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: 1985-02.50OpenTYPE: INTERPRETATION-NHTSA DATE: 06/27/85 FROM: AUTHOR UNAVAILABLE; Jeffrey R. Miller; NHTSA TO: Mr. M. Ojima TITLE: FMVSS INTERPRETATION TEXT:
June 27, 1985 Mr. M. Ojima Manager Asahi Glass Company, Ltd. 1-2, Marunouchi 2-Chrome. Chiyoda-Ku, Tokyo, Japan Dear Mr. Ojima: Thank you for your letter of May 8, 1985, to Administrator Steed concerning the requirements of Standard No. 205, Glazing Materials, that apply to glass-plastic glazing. The answers to your questions are discussed below. Your first question concerns the requirements of the boil and humidity tests that apply to glass plastic glazing. You explained that after the boil test and the humidity test, your plastic material develops a haze. You stated that the maximum haze resulting from the boil test is approximately 10 percent. However, after the sample had been left at room temperature for 24 hours, the plastic haze disappeared and the plastic "completely recovered to the original condition." As you correctly noted, Standard No. 205 requires glass-plastic glazing to pass Test No. 3, Humidity, and Test 4, Boil Test, of the American National Standard Institute's "Safety Code for Safety Glazing Materials for Glazing Motor Vehicles Operating on Land Highways" Z26.1-1977, January 26, 1977 as supplemented by Z26.1a, July 3, 1980, which is incorporated by reference in our standard. As explained in the preamble to the November 16, 1983, final rule setting performance requirements for glass-plastic glazing, the purpose of the humidity and boil tests is to ensure that the plastic layer of glass-plastic glazing does not delaminate when exposed to high temperatures and humidity. Since the temporary haze does not result in a permanent change in the structure of the glazing, which would occur if the glazing delaminated, we do not consider the temporary haze to be a failure of the boil or humidity tests. The glazing must, of course, comply with Test No. 17, Abrasion Resistance, as modified by Standard No. 205, which is directly meant to limit haze. Your second question concerned whether you should mark glass-plastic as "AS1" or AS14". You noted that ANSI Z26.1-1983 specifies that glass-plastic glazing should be marked "AS1", while our standard specifies the use of "AS14". Standard No. 205 incorporates by reference the 1977 version of Z26.1a, July 3, 1980, and does not incorporate Z26.1-1983. Therefore, in accordance with S6.1 of Standard No. 205, you must mark glass-plastic glazing manufactured for sale in the United States with "AS14". If you have any further questions, please let me know. Sincerely, Original Signed By Jeffrey R. Miller Chief Counsel |
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ID: nht74-1.29OpenDATE: 08/13/74 FROM: AUTHOR UNAVAILABLE; Robert L. Carter; NHTSA TO: Mr. Eric L. Clabourgh COPYEE: L. OWEN TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your recent letter to the Administrator, National Highway Traffic Safety Administration, concerning the placement of front turn signal lamps on fire trucks. Federal Motor Vehicle Safety Standard No. 108, "Lamps, Reflective Devices, and Associated Equipment" (copy enclosed) requires that front turn signal lamps be located "at or near the front and be spaced "as far apart as practicable." We would, therefore, have no objection to moving the front turn signal lamps on the fire truck from the side to the front. Locating the lamps on the front could also reduce the chance of damage to them, which might occur if they were located on the side. Sincerely, ATTACH. Administrator And Counsel N.H.T.S.A. Washington, D.C. Gentlemen: I am in need of urgent information deciding a standard, specifically, standard 108, I understand, applies to big trucks. All effective 1-1-68. Soon we, the city of (Illegible Word) town commissioners, will receive a fire truck chassis made by international and the rest by the American fire apparatus co. of (Illegible Word), Iowa. In a few months it will be delivered and it was bought with (Illegible Words) sharing money. We are in debate! the Fire (Illegible Text) (Graphics omitted) These International beauties won't make the taxpayers see red. Fires and fire departments come in a lot of different sizes -- and so do international Fire Truck chassis. There's one to fit your budget, sure, but more important they'll also fit the kind of community you serve and the kinds of fires you fight. I like the CARGOSTAR(R) top right, a short wheel base lets you turn in tight spots. The cab-over design gives you better visibility, and the cab also tilts forward for quicker, handier engine access. You can get it equipped the way you want it, with power to pump up to 1,250 gallons a minute. On the left is a customized FLEETSTAR* chassis it comes with GVW ratings from 23,000 to 54,000 pounds and pound for pound it's the most efficient, economical fire-fighter around. Down front is international's LOADSTAR* it can be customized as an assist-type vehicle, rescue truck pumper, or ladder truck. And this one has an engine and fuel capacity big enough to keep on working till the smoke clears. (Graphics omitted) |
