Interpretation ID: aiam2152
President
Truck Trailer Manufacturer Association
2430 Pennsylvania Avenue
N.W.
Washington
DC 20037;
Dear Mr. Calvin: This responds to the Truck Trailer Manufacturer Association's Novembe 17, 1975, request that the NHTSA reconsider its opinion that modification of existing tank trailers to increase their volumetric capacity and length does not constitute manufacture of a new air-braked trailer that must comply with Standard No. 121, *Air Brake Systems*. This opinion appears in a letter of August 28, 1975, to Stainless Tank and Equipment, Inc.; The National Traffic and Motor Vehicle Safety Act (the Act) authorize the issuance of motor vehicle safety standards (15 U.S.C. S 1392(a)) and prohibits, among other things, the manufacture of a motor vehicle on or after the date any applicable standard takes effect unless the vehicle conforms to the standard, and is so certified (15 U.S.C. S 1397(a)(1)(A), 1403). With the 1974 Amendments, (15 U.S.C. S 1397(a)(2)(A)) no manufacturer, distributor, dealer, or repair business may perform modifications that render inoperative any device or element of design required by a standard. However, unless the modifications performed are so extensive as to constitute legally the manufacture of a new vehicle, the standards that continue to apply to a vehicle are those in effect at the time of its original manufacture, not those that may have come into effect at a later date.; The modification of a tank trailer to increase its volumetric capacit and length does not, in our view, constitute the manufacture of a new vehicle in the typical situation (about an 18-inch increase in length). For this reason, Standard No. 121 does not apply to existing vehicles that are modified in accordance with your description.; This response does not address the issue of compliance with Federa motor carrier regulations raised in your November 17, 1975, letter.; Sincerely, Frank A. Berndt, Acting Chief Counsel