NHTSA Interpretation File Search
Overview
NHTSA's Chief Counsel interprets the statutes that the agency administers and the standards and regulations that it issues. Members of the public may submit requests for interpretation, and the Chief Counsel will respond with a letter of interpretation. These interpretation letters look at the particular facts presented in the question and explain the agency’s opinion on how the law applies given those facts. These letters of interpretation are guidance documents. They do not have the force and effect of law and are not meant to bind the public in any way. They are intended only to provide information to the public regarding existing requirements under the law or agency policies.
Understanding NHTSA’s Online Interpretation Files
NHTSA makes its letters of interpretation available to the public on this webpage.
An interpretation letter represents the opinion of the Chief Counsel based on the facts of individual cases at the time the letter was written. While these letters may be helpful in determining how the agency might answer a question that another person has if that question is similar to a previously considered question, do not assume that a prior interpretation will necessarily apply to your situation.
- Your facts may be sufficiently different from those presented in prior interpretations, such that the agency's answer to you might be different from the answer in the prior interpretation letter;
- Your situation may be completely new to the agency and not addressed in an existing interpretation letter;
- The agency's safety standards or regulations may have changed since the prior interpretation letter was written so that the agency's prior interpretation no longer applies; or
- Some combination of the above, or other, factors.
Searching NHTSA’s Online Interpretation Files
Before beginning a search, it’s important to understand how this online search works. Below we provide some examples of searches you can run. In some cases, the search results may include words similar to what you searched because it utilizes a fuzzy search algorithm.
Single word search
Example: car
Result: Any document containing that word.
Multiple word search
Example: car seat requirements
Result: Any document containing any of these words.
Connector word search
Example: car AND seat AND requirements
Result: Any document containing all of these words.
Note: Search operators such as AND or OR must be in all capital letters.
Phrase in double quotes
Example: "headlamp function"
Result: Any document with that phrase.
Conjunctive search
Example: functionally AND minima
Result: Any document with both of those words.
Wildcard
Example: headl*
Result: Any document with a word beginning with those letters (e.g., headlamp, headlight, headlamps).
Example: no*compl*
Result: Any document beginning with the letters “no” followed by the letters “compl” (e.g., noncompliance, non-complying).
Not
Example: headlamp NOT crash
Result: Any document containing the word “headlamp” and not the word “crash.”
Complex searches
You can combine search operators to write more targeted searches.
Note: The database does not currently support phrase searches with wildcards (e.g., “make* inoperative”).
Example: Headl* AND (supplement* OR auxiliary OR impair*)
Result: Any document containing words that are variants of “headlamp” (headlamp, headlights, etc.) and also containing a variant of “supplement” (supplement, supplemental, etc.) or “impair” (impair, impairment, etc.) or the word “auxiliary.”
Search Tool
NHTSA's Interpretation Files Search
| Interpretations | Date |
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ID: aiam3401OpenMr. John G. Frail, P.O. Box 581, Bronxville, NY 10708; Mr. John G. Frail P.O. Box 581 Bronxville NY 10708; Dear Mr. Frail: This is in reply to your letter of April 9, 1981, to this agenc asking, with respect to Motor Vehicle Safety Standard No. 108, 'whether the minimum edge to edge separation distance between lamp and tail or stop lamp of 4 inches is measured *outside* of the lamp or *inside of the lamp*.' You have asked this question in behalf of an 'OEM supplier' in Germany.; The requirement in Table IV of Standard No. 108 is that the minimu edge to edge separation distance between a turn signal lamp and a tail or stop lamp be 4 inches while the turn signal lamps themselves must have a minimum separation distance of 9 inches between their centerlines. (Your design is somewhat confusing as it depicts centerlines of stop lamps and turn signal lamps at 9 inches.) We interpret this as meaning the minimum separation distance between the edge of lighted area to be 4 inches, as depicted in 'B' in your design. Of course, final responsibility for compliance with this requirement rests on the vehicle manufacturer rather than the equipment manufacturer.; Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam0819OpenMr. Gerard Alexander, President, B. F. Goodrich Tire Company, 500 South Main Street, Akron, OH 44318; Mr. Gerard Alexander President B. F. Goodrich Tire Company 500 South Main Street Akron OH 44318; Dear Mr. Alexander: This is in response to your petition for rulemaking, submitted *Jul 39, 1971*, to amend Motor Vehicle Safety Standard No. 109 (49 CFR S 571.109) and the Tire Identification and Recordkeeping Regulations (49 CFR Part 574). Your petition requests that Standard No. 109 be amended to provide for a special tire category for folding sidewall-reduced tread tires, of which the 'Space Saver