Interpretation ID: aiam0626
Jr.
Staff Engineer
Society of Automotive Engineers
Inc.
18121 East Eight Mile Road
East Detroit
MI 48021;
Dear Mr. Ziegler: This is in reply to your letter of February 7, 1972, to th Administrator, in which you requested 'clarification' of two requirements of Standard 207 that impose forces on rearward facing seats.; We do not believe that the requirements are unclear. S4.2(b) requires rearward facing seat to withstand a force of 20 times its weight applied in a rearward direction, while S4.3.2.2 requires the restraining device not to release or fail under an acceleration of 20 g's in the direction opposite to that in which the seat folds.; You suggest that these forces and accelerations are equivalent to thos in a 30 mph barrier impact, and point out that none of the existing standards provides for a 30 mph rear impact. The intent of the cited sections is to require rear facing seats to withstand the force of rear end collisions, which occur frequently and are often of considerable severity. We have some doubt that the 20 g acceleration is equivalent to a 30 mph rear barrier impact, frontal 30 mph impacts typically produce accelerations of 30 to 40 g's. Whether it is or not is irrelevant, however, to the validity of the standard. The standard is clear in its own terms, and in our judgment its requirements are appropriate and feasible.; Sincerely, Robert L. Carter, Acting Associate Administrator, Moto Vehicle Programs;