations on such test condition. Finally, in situations where a limitation on a particular test condition may appear to be appropriate, we also must consider whether the limitation is sufficiently clear, both with respect to justification and specificity, to be appropriate for interpretation. For example, in a situation where it may appear to be reasonable to limit a particular test condition but it is not obvious what particular limitation should be adopted, it would be inappropriate to select a particular limitation by interpretation. Instead, such a decision should be reached in rulemaking. I will now address the specific questions asked in your letter. Standard No. 108, Lamps, Reflective Devices, and Associated Equipment In asking about Standard No. 108, you stated the following: NHTSA has previously issued an interpretation of the requirements of FMVSS No. 108, at the request of a confidential applicant and dated February 12, 1985, with respect to active suspension equipped vehicles. This interpretation stated that the requirements of FMVSS 108 must be meet (sic), ...at any time in which...' lamps, reflective devices, and associated equipment are to be, '...operated for its intended purpose.' Consequently, headlamps, tailamps, stoplamps, the license plate lamp, and side marker lamps, must comply with the location requirements of FMVSS No. 108 whenever the vehicle's ignition is in the 'on' position. Conversely, reflex reflectors, and turn signal lamps that also function as hazard warning signal flashers must comply with the location requirements when the vehicle's ignition is in either the 'on' or 'off' position. However, it is Mazda's interpretation that hazard warning flashers are not intended to be operational for a period of days, but rather for a period of hours, at maximum, only. You then asked two questions, (1) whether Mazda's understanding of the subject NHTSA interpretation is accurate, and (2) whether Mazda's interpretation of the maximum intended operating duration of hazard warning signal flashers is correct. I note that the February 1985 interpretation was written in the context of a vehicle with a variable height system actuated by hydraulic fluid. In that particular system, the hydraulic pressure relaxed over a period of about three hours after the ignition was turned off, with the result that the vehicle assumed a lower height than it would have during driving. NHTSA stated the following: We believe that the minimum height requirement should be met for any lamp at any time in which it is operated for its intended purpose. Since vehicles at rest do not require use of headlamps, the minimum height requirement would be measured at the point after the ignition is on and when the car begins to travel (your letter implies that the time lag between turning on the ignition and restoration of a complying mounting height is a matter of seconds). On the other hand, the hazard warning signal lamps are frequently operated when the vehicle is stopped, and therefore the minimum mounting height of turn signal lamps, through which they operate, must be met with the ignition off, even if the system requires three hours to deplete itself and lower the vehicle to its minimum height. With respect to your question of whether Mazda's understanding of the interpretation is correct, I would like to note two points. First, while you state that 'the requirements of FMVSS 108' must be met at any time in which lamps, reflective devices, and associated equipment are to be operated for their intended purpose, out interpretation was limited to standard's minimum height requirement. While we are prepared, if asked, to address other requirements, out interpretations should be understood to be limited to their specific facts and conclusions. Second, while our interpretation only addressed headlamps and hazard warning signal lamps, you applied the interpretation for headlamps to tailamps, stoplamps, the license plate lamp, and side marker lamps, and the interpretation for hazard warning signal lamps to reflex reflectors. We concur with this application, with respect to Standard No. 108's minimum height requirement. We do not agree with Mazda's suggested interpretation of the maximum intended operating duration of hazard warning signal flashers. You would apparently like us to conclude that Standard No. 108's minimum height requirement for hazard warning signal flashers does not apply after a vehicle's ignition has been turned off for a matter of days. In addressing how Standard No. 108 applies in the absence of a specification for vehicle height, our February 1985 interpretation differentiates between situations where the vehicle is operating and where it is not. Looking at the purposes of the requirements in question, we believe it is obvious that the minimum height requirement for headlamps is only relevant in situations where the vehicle is operating, while the minimum height for hazard warning signal lamps is also relevant to situations where the vehicle is stopped and the ignition turned off. However, we believe that any determination that Standard No. 108's minimum height requirement for hazard warning signal flashers should not apply after a specified number of hours after the ignition has been turned off is one that would need to be addressed in rulemaking. It is therefore my opinion that the minimum mounting height of hazard warning signal lamps must be met at all heights with the ignition off, even if the system requires days to deplete itself and lower the vehicle to its minimum height. If you believe that a time limitation should be placed on this requirement, I note that you can submit a petition for rulemaking requesting such a change. Standard No. 111, Rearview Mirrors You requested an interpretation of section S5.1.1 of Standard No. 