Interpretation ID: aiam3117
Chief
Car Safety and Regulations Engineer
Rolls-Royce Motors Limited Car Division
Crewe Cheshire CW1 3PL
ENGLAND;
Dear Mr. Knight: This is in response to your letter of August 17, 1979, regarding th requirements in Federal Motor Vehicle Safety Standard (FMVSS) No. 208, Occupant Crash Protection, pertaining to the emergency release warning system for automatic belts.; Paragraph S4.5.3.3(b)(1) of the standard requires an audible an visible warning if the driver's automatic belt system is not in use, as determined by the belt latch mechanism not being fastened. On one of your automatic belt designs the latch mechanism consists of a pivoting bar which slips through a small stitched loop on the end of the belt webbing. You note that this latch mechanism can be fastened without the webbing being connected to the pivot bar, and that in such a case the warning system would not operate even though the belt is not in use. Therefore, you ask if you can install a switch in the automatic belt retractor to detect when insufficient webbing is extended from the retractor to engage with the latch on the door frame. You ask if such a system could be used as an alternative to the existing requirement or, if the standard could be amended to allow the alternative.; In answer to your question, a switch in the retractor of an automati belt system would not satisfy the current warning system requirement if the system did not also include a switch in the emergency release latch mechanism. Further, the Agency does not believe that it is necessary to amend the standard to allow such an alternative. Although it may be true that the existing warning system could be defeated in a belt system such as you describe, the same is true with most warning system requirements. For example, if the standard provided the alternative you suggest, the automatic belt could be 'tied-off' after sufficient webbing was withdrawn from the retractor and the warning system would be defeated. As you know, this method has been used to defeat the warning systems of many manual belts in the past. Therefore, we believe the existing requirement is sufficient to warn vehicle occupants that their automatic belt has been released and should be reconnected.; The 'pivot-bar' release mechanism described in you letter appears t comply with the requirements of the standard. However, we believe that the bar should remain in the released position after the belt webbing has been removed so that the warning system will activate. In other words, we assume that the pivot bar does not re-latch automatically after being released but, rather, requires manual re-latching by the occupant.; Regarding your third question we have enclosed, for your information Notice 14, Docket No. 1- 18, which establishes the new requirements related to controls and displays.; Sincerely, Ralph J. Hitchcock, Chief, Crashworthiness Division, Offic of Vehicle Safety Standards;