Interpretation ID: aiam1881
Jr.
Montgomery GMC Trucks
Inc.
836 North Glenstone
Springfield
MO 65801;
Dear Mr. Montgomery: This responds to your March 26, 1975, request for guidance i establishing basis for certification to Standard No. 121, *Air brake systems*, in the case of a truck to which you add a third axle.; While your letter lists five bases which might be used i certification, it is not necessary to employ all of these approaches. Rather the National Traffic and Motor Vehicle Safety Act requires that you exercise 'due care' to assure that your products conform to the standard (15 U.S.C. 1397(B)(1)). What constitutes 'due care' in a particular case depends on all relevant facts, including such things as the time to elapse before a new effective date, the availability of test equipment, the limitations of current technology, and above all the diligence evidenced by the manufacturer.; As a general response to your questions, if testing facilities are no available to an intermediate or final-stage manufacturer, or the cost of his testing a vehicle directly to the requirements of Standard No. 121 is prohibitive, such a company should develop an alternative method of determining that his alternations (sic) do not take a vehicle out of compliance with the standard. These methods could include testing of typical installations by independent contractors working with associations of companies such as TBEA or TEBDA, testing of typical installations by suppliers of the axles or other components sought to be installed, engineering calculations by the alterer, the alterer's supplier, or by independent contractors, or copying of installations that have been approved by chassis manufacturers. Component (e.g., axle) suppliers would appear to be a prime source of the type of assistance needed by intermediate and final-stage manufacturers, since they are most familiar with the main components of the installation and have the greatest economic interest in seeing this segment of the industry maintained.; Yours truly, Richard B. Dyson, Assistant Chief Counsel