Spare' tire you manufacture is an example. You request specifically that requirements for these tires differ from conventional tires as follows: lower minimum breaking-energy values in the strength test (S4.2.2.4, Table II), modified minimum size factors for certain tire size designations which you list, elimination of the condition that the tire be mounted without lubricant for the bead unseating test (S4.2.2.3), and allowing the tire identification number to be placed on the lower sidewall (49 CFR 574.5). *For the reasons stated below, your petition is hereby denied insofar as it requests modifications to the strength and bead unseating requirements of Standard No. 109, and the requirements of Part 574. We make certain recommendations herein regarding your request for modification of the minimum size factors of Standard No. 109*.; The basis for your request for lower breaking-energy values in th strength test is that the values you request represent a level of performance equal to that of a conventional tire having the same amount of tread remaining as a new folding sidewall-reduced tread tire. *The NHTSA cannot accept this argument as a valid basis for specifying lower breaking-energy value requirements for folding sidewall-reduced tread tires. The requirements specified for the strength test are considered to be necessary minimum requirements for all new passenger car tires. Consequently, persons who purchase new tires, regardless of their construction, are entitled to at least this level of performance, and not the level of performance represented by a used tire*.; *The NHTSA does not believe, similarly, that you have presented sufficient basis for elimination of the condition,* in the *bead unseating test procedure, that the tire be mounted for the test without the use of lubricant*. While the NHTSA concurs in the benefits of run-flat performance, which the 'Space Saver Spare' appears to provide, *we do not believe that this advantage outweighs the necessity that the tire conform to the bead unseating requirements when mounted without lubrication. The NHTSA believes the possibility that tires will be mounted without lubrication in the field is sufficiently great to warrant the retention of this condition in the standard's test procedure*.; *We also do not consider sufficient the justification you provide fo your request that the identification number required pursuant to Part 574 be allowed to be placed on the lower sidewall of the tire*. Your statement to the effect that no problems are presented if the number 'wears off' ignores the fact that the number must be retained on the tire for purposes of identification should a defect notification or recall campaign be instituted.; With reference to your request for modification of the minimum siz factor for the tire size designations which you list, *we believe B. F. Goodrich should petition, in accordance* with *guidelines published October 5, 1968 (33 F.R. 14964)*, to *amend the Appendices of Standards Nos. 109 and 110 to provide that folding sidewall-reduced tread tires be added as a separate tire type, including new size designations* and *corresponding values for section width and minimum size factor that you consider appropriate*.; Sincerely, Robert L. Carter, Associate Administrator, Motor Vehicl Programs; |
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ID: aiam5423OpenMr. Karl-Heinz Ziwica General Manager Environmental Engineering BMW of North America, Inc. BMW Plaza Montvale, NJ 07645-1866; Mr. Karl-Heinz Ziwica General Manager Environmental Engineering BMW of North America Inc. BMW Plaza Montvale NJ 07645-1866; "Dear Mr. Ziwica: This responds to your request that the Nationa Highway Traffic Safety Administration (NHTSA) determine that a proposed modification to a previously approved antitheft device on the BMW 7 car line constitutes a de minimis change to the device. The proposed modification is to be effective beginning with the 1995 Model Year (MY). As explained below, the agency concludes that the proposed change to the antitheft device is not a de minimis change. In a Federal Register notice dated October 9, 1986 (51 FR 3633), NHTSA determined that the antitheft device installed as standard equipment on the MY 1988 BMW 7 car line was likely to be as effective as parts marking. In assessing whether changes are de minimis, the agency has focused its inquiry on whether the changed device would continue to provide the same aspects of performance as did the device on which the exemption was based. An example of a de minimis change is the substitution of new components for old components, without changing the aspects of performance provided by the device. NHTSA has also determined that adding a new aspect of performance, making an exempted antitheft device even more effective, while leaving the original aspects undisturbed, is a de minimis change. The change from the original BMW MY 1988 antitheft device to the one proposed for the MY 1995 BMW 7 car line does not present a simple case of either substituting new components for old, without changing the aspects of performance provided, or enhancing the effectiveness of an existing device, by adding a new aspect. Instead, the change is more complex, involving not only the addition of a new aspect (monitoring glass breakage), but also the deletion of some original aspects (monitoring the radio and glove box). The agency is uncertain about the net effect of these changes and is therefore also uncertain whether