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ID: nht93-9.18OpenDATE: December 16, 1993 FROM: Erika Z. Jones -- Mayer, Brown & Platt TO: John Womack -- Acting Chief Counsel, NHTSA TITLE: None ATTACHMT: Attached To Letter Dated 6/9/94 From John Womack To Erika Jones (A42; Std. 213; VSA 103(d) TEXT: Dear Mr. Womack: I am writing to obtain your opinion about the applicability to automotive child restraints of a California statute regarding flammability resistance of upholstered furniture, California Business and Professions Code, Division 8, Chapter 3, @ 19006 and 19161. The California law has been implemented in state regulations, Cal. Code Regs., title 4, @ 1370 et seq. The implementing regulations incorporate Technical Bulletin 117 of the State of California Bureau of Home Furnishings; which specifies the required performance requirements and test procedures. I have enclosed a "Flammability Information Package" prepared by the State of California which includes a copy of the statute, regulations and Technical Bulletin cited above. Automobile child restraints are subject to Federal Motor Vehicle Safety Standard 213 (49 C.F.R. @ 571.213), which incorporates FMVSS 302, pertaining to the flammability of interior materials contained in motor vehicles and motor vehicle equipment. FMVSS 213 and FMVSS 302 specifically regulate the flammability resistance of these interior materials and, thus, pertain to the same aspect of performance as that addressed by the California law. The National Traffic and Motor Vehicle Safety Act preempts any state statute or regulation that is not identical to the federal standard. (15 U.S.C. 1392(d). n1/ As the California 2 flammability standard is not identical to the federal flammability requirements as contained in FMVSS 213 and FMVSS 302, it appears that the California standard is preempted by the NHTSA standards, insofar as the California law would be applied to automotive child restraints. Therefore, it appears that the California flammability requirements are not applicable to automotive child restraints certified to comply with FMVSS 213, and such restraints need not comply with the requirements of that statute. n1/ The statute reads: "Whenever a Federal motor vehicle safety standard established under this title 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." Please confirm whether NHTSA concurs in our understanding of the applicability of the California flammability standard to automotive child restraints. Sincerely, enclosure |
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ID: nht76-2.44OpenDATE: 02/26/76 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: H. A. Heffron, Esq. TITLE: FMVSS INTERPRETATION TEXT: This is in reply to your letter of February 13, 1976, asking for a confirmation of your understanding that Motor Vehicle Safety Standard No. 108 does not apply to lighting equipment intended as replacement equipment on motor vehicles manufactured before January 1, 1972. You are correct in your interpretation. The effective date of Standard No. 108 in its current form is January 1, 1972. Therefore, the term "any vehicle to which this standard applies" contained in S4.7.1 means a motor vehicle manufactured on or after January 1, 1972, and school bus signal lamps intended as replacements for similar lamps on pre-1972 buses are not required to conform to Standard No. 108. This also means, of course, that the manufacturer has no obligation to certify conformance to all applicable Federal motor vehicle safety standards. As motor vehicle equipment, however, its manufacturer would be subject to the notification and remedy provisions of the National Traffic and Motor Vehicle Safety Act in the event of the determination of a safety related defect. Yours truly, ATTACH. February 13, 1976 Office of the Chief Counsel -- National Highway Traffic Safety Administration Dear Sir: This inquiry concerns the applicability of MVSS 108 to school bus replacement lighting equipment. MVSS 108 provides with respect to replacement equipment as follows: (S4.7.1) "Each lamp, reflective device, or item of associated equipment manufactured to replace any lamp, reflective device, or item of associated equipment on any vehicle to which this standard applies, shall be designed to conform with this standard." I note that as originally issued the amendment to MVSS 108 which extended its applicability to requirements for replacement lighting equipment was to be effective on July 1, 1971 (35 Fed. Reg. 16840) and this effective date was subsequently changed to January 1, 1972. (36 Fed. Reg. 1896) My specific question is with respect to school buses manufactured prior to January 1, 1972. As I read MVSS 108, its requirements do not apply to replacement equipment for these older vehicles manufactured prior to January 1972 and, therefore, replacement lighting equipment for such pre-1972 school buses, including replacements for the signal lamp required of school buses in S4.1.4, are not required to conform to MVSS 108. Would you please advise whether any understanding of the applicability of MVSS 108 is correct. Very truly yours, Howard A. Heffron |
