Interpretation ID: aiam2387
Manager
Gibbes Machinery Co.
Assembly-Blossom-Park & Wheat Streets
P.O. Box 648
Columbia
SC 29202;
Dear Mr. Albergotti: This responds to your August 3, 1976, request for guidance i establishing a basis for certification to Standard No. 121, *Air Brake Systems*, in the case of a truck whose frame and wheelbase is increased by 36 inches. You stated that, in this case, you will not complete the vehicle, but you ask what your responsibilities would be if you completed the vehicle with a used body that was provided by a dealer or a private party.; Because you are modifying an incomplete vehicle by extension of th frame and wheelbase but not completing it, you are considered an incomplete vehicle manufacturer for purposes of certification (49 CFR Part 568, *Vehicles Manufactured in Two or More Stages). Under Part 568, an incomplete vehicle manufacturer is required to pass along the incomplete vehicle document that accompanies the chassis-cab, and to furnish an addendum to it if the validity of the statements in the document has been affected by modifications you made.; Because you would move the rear axles and thereby affect the air brak system, you may need to furnish an addendum to indicate what statements in the document concerning Standard No. 121 should be changed. Assuming, for example, that the General Motors' document states that the vehicle conforms to the standard as long as no changes are made and the center of gravity location is limited, you must determine whether the changes you made have affected the validity of this statement. If the person who completes the vehicle could continue to observe the limitations established by General Motors in the incomplete vehicle document and produce a conforming vehicle, no addendum would be necessary. If, on the other hand, your modifications require new directions to the final stage manufacturer, an addendum must be added.; Although you asked only about compliance with Standard No. 121, i should be noted that a change in the vehicle's wheelbase could also affect compliance with other standards and could require a modification of the Gross Vehicle Weight Rating and Gross Axle Weight Ratings of the vehicle.; If you complete a vehicle for a dealer or an owner, you would b considered the manufacturer of the vehicle and therefore be required to certify its conformity with all applicable standards. This requirement is set forth in S 114 of the National Traffic and Motor Vehicle Safety Act (15 U.S.C. S 1403). The Act requires that manufacturers exercise 'due care' to ensure that their 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 availability of test equipment, the limitations of current technology, and above all the diligence evidenced by the manufacturer.; As a general response to your question, 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 alterations do not take a vehicle out of compliance with the standard. These methods might include testing of typical installations by independent contractors working with associations of companies such as the Truck Body Equipment Association, engineering calculations by yourself or your brake and axle suppliers, or copying of installations that have been approved by chassis manufacturers.; With regard to the use of a used body, the NHTSA considers the mountin of a used body on a new chassis to be the manufacture of a new vehicle. Thus, the completed vehicle must be certified to all applicable standards, including Standard No. 121. In order to do this, you must know the center of gravity of the loaded body in order to determine whether it would, when mounted, exceed the limitations that appear in the incomplete vehicle document on the subject on center-of-gravity height. In the absence of any data, it would seem that a calculation of the center of gravity could be made, provided that due care is exercised.; Thank you for your responsible approach to meeting the requirements o the National Traffic and Motor Vehicle Safety Act. Your letter to the NHTSA is an indication of your diligence in meeting your responsibility to exercise due care.; Sincerely, Frank A. Berndt, Acting Chief Counsel