the new modified device would be at least as effective as the original device. Monitoring glass breakage might decrease the likelihood that a would-be thief would ever enter a vehicle. On the other hand, adding this aspect of performance would not necessarily enhance effectiveness of the antitheft device. If a thief were to gain access to the passenger compartment with a slim-jim or other tool, without breaking the glass, no alarm would sound, making the inside compartment vulnerable to theft. Further, no alarm would sound if the thief then tampered with the radio or glove box, individually. NHTSA believes that the necessity for making judgments about the relative effectiveness of new and removed aspects of performance, and the complexity of the issues underlying those judgments, indicate that the changes are not de minimis. Indeed, these judgments are similar to the ones that the agency must make in considering a new petition for exemption. Accordingly, if BMW wishes the planned MY 1995 device to be the basis for a theft exemption, it must submit a petition with NHTSA pursuant to 49 CFR 543.9(c)(2). Please note that the petition for modification must provide the same information or the modified device as is required under 543.6 for a new device. This includes the statement in 543.6(a)(1) that the antitheft device will be installed as standard equipment on all cars in the line for which an exemption is sought. If you have any questions, please contact Barbara Gray or Rosalind Proctor on (202) 366-1740. Sincerely, Barry Felrice Associate Administrator for Rulemaking"; |
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ID: aiam4090OpenMr. Ron Luce, President, International Transquip Industries, Inc., P.O. Box 590169, Houston, TX 77259; Mr. Ron Luce President International Transquip Industries Inc. P.O. Box 590169 Houston TX 77259; Dear Mr. Luce: This responds to your request for an interpretation of FMVSS No. 121 *Air Brake Systems*. You asked several questions relating to whether vehicles equipped with 'Mini-Max' brakes, a type of brake produced by your company, comply with the standard. Your questions are responded to below. We note that while Question 4 was not asked directly by your letter, the question is implicit with respect to one of the questions you did ask.; By way of background information, the National Highway Traffic Safet Administration (NHTSA) does not give approvals of motor vehicles or equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to ensure that its vehicles or equipment comply with applicable safety standards. The following represents our opinion based on the facts provided in your letter.; *Question 1: Is delayed mechanical parking permissible under sectio S5.6.3 as long as the requirements of S5.6.1 or S5.6.2 are satisfied?*; The second sentence of section S5.6.3 provides that '(o)nce applied the parking brakes shall be held in the applied position solely by mechanical means.' As discussed by a recent notice granting a petition for rulemaking submitted by the California Highway Patrol (copy enclosed), there are at least two issues relating to whether a braking system such as Mini-Max complies with these requirements.; The first issue is whether the system meets the requirements that onc applied, the parking brakes must be held solely be mechanical means. As currently designed, the Mini-Max parking brake can be held by air and not by mechanical means, solely or otherwise, for many hours. Indeed, since a driver will often park the vehicle for a period of time shorter than that required to obtain mechanical holding, there will be many instances when the vehicle is parked and the parking brake never is held by mechanical means. The second issue is whether the parking brakes are held in the applied position. With the current design of the Mini-Max braking system, the air pressure leaks down over time until the mechanical lock is activated. Since the position of the brake components necessarily changes during this time, resulting in reduced parking brake force, there is an issue whether the parking brake is being held in the applied position.; While NHTSA has never concluded that a brake system resulting in fals parking is safe or provided an interpretation that the current Mini-Max system complies with section S5.6.3, we recognize that some past interpretations, as well as one issued by the Bureau of Motor Carrier Safety, could contribute to ambiguity concerning whether some of the features incorporated in the Mini-Max design are permitted by the standard. In light, of that ambiguity and for the other reasons discussed in the grant notice, NHTSA decided to grant the CHP petition to initiate rulemaking on the delayed mechanical park issue rather than issuing an interpretation whether or not such a brake system complies with these requirements.; *Question 2: Is an external pressure separation assembly consisting o a two-way check valve and accompanying steel hex nipple considered to be a component of a brake chamber housing under section S5.6.3 if the assembly is 'permanently bonded' to the housing?