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ID: nht93-4.7OpenDATE: May 21, 1993 FROM: John Womack -- Acting Chief Counsel, U.S. Department of Transportation, NHTSA TO: Joseph G. Wilson -- President, The Monmouth Corporation TITLE: None ATTACHMT: Attached to letter dated 01-01-93 EST from Joseph G. Wilson to John Womack (OCC 8594) TEXT: Thank you for your letter informing us of the Blu-Lite System, which your company developed. You stated that the system "protects a vehicle driver from the threat of rear-end collision." You enclosed a brochure for our information, and would like to demonstrate your system to us. We regret that we cannot accept your offer for a demonstration. In addition, as discussed below, we must advise you that Blu-Lite appears to conflict with both Federal and local laws. Your brochure shows that Blu-Lite is a three compartment lamp, consisting of a center compartment with blue lens (described as "emergency stop") flanked by two "red stop lights". Blue-Lite is shown installed in the rear parcel shelf, apparently as a substitute for the center highmounted stop lamp. In use, Blu-Lite flashes rapidly. The center highmounted stop lamp has been required as original equipment on all passenger cars manufactured on and after September 1, 1985. The effect of Section 108(a)(2)(A) of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. 1397(a)(2)(A)) is to forbid any manufacturer, distributor, dealer, or motor vehicle repair business from removing the center highmounted stop lamp, and replacing it with any lamp that does not meet the requirements for the center lamp that was original equipment. Blu-Lite does not meet the original equipment specifications in lamp color, which must be red, and in operation, which must be steady-burning. Thus, any manufacturer, distributor, dealer, or motor vehicle repair business who substituted Blu-Lite for an original equipment center highmounted stop lamp would appear to be in violation of Section 108(a)(2)(A). The Safety Act does not prohibit a vehicle owner from installing Blu-Lite, or any other person, including manufacturers, distributors, dealers, and motor vehicle repair businesses, from installing it on a passenger car manufactured before September 1, 1985. However, the legality of its use must be determined under state laws. It is our impression that many states allow the use of blue lamps only on emergency vehicles. Additionally, many states have laws similar to the Federal one as it relates to the performance and use of the center highmounted stop lamp. If you wish to confirm this, we suggest that you consult the American Association of Motor Vehicle Administrators, 4600 Wilson Boulevard, Arlington, Va. 22203. |
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ID: nht91-6.37OpenDATE: October 23, 1991 FROM: Paul Jackson Rice -- Chief Counsel, NHTSA TO: None TITLE: None ATTACHMT: Attached to letter dated 9-6-91 to Taylor Vinson TEXT: This responds to your letter of September 6, 1991, to Mr. Vinson, asking whether a vehicle you are developing would be classified as a multipurpose passenger vehicle for the purposes of the Federal motor vehicle safety standards. I am pleased to be able to explain our law and regulations for you. At the outset, I would like to make clear that the National Traffic Motor Vehicle Safety Act (15 U.S.C. 1381 et seq.) places the responsibility for classifying a particular vehicle in the first instance on the vehicle's manufacturer. For this reason, NHTSA does not approve or endorse any vehicle classification before the manufacturer itself has classified a particular vehicle. NHTSA may reexamine the manufacturer's classification during the course of any enforcement actions. We will, however, tentatively state how we believe we would classify this vehicle for the purposes of our safety standards. It is important that you understand that these tentative statements of classification are based entirely on our understanding of the information presented in your letter to us. These tentative statements about the vehicle's classification may change after NHTSA has had an opportunity to examine the vehicle itself or otherwise acquire additional information about the vehicle. With those caveats, we believe that the vehicle referenced in your letter could be classified as a multipurpose passenger vehicle for the purposes of our safety standards. The term "multipurpose passenger vehicle" is defined in 49 CFR S571.3 as "a motor vehicle with motive power, except a trailer, designed to carry 10 persons or less which is constructed either on a truck chassis or with special features for occasional off-road operation." In your letter, you state that the vehicle's chassis should be considered a truck chassis because it "was originally designed to provide cargo-carrying capability as well as to permit rough road and off the road vehicle operation." Additionally, you state that the approach and departure angles and the running clearance dimensions for this vehicle are more similar to other vehicles which have been classified by their manufacturers as multipurpose passenger vehicles than vehicles that have been classified as passenger cars. Based upon this description, it appears to us that this vehicle could be classified as a multipurpose passenger vehicle. I hope you find this information helpful. The version of your letter that has been placed in the public docket has all the information for which you requested confidential treatment deleted from it. If you have further questions, please contact Mary Versailles of my staff at this address or by telephone at (202) 366-2992. |