111, which generally requires a passenger car's rearview mirror to 'provide a field of view with an included horizontal angle measured from the projected eye point of at least 20 degrees, and sufficient angle to provide a view of level road surface extending to the horizon beginning at a point not greater than 200 feet to the rear of the vehicle...' You noted that since the specified procedures for determining the location of the driver's eye reference points are made referenced to point with the vehicle's cabin, your active suspension system would not affect these measurements. However, different vehicle heights would be relevant to whether there is a view of level road surface extending to the horizon beginning at a point not greater than 200 feet to the rear of the vehicle. You stated that, based on 'intended purpose,' Mazda's interpretation of Standard No. 111 is that the requirements of this standard are to be met when the vehicle's ignition is in the 'on' position as rearview mirrors are not intended to be used when the vehicle's engine is not operating. You then asked two questions, (1) whether Mazda's interpretation of the requirements of FMVSS No. 111 with respect to the state of the vehicle's switch is correct, and (2) for the purpose of compliance testing to the requirements of FMVSS No. 111, what means of maintaining the intended suspension height for a given speed and operating condition would be satisfactory to NHTSA. We agree that the field of view requirement specified in S5.1.1 for rearview mirrors need not be met for vehicle heights that only occur when the engine is not on, since the requirement is only relevant in situations where the vehicle is operating. However, the requirement would need to be at all vehicle heights that occur during vehicle operation, under the loading conditions specified in S5.1.1. With respect to the issue of how suspension height should be maintained for purposes of compliance testing, you note early in your letter that, for reasons of practicality and safety, a vehicle's engine is not actually operational during compliance testing. However, since the active suspension system derives its power from the vehicle's engine, the system's ability to maintain and regulate suspension height is only possible during engine operation. You therefore indicated that Mazda is seeking guidelines (for several standards) by which Mazda may be able to establish a means to maintain the intended suspension height for compliance testing purposes in the absence of engine operation. We are not able, in an interpretation, to specify a particular means for maintaining suspension height for compliance testing in the absence of engine operation. However, the basic principle that should be followed in selecting a means for maintaining suspension height is that is should not result in different test results than would occur if testing could be conducted with suspension height being maintained by engine operation, i.e., what would happen in the real world. This should be relatively straightforward for section S5.1.1 of Standard No. 111, since the test is static, For a crash test, it is important that a vehicle not be altered in any way that would change the vehicles's crash performance relevant to the aspect of performance being tested. Standard No.204, Steering Control Rearward Displacement In asking about Standard No. 204, you stated the following: Section S4 of this standard specifies the compliance parameter for this standard. Section S5 specifies the testing conditions to determine compliance with this standard. Section S5.1 specifies that the vehicle be loaded to its unloaded vehicle weight. Section S5.5 specifies that the vehicles fuel tank be filled with Stoddard solvent to any capacity between 90 and 95 percent of the total capacity of the tank. Mazda's interpretation of the requirements of this standard is that they are to be met when the vehicle's ignition switch is in the 'on' position only. Furthermore, Mazda interprets the vehicles suspension height pursuant to S5.1 and S5.5 to be the intended suspension height for the vehicle given the conditions of S4, i.e., 30 mph vehicle speed and steered wheels are positioned straight ahead. You then asked whether Mazda's interpretation of the requirements of FMVSS No. 204 are correct. As discussed below, we agree that Standard No. 204's requirements need to be met only at the suspension height that occurs at a 30 mph vehicle speed and with steered wheels positioned straight ahead. Standard No. 204 specifies requirements limiting the rearward displacement of the steering control into the passenger compartment to reduce the likelihood of chest, neck, or head injury. These requirements must be met in a 30 mile per hour perpendicular impact into a fixed collision barrier. While the standard specifies a number of test conditions, it does not specify suspension height. Looking at the Standard No. 204 as a whole, we believe it is clear that NHTSA explicitly decided to limit the standard's evaluation of steering control rearward displacement to how vehicles perform in a 30 mph perpendicular impacts, even though the requirements have relevance at lower and higher speeds. Therefore, we agree that the standard's requirements need to be met only at suspension heights that occur at a 30 mph vehicle speed and with steered wheels positioned straight ahead. With respect to Mazda's question concerning means of maintaining intended suspension height for compliance testing, please see our discussion provided with respect to Standard No. 111. THIS DATABASE WOULD NOT ACCEPT THE COMPLETE LETTER - DUE TO ITS LENGTH. THIS IS PART I. PART II IS ALSO DATED OCTOBER 2, 1990 AND COVERS QUESTIONS ON STANDARDS 208, 301 AND THE BUMPER STANDARD, PART 581. Sincerely, Paul Jackson Rice Chief Counsel;