Dietmar K. Haenchen, Process Leader
Safety Affairs and Vehicle Testing
Volkswagen of America, Inc.
Mail Code 2A02
3800 Hamlin Road
Auburn Hills, MI 48326
Dear Mr. Haenchen:
This responds to your letter to the National Highway Traffic Safety Administration (NHTSA), concerning Federal Motor Vehicle Safety Standard No. 201, Occupant Protection in Interior Impact. You are particularly concerned about the applicability of the upper interior head impact requirements of Standard No. 201 as they apply to sunroof systems and vehicles using roof panels made of glazing materials.
One of your concerns relates to sunroofs or fixed glass roof panels and trim panel covers that may cover these components. Your letter notes that S8.2 of Standard No. 201 directs that movable sunroofs must be placed in the fully open position for testing. Volkswagen also states that it believes it is reasonable to conclude that a single sliding trim cover for a movable sunroof should also be in the open position for testing under S8.2. In your view, if a movable sunroof is in the open position, the cover would be open as well. You then address the instance where a sunroof might be covered by multiple trim panels that may either be in a closed or open position when the sunroof is in use. In such an instance Volkswagen believes that the correct interpretation of Standard No. 201 is that the definition of sunroof would include any accompanying roof panel that can be opened.
NHTSA agrees with your interpretation. S8.2(c) of Standard No. 201 specifies that movable sunroofs are placed in the fully open position for vehicle testing. Provided that the trim or cover involved does not extend beyond the perimeter of the sunroof opening, we believe it is reasonable to include such covers or trim as being part of the sunroof for the purposes of Standard No. 201. We note that this interpretation is consistent with a previous interpretation contained in a February 19, 1999 letter to Mr. George L. Parker of the Association of International Automobile Manufacturers. In that letter, we stated that sunroofs should be open during both testing and the target location procedure. This position was based on our view that vehicles were likely to be operated with the sunroof in the open position. We further stated that sunroofs should be open during the target location procedure. As the trim or covers over the sunroof opening would impede in locating targets and testing if they remained in the closed position, we agree with your suggested interpretation.
Your letter also asks about roofs with fixed glass panels. You note that prior NHTSA interpretations state that impacts where the Head Injury Criterion (HIC) is affected by contact with glazing are invalid. In the case of a roof incorporating a fixed glass panel with a moveable shade or sun cover, you ask if testing should be conducted with the shade in an opened or closed position. Your letter further states that Volkswagen believes that the correct interpretation would be that the shade be open for testing and that impacts should be invalid when contact with a fixed glass roof panel are such that the HIC is affected. If NHTSA determines that such a shade or sun cover should remain in the closed position, you propose an alternate interpretation. Under this alternate interpretation, Volkswagen contends that impacts where the headform deforms the cover to the point where the cover contacts the glass panel should also be invalid.
You are correct in stating that prior NHTSA interpretations have indicated that impacts will be determined to be invalid when the anterior portion of the Full Motion Headform (FMH) strikes fixed glazing near or at the same time that the forehead impact zone strikes a nearby target. Standard No. 201 is not intended to prevent injuries resulting from impacts with glazing. If such an impact occurs, thereby affecting the HIC, the test is invalid.
We also agree that any shade or cover for a fixed glass roof panel be in the open position for testing (as well as target location). A sliding shade or cover for such a fixed glass panel is likely to be located in close proximity to the glass panel itself. Thus it could be impracticable to incorporate safety features into such a shade that would allow compliance with Standard No. 201.
I hope this information is helpful. If you have any further questions, please feel free to call Otto Matheke of my staff at (202) 366-2992.