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ID: nht90-2.57OpenTYPE: INTERPRETATION-NHTSA DATE: 05/30/90 FROM: STEPHEN P. WOOD -- ACTING CHIEF COUNSEL NHTSA TO: MICHAEL S. KMIECIK TITLE: NONE ATTACHMT: LETTER FROM MICHAEL S. KMIECIK TO NHTSA, DATED 11/21/89 TEXT: This responds to your letter with respect to vehicle modification kits you wish to purchase and use in the conversion of used Datsun cars. You asked about the Part 581 Bumper Standard and Safety Standard No. 215 with respect to using Datsuns produced be fore September 1, 1978. You asked whether the kit would meet the requirements of Safety Standard No. 215. I regret the delay in responding. (I note that you sent a separate letter asking about the safety standards that apply to 1974-78 convertibles, an d whether the conversion kit meets those standards. I am responding to that letter separately). We appreciate your efforts to meet the requirements of the National Traffic and Motor Vehicle Safety Act. A provision of the Act requires, in essence, that vehicle alterations by a motor vehicle manufacturer, distributor, dealer or repair business must not render wholly or partially inoperative any device or element of design installed on that vehicle in accordance with a Federal motor vehicle safety standard. This means that a vehicle at the end of its conversion process must continue to meet the sta ndards that applied at the time that it was first manufactured. As you may know, the Part 581 Bumper Standard became applicable to passenger cars manufactured on or after September 1, 1978. It replaced Safety Standard No. 215, Exterior Protection, which applied to passenger cars manufactured from September 1, 1972 t o August 30, 1978. In converting a car to which Standard No. 215 originally applied, care must be taken to ensure that the changes do not affect the ability to conform to the applicable performance requirements of that standard (copy enclosed). We regret that we are unabl e to advise you of the effect that any specific modifications would have on the performance of the vehicle as converted. The manufacturer of the kit may be able to provide information on this subject. 2 You also requested a copy of Safety Standard No. 108, Lamps, Reflective Devices, and Associated Equipment. I have enclosed a copy of that standard revised as of October 1, 1989. I have also enclosed an information sheet which provides information for n ew manufacturers, and includes information concerning how to obtain copies of safety standards. I hope this information is helpful. ENCLOSURES |
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ID: 11643MLSOpen Mr. J. Brian Powers Dear Mr. Powers: This responds to your letter asking whether Compressed Natural Gas (CNG) containers used as fuel tanks for motor vehicles in the United States require periodic hydrostatic testing. You stated that these containers had been purchased by BC gas and stored in a warehouse, but did not state the date of their manufacture. The answer is no. This agency, the National Highway Traffic Safety Administration (NHTSA), has no authority to require the periodic testing of motor vehicles or items of motor vehicle equipment, after the first consumer purchase. Congress has authorized NHTSA to issue Federal motor vehicle safety standards (FMVSSs) for new motor vehicles and new items of motor vehicle equipment. The agency has exercised this authority to issue FMVSS No. 304, Compressed natural gas fuel container integrity, (49 CFR 571.304) which specifies requirements for the integrity of new CNG containers used to fuel motor vehicles. One such requirement is that each new CNG container comply with a hydrostatic burst test. Each new CNG container manufactured on or after March 27, 1995 (the date the standard took effect) must comply with the hydrostatic burst test and the other requirements in FMVSS No. 304 and be certified as complying with that standard when it is sold. However, after the first consumer purchase of a motor vehicle or an item of motor vehicle equipment, NHTSA's authority is much more limited and does not extend to periodic hydrostatic testing (or any other periodic testing) of motor vehicles or such equipment. I wish to note that another agency of the U.S. Department of Transportation, the Research and Special Programs Administration (RSPA), is authorized by Congress to issue standards for containers used to transport hazardous materials, including