*; The answer to this question is no. Section S5.6.3 provides in relevan part that '(t)he parking brake system shall be capable of achieving the minimum performance specified either in S5.6.1 or S5.6.2 with any single leakage-type failure, in any other brake system, of a part designed to contain compressed air or brake fluid (*except failure of a component of a brake chamber housing*).' (Emphasis added.) The dictionary defines 'housing' as 'a fully enclosed case and support for a mechanism.' See *Random House Dictionary of the English Language* (unabridged edition). Thus, the term 'brake chamber housing' refers to the case enclosing a brake chamber. An external pressure separation assembly does not become part of the brake chamber housing merely because it is attached to the housing, whether by 'permanent bonding' or some other means. However, a brake chamber housing could be cast or molded to include a fitting, serving the same purpose as the external pressure assembly, as an integral part of the brake chamber housing.; *Question 3: Is an internal assembly consisting of a diaphragm with th brake chamber housing considered to be a component of the brake chamber housing under section S5.6.3?*; The answer to this question is no. As discussed above, the term 'brak chamber housing' refers to the case enclosing a brake chamber. A diaphragm within the brake chamber is not a component of the case enclosing the brake chamber.; *Question 4: Does section S5.2.1.1 require that capability of releas must be unaffected or that air pressure in the tank must be unaffected?*; Section S5.2.1.1 provides that '(a) *reservoir shall be provided* tha is capable, when pressurized to 90 p.s.i. of releasing the vehicle's parking brakes at least once *and that is unaffected* by a loss of air pressure in the service brake system.' (Emphasis added.) The word 'unaffected' refers back to reservoir.' Thus, the required reservoir is not permitted to be 'affected' by a loss of air pressure in the service brake system, i.e., it must be protected. A reservoir would not meet this requirement if a loss of air pressure in the service brake system resulted in a loss of air pressure in the reservoir, even if the reservoir was still capable of releasing the parking brakes.; *Question 5: If the emergency brakes on trailers can be modulated so a to provide a driver with several applications and releases to move the disabled vehicle off the road after the signal from the low air warning system that the vehicle has lost its service brake system, is it unnecessary for an S5.2.1.1 reservoir to be capable of releasing the brakes?*; The capability of modulation after activation of the low air warnin system does not satisfy the requirements of section S5.2.1.1 (quoted above). That section requires that the reservoir not be affected by loss of service air, i.e., that it be protected, and that, when pressurized to 90 p.s.i. (a pressure that corresponds to the lower end of the range of pressures maintained by compressors), it be capable of releasing the parking brakes at least once. A vehicle's emergency brakes could be capable of modulation after activation of the low air warning system and not meet either of these requirements.; In addition to the notice granting the CHP petition, we are enclosin copies of interpretation letters concerning the Mini-Max system addressed to Navistar, P.T. Brake Lining Company, and the New Jersey Division of Motor Vehicles.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam4209OpenMr. H. Tsujishita, Chief Co-ordinator of Technical Administration Dept., Head Office, Daihatsu Motor Co., Ltd., 1, Daihatsu-Cho, Ikeda City, Osaka Prefecture, JAPAN; Mr. H. Tsujishita Chief Co-ordinator of Technical Administration Dept. Head Office Daihatsu Motor Co. Ltd. 1 Daihatsu-Cho Ikeda City Osaka Prefecture JAPAN; Dear Mr. Tsujishita: This responds to your letter of July 15, 1986, asking thre interpretation questions concerning Federal Motor Vehicle Safety Standards No. 101, *Controls and Displays*, and 108, *Lamps, Reflective Devices, and Associated Equipment*. The answers to your questions are provided below.; By way of background information, the National Highway Traffic Safet Administration does not provide approvals of motor vehicles or motor vehicle equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to ensure that its motor vehicles or equipment comply with applicable standards. The following represents our opinion based on the information provided in your letter.; Your first question concerns the visibility requirements for the uppe beam telltale (indicator). As noted by your letter, section S5.3.3 of Standard No. 101 provides that the light intensity of each telltale shall be such that, when activated, that telltale and its identification are visible to the driver under all daytime and nighttime conditions. The upper beam telltale is one of the telltales subject to that requirement. You note, however, that section S4.5.2 of Standard No. 108 requires a high beam indicator that conforms to SAE Recommended Practice J564a (except that the signal color need not be red). J564a provides that the upper beam indicator should be 'plainly visible to drivers of all heights under normal driving conditions when headlights are required.' Based on this provision, you suggest that the upper beam telltale is not required to be visible to the driver under the daytime conditions when headlamps are not needed. As discussed below, your understanding is incorrect.; The difference between these two requirements is not so great as yo suggest. The reference to 'normal driving conditions' in J564a includes a variety of non-nighttime conditions (e.g., driving at dusk or dawn, and driving in daytime rainstorms) when headlamp use may be required by the States. To the extent that Standard No. 101 requires the telltale to be visible under daylight driving conditions