Interpretation ID: nht80-2.7

DATE: 04/18/80

FROM: AUTHOR UNAVAILABLE; F. Berndt; NHTSA

TO: Office of Vehicle Safety Compliance

TITLE: FMVSS INTERPRETATION

TEXT:

U.S. DEPARTMENT OF TRANSPORTATION NATIONAL HIGHWAY TRAFFIC SAFETY ADMINISTRATION

April 18, 1980

SUBJECT: Interpretation of Part 581 Damage Criteria

FROM: Chief Counsel

To: Director Office of Vehicle Safety Compliance

You have requested an interpretation of the term "original contour" as it appears in the Part 581 bumper standard, 49 CFR 581.5(c)(8), and 581.5(c)(11)(i) and (ii). The standard limits the amount of deviation from original contour permitted for the vehicle exterior surfaces and bumper face bar 30 minutes after completion of each pendulum and barrier impact. You ask whether original contour refers to the configuration of the exterior surface or face bar prior to the commencement of any testing, or prior to a particular test impact or test mode.

In establishing the Part 581 standard, NHTSA concluded that the typical vehicle will be involved in more than one lowspeed bumper impact over its expected life. In order to assure a performance level which meets the demands of normal driving conditions, the agency determined that bumpers should be capable of providing an acceptable level of damage resistance in a series of impacts. In keeping with this purpose, "original contour", as used in the Part 581 protective criteria, should be established prior to the initiation of any testing, and the tested surface or face bar should not deviate from this contour beyond the prescribed limits throughout the pendulum and barrier test sequences. The other interpretations would not serve the stated purpose, since they are based on a changing reference condition and would permit damage to accumulate from test to test.

Frank Berndt