CNG containers. RSPA, however, does not have the statutory authority to regulate CNG containers that are used to fuel a motor vehicle. In other words, there are no Federal requirements applicable to the periodic retesting of CNG containers designed to fuel a motor vehicle. Even though there are no Federal requirements about the periodic hydrostatic testing of CNG containers used to fuel motor vehicles, each state has the authority to regulate motor vehicles while they are in use. Accordingly, a state could regulate the testing of CNG containers in the aftermarket. I hope you find this information helpful. If you have any other questions, please contact Marvin Shaw at this address or by phone at (202) 366-2992. Sincerely, Samuel J. Dubbin Chief Counsel ref: 304 d:4/19/96
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1996 |
ID: 2508yOpen Mr. Michael S. Kmiecik Dear Mr. Kmiecik: This responds to your letter with respect to vehicle modification kits you wish to purchase and use in the conversion of used Datsun cars. You asked about the Part 58l Bumper Standard and Safety Standard No. 2l5 with respect to using Datsuns produced before September l, l978. You asked whether the kit would meet the requirements of Safety Standard No. 2l5. I regret the delay in responding. (I note that you sent a separate letter asking about the safety standards that apply to l974-78 convertibles, and whether the conversion kit meets those standards. I am responding to that letter separately). We appreciate your efforts to meet the requirements of the National Traffic and Motor Vehicle Safety Act. A provision of the Act requires, in essence, that vehicle alterations by a motor vehicle manufacturer, distributor, dealer or repair business must not render wholly or partially inoperative any device or element of design installed on that vehicle in accordance with a Federal motor vehicle safety standard. This means that a vehicle at the end of its conversion process must continue to meet the standards that applied at the time that it was first manufactured. As you may know, the Part 58l Bumper Standard became applicable to passenger cars manufactured on or after September l, l978. It replaced Safety Standard No. 2l5, Exterior Protection, which applied to passenger cars manufactured from September l, l972 to August 30, l978. In converting a car to which Standard No. 2l5 originally applied, care must be taken to ensure that the changes do not affect the ability to conform to the applicable performance requirements of that standard (copy enclosed). We regret that we are unable to advise you of the effect that any specific modifications would have on the performance of the vehicle as converted. The manufacturer of the kit may be able to provide information on this subject. You also requested a copy of Safety Standard No. l08, Lamps, Reflective Devices, and Associated Equipment. I have enclosed a copy of that standard revised as of October l, l989. I have also enclosed an information sheet which provides information for new manufacturers, and includes information concerning how to obtain copies of safety standards. I hope this information is helpful. Sincerely, Stephen P. Wood Acting Chief Counsel Enclosures ref:58l:VSA |
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ID: nht74-4.22OpenDATE: 08/05/74 FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA TO: Oshkosh Truck Corporation TITLE: FMVSS INTERPRETATION TEXT: This responds to your July 2, 1974, question whether a truck complies with the dynamometer requirements of S5.4 of Standard No. 121, Air brake systems, if its brakes are actuated by smaller slack adjusters and brake chambers than those specified by the brake manufacturer to establish torque levels which comply with the standard. Your question arises under the interim requirements of S5.3.1.2 and the full requirements of S5.4.2 and S5.4.3 as they apply to the on/off-highway category. Standard No. 121 is a vehicle requirement, and the NHTSA will conduct compliance testing for dynamometer requirements using the force levels applied to the brakes on the particular vehicle it is testing. This means that if you use 5.5-inch slack adjusters and 30-inch brake chambers on your truck, the NHTSA would use the force applied by these components in its compliance testing. There is no prohibition to your modifying the brake manufacturer's "recommended package" to suit your needs. However, you should be able to show that, in the exercise of due care, the brake assembly meets the requirements of S5.4 as modified. If you believe that the established dynamometer requirements conflict with optimum handling and stopping performance, you may, under NHTSA procedural rules (49 CFR 563, copy enclosed) petition to modify the standard. In response to your July 10, 1974, letter asking whether an air-over-hydraulic front brake is subject to certain requirements of Standard No. 105a, I enclose a preamble to that standard which states that air-over-hydraulic systems are regulated only by standard No. 121. |
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.