not covered by Standard No. 108, manufacturers must meet the broader requirement. Manufacturers are required to meet all applicable safety standards. We note that while Standards No. 101 and 108 each cover upper beam telltales and specify different requirements, it is possible to meet the requirements of both standards simultaneously.; You stated that under daylight conditions the upper beam cannot dazzl oncoming drivers and that there is therefore no need to inform the driver that the upper beam is on. While there may be less need for this telltale during daylight than at night, Standard No. 101 reflects our believe that there is still a need and requires that the telltale be visible under all daytime and nighttime conditions (if the upper beams are actually on).; Your second question concerns the upper beam telltale minimum are requirement. SAE Recommended Practice J564a, which, as noted above, is referenced by section S4.5.2 of Standard No. 108, provides that the upper beam indicator should consist of a 'light, with a minimum area equivalent to that of a 3/16 in. diameter circle.' You asked how this requirement would apply to two designs.; In the first design, the outline of the telltale symbol would lighte while the area within and around the telltale symbol would not. You suggested that the framed area, i.e., the area within the telltale that is framed by the outline but not lighted itself, can be counted into the minimum area requirement. As discussed below, that is incorrect. In the second design, the telltale symbol would be superimposed on a rectangle. In this case, the entire area within the rectangle would lighten, except for that covered by the symbol itself. You suggested that the lighted area other than that covered by the symbol can be counted toward the minimum area requirement. As discussed below, that is correct.; In referencing SAE Recommended Practice J564a, Standard No. 10 requires that the upper beam indicator must consist of a light, and also specifies the minimum area for that light. It does not specify the shape of the light. If the light is a simple circle which is lighted in its entirety (with the identification required by Standard No. 101 placed adjacent to the circle), that lighted circle must be at least 3/16 inch in diameter. If the light is some other shape, such as the shape of the upper beam symbol or a rectangle in which only part of the area is lighted, the total area which is lighted must be at least as large as the area of a 3/16 inch circle. Thus, in the case of the first design discussed above, only the outline area (i.e., the blue lighted area) of the upper beam symbol can be counted toward the minimum area requirement. The unlighted interior part *i.e., the black area) of the symbol cannot be counted toward the minimum area requirement. In the case of the second design discussed above, the entire (blue) area within the rectangle that lightens can be counted toward the minimum area requirement. However, that part of the rectangle which does not lighten, i.e., the (white) part covered by the symbol, cannot be counted.; Your third question concerns Standard No. 101's illuminatio requirements for a side marker lamp control that is incorporated into the master lighting switch. As suggested by your letter and as discussed below, illumination is not required if the identifying symbol for the side marker lamps is marked on the master lighting switch.; While Table I of Standard No. 101 requires that side marker lam controls be identified with the side marker lamp control symbol and that such identification be illuminated, it also provides that separate identification is not required if controlled by the master lighting switch. Thus, for side marker lamp controls that are incorporated into the master lighting switch, use of the side marker lamp control symbol is voluntary. Since such identification is not required by Standard No. 101, it is our opinion that the standard does not require manufacturers to illuminate such identification if they choose to provide it voluntarily.; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam2652OpenMr. W. G. Milby, Manager, Engineering Services, Blue Bird Body Company, P.O. Box 937, Fort Valley, GA 31030; Mr. W. G. Milby Manager Engineering Services Blue Bird Body Company P.O. Box 937 Fort Valley GA 31030; Dear Mr. Milby: This responds to your June 29, 1977, letter asking whether states ar preempted from regulating minimum seat spacing in school buses by Standard No. 222, *School Bus Passenger Seating and Crash Protection*, which regulates maximum seat spacing.; The National Traffic and Motor Vehicle Safety Act provides in Sectio 103(d):; >>>Whenever a Federal motor vehicle safety standard under thi subchapter is in effect, no State or political subdivision of a State shall have any authority either to establish, or to continue in effect, with respect to any motor vehicle or item of motor vehicle equipment any safety standard applicable to the same aspect of performance of such vehicle or item of equipment which is not identical to the Federal standard. Nothing in this section shall be construed to prevent the Federal Government or the government of any State or political subdivision thereof from establishing a safety requirement applicable to motor vehicles or motor vehicle equipment procured for its own use if such requirement imposes a higher standard of performance than that required to comply with the otherwise applicable Federal standard.<<<; Section 103(d) has the effect of preempting safety standards of th states and their political subdivisions unless they are identical to applicable Federal safety standards that regulate the same aspect of vehicle or equipment performance. The second sentence of the section clarifies that the limitation on safety regulations of general applicability does not prevent governmental entities from specifying additional safety features in vehicles purchased for their own use. The second sentence does not, however, permit these governmental entities to specify safety features that prevent the vehicle or equipment from complying with applicable safety standards.; The state regulations to which you refer in your letter would mandat minimum seat spacing in school buses. Although the requirement of the National Highway Traffic Safety Administration (NHTSA) regulates maximum seat spacing and the state requirements regulate minimum spacing, the regulated aspect of performance is seat spacing. Therefore, it is the NHTSA's opinion that state standards applicable to all school buses concerning minimum seat spacing regulate the same aspect of performance as the Federal standard and would be preempted to the extent that they are not identical with the Federal standard. Section 103(d) would not prevent a state from requiring minimum seat spacing in buses procured for its own use as long as the maximum seat spacing of 20 inches is not violated.; The agency will try to disseminate this opinion to the states a broadly as possible. If you receive further state inquiries on this subject, you should refer them to this office.; Sincerely, Joseph J. Levin, Jr., Chief Counsel |
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ID: aiam4092OpenMr. Carl R. Walker, Manager, Technical Sales and Service, P.T. Brake Lining Company, Inc., P.O. Box 329, Lawrence, MA 01842; Mr. Carl R. Walker Manager Technical Sales and Service P.T. Brake Lining Company Inc. P.O. Box 329 Lawrence MA 01842; Dear Mr. Walker: This responds to your letter addressed to Mr. Richard Radlinski concerning a statement by International Transquip alleging that the National Highway Traffic Safety Administration (NHTSA) and the Bureau of Motor Carrier Safety (BMCS) 'agree' that the Mini-Max brake system produced by that company complies with Federal standards. You noted that International Transquip has referenced a June 6, 1984 letter from BMCS.; NHTSA does not provide approvals of motor vehicles or motor vehicl equipment. Under the National Traffic and Motor Vehicle Safety Act, it is the responsibility of the manufacturer to ensure that its vehicles or equipment complies (sic) with applicable safety standards. I would emphasize that NHTSA has not issued any statement that could be read as 'agreement' that the Mini-Max brake complies with FMVSS No. 121.; We are enclosing a copy of a letter addressed to Navistar whic discusses NHTSA's position concerning the June 6, 1984 letter from BMCS. The letter also notes that the California Highway Patrol (CHP) has raised a number of issues relating to the compliance and overall safety of Mini-Max brakes in connection with a petition for rulemaking, and that International Transquip has submitted comments on CHP's analysis. We have enclosed for your information a notice granting the CHP petition and two related interpretation letters, to International Transquip and the New Jersey Division of Motor Vehicles. The CHP and Mini-Max submissions have been placed in the Petitions for Rulemaking (PRM) Docket for FMVSS No. 121. If you desire copies of those submissions, please contact: Docket Section, National Highway Traffic Safety Administration, Room 5109, 400 Seventh Street, S.W., Washington, DC 20590 (202-426-2768).; Sincerely, Erika Z. Jones, Chief Counsel |
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ID: aiam3890OpenConfidential; Confidential; Dear Mr. Confidential: This is in reply to your letter of August 30, 1984, (not received unti October 17, 1984) with respect to questions of compliance of lighting and bumper requirements on a vehicle equipped with a variable height control system.; Standard No. 108 requires that the center of a headlamp lens be no less than 22 inches from the road surface. You stated that this minimum might not be met with respect to certain headlamp configurations when the ignition is off, and the hydraulic pressure in the height control system relaxes, a period of approximately three hours. You believe that compliance with the mounting height requirement should be judged 'with the ignition switch in only the 'on' position,' the apparent point at which the height control system begins to operate.; We believe that the minimum height requirement should be met for an 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 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.; We also call to your attention paragraph S4.1.3 which forbids th installation of motor vehicle equipment which impairs the effectiveness of lighting equipment required by the standard, and ask that you consider whether a height control system would change vehicle height, pitch, roll, etc., in response to some external or internal condition, in a manner which would affect the performance of headlamps and other lighting equipment.; You have also asked, in essence, which conditions of operation of th system are appropriate for the pendulum and barrier impact tests of the bumper standard, 49 CFR Part 581. Under Sec. 581.5(c), the suspension system is to remain in adjustment and operate in the normal manner, under Sec. 581.6(c) the engine is operating at idling speed. In our opinion, the vehicle is required to meet the pendulum test of Part 581 in any vehicle use scenario in which the system operates, and the barrier test of Part 581 when the engine is idling.; Finally, you requested confidentiality for all information submitte which pertains to the variable height control system. After carefully reviewing the documents, I have determined that your request should be granted. The release of these documents could cause substantial injury to the competitive position of your company. Therefore, I am withholding from the public your letter which contains a detailed description of the variable height control system currently under consideration. I am also deleting all references to the company name. I will instruct all agency personnel having access to this information to accord it confidential treatment.; I hope that this answers your questions. Sincerely, Frank Berndt, Chief Counsel |
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ID: aiam5311OpenMr. Richard A. Zander AlliedSignal Automotive Proving Grounds 32104 State Road 2 New Carlisle, IN 46552; Mr. Richard A. Zander AlliedSignal Automotive Proving Grounds 32104 State Road 2 New Carlisle IN 46552; "Dear Mr. Zander: This responds to your letter asking about the fad and recovery requirements of Federal Motor Vehicle Safety Standard No. 105, Hydraulic Brake Systems. I apologize for the delay in our response. You noted that the standard requires vehicles with a GVWR of 10,000 pounds or less to be capable of making a specified number of fade stops 'at a deceleration not lower than 15 fpsps for each stop.' You stated that you are aware of a number of different understandings within the industry of the quoted phrase, and requested an interpretation as to whether vehicles must be capable of maintaining an average deceleration of at least 15 fpsps or a minimum deceleration of at least 15 fpsps. As discussed below, vehicles must be capable of maintaining a minimum deceleration of at least 15 fpsps. By way of background information, the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1381, et seq.) authorizes the National Highway Safety Administration (NHTSA) to issue safety standards applicable to new motor vehicles and items of motor vehicle equipment. NHTSA does not, however, approve motor vehicles or motor vehicle equipment. Instead, the Safety Act establishes a 'self-certification' process under which each manufacturer is responsible for certifying that its products meet all applicable safety standards. Manufacturers must have some independent basis for their certification that a product complies with all applicable safety standards. This does not necessarily mean that a manufacturer must conduct the specific tests set forth in an applicable standard. Certifications may be based on, among other things, engineering analyses, actual testing, and computer simulations. Whatever the basis for certification, however, the manufacturer must certify that the product complies with a standard as it is written, i.e., that the vehicle will pass all applicable requirements if it is tested exactly according to the standard's test conditions and other specifications. Standard No. 105's fade and recovery test requirements are set forth in S5.1.4. These requirements must be met under the conditions prescribed in S6, when tested according to the procedures set forth in S7. See S5.1. The purpose of the fade and recovery test requirements is to help ensure that brakes retain adequate stopping capacity during and after exposure to conditions cause by prolonged or severe use, such as long, downhill driving. The standard specifies two fade and recovery tests for vehicles with a GVWR of 10,000 pounds or less. Each of the fade and recovery tests consists of three parts: (1) baseline check stops, (2) fade stops, and (3) recovery stops. The requirements for the fade stops are set forth in S5.1.4.2(a), which states that: Each vehicle with a GVWR of 10,000 lbs or less shall be capable of making 5 fade stops (10 fade stops on the second test) from 60 mph at a deceleration not lower than 15 fpsps for each stop, followed by 5 fade stops at the maximum deceleration attainable from 5 to 15 fpsps.' As you noted, S5.1.4.2(a) must be read in conjunction with S7.11.2.1, which sets forth the procedure for conducting the fade stops. It reads, in relevant part, as follows: Make 5 stops from 60 mph at 15 fpsps followed by 5 stops at the maximum attainable deceleration between 5 and 15 fpsps for each stop. ... Attain the required deceleration within 1 second and, as a minimum, maintain it for the remainder of the stopping time. Control force readings may be terminated when the vehicle speed falls to 5 mph. (Emphasis added.) The words 'required deceleration' in S7.11.2.1 refer to 15 fpsps. (That value is set forth both in S5.1.4.2(a) and the first sentence of S7.11.2.1.) Thus, in conducting fade stops, within one second of beginning a stop, a deceleration of 15 fpsps must be attained. S7.11.2.1 then specifies that, 'as a minimum,' the required deceleration (15 fpsps) must be maintained for the remainder of the stopping time. (The word 'it' in the highlighted sentence refers back to the phrase 'required deceleration.') Thus, after a deceleration of 15 fpsps is attained (within one second of beginning the stop), the deceleration cannot drop below 15 fpsps even momentarily. You stated that you are aware of the following three understandings within the industry concerning the meaning of this requirement: 1. The average deceleration for the stop must be greater than 15 fpsps. The average deceleration is calculated from one second after the stop begins to a vehicle speed of 5 mph. 2. After 1 second the deceleration can not drop below 15 fpsps even for an instant. If the deceleration drops below 15 fpsps at any time it is considered a failure even if the average deceleration is greater than 15 fpsps. 3. The average deceleration for the stop must be greater than 15 fpsps and the deceleration must be greater than 15 fpsps for at least 75% of the stop excluding the first second of the stop. Of the three understandings, the first and third are inconsistent with the plain wording of S7.11.2.1 which specifies that, after the required 15 fpsps deceleration is attained (within one second of beginning the stop), it must, as a minimum, be maintained for the remainder of the stopping time. The first and third understandings would, among other things, replace S7.11.2.1's specification that the 15 fpsps deceleration be maintained as a 'minimum' with one that it be maintained as an 'average.' The second understanding is largely correct. It is correct to state that, in conducting a fade stop, after a 15 fpsps deceleration is attained (within one second of beginning the stop), the deceleration cannot drop below 15 fpsps even for an instant. However, if the deceleration did drop below 15 fpsps, that would not necessarily indicate a 'failure' but might simply be an invalid test. As you note in your letter, a deceleration might fall below 15 fpsps because the driver did not compensate for in-stop fade. However, if a vehicle was unable to pass Standard No. 105's fade stop test requirements at the specified deceleration rates, it would not comply with the standard, notwithstanding the fact that it might be able to pass the requirements at slightly lower deceleration rates. You stated in your letter that the second understanding appears to not consider the intent of the fade procedure, the intent being that a vehicle must be capable of making multiple high deceleration stops in a short period of time without drastic changes in effectiveness. As discussed above, the purpose of the fade and recovery test requirements is to help ensure that brakes retain adequate stopping capacity during and after exposure to conditions cause by prolonged or severe use, such as long, downhill driving. If a vehicle was unable to pass Standard No. 105's fade stop test requirements at the specified deceleration rates, it would indicate inadequate stopping capability during conditions caused by prolonged or severe use, such as long, downhill driving. You also stated that in the Laboratory Test Procedure for Standard No. 105, published by NHTSA's Office of Vehicle Safety Compliance (OVSC), the data sheet for the fade stops requests the following information for the deceleration: 'Average Sust Decel.' You stated that it therefore appears that NHTSA's interpretation of the phrase 'at a deceleration not lower than 15 fpsps for each stop' is 'the average sustained deceleration.' It is incorrect to interpret the OVSC Laboratory Test Procedures as limiting the requirements of the Federal motor vehicle safety standards. I call your attention to the following note which is set forth at the beginning of the Laboratory Test Procedure: The OVSC Laboratory Test Procedures, prepared for use by independent laboratories under contract to conduct compliance tests for the OVSC, are not intended to limit the requirements of the applicable FMVSS(s). In some cases, the OVSC Laboratory Test Procedures do not include all of the various FMVSS minimum performance requirements. Sometimes, recognizing applicable test tolerances, the Test Procedures specify test conditions which are less severe than the minimum requirements of the standards themselves. Therefore, compliance of a vehicle or item of motor vehicle equipment is not necessarily guaranteed if the manufacturer limits certification tests to those described in the OVSC Laboratory Test Procedures. I am enclosing a copy of the most recent version of the Laboratory Test Procedure for Standard No. 105, in response to your request. I hope this information is helpful. If you have any further questions, please feel free to contact David Elias of my staff at this address or by telephone at (202) 366- 2992. Sincerely, John Womack Acting Chief Counsel Enclosure"; |
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ID: aiam4797OpenMr. S. Kadoya Manager Safety and Technology Mazda Research and Development of North America, Inc. 1203 Woodbridge Avenue Ann Arbor, MI 48105; Mr. S. Kadoya Manager Safety and Technology Mazda Research and Development of North America 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; |
Request an Interpretation
You may email your request to Interpretations.NHTSA@dot.gov or send your request in hard copy to:
The Chief Counsel
National Highway Traffic Safety Administration, W41-326
U.S. Department of Transportation
1200 New Jersey Avenue SE
Washington, DC 20590
If you want to talk to someone at NHTSA about what a request for interpretation should include, call the Office of the Chief Counsel at 202-366-2992.
Please note that NHTSA’s response will be made available in this online database, and that the incoming interpretation request may also be made publicly available.