Interpretation ID: aiam4371
Chief Co-ordinator
Technical Administration Department
Daihatsu Motor Co.
Ltd.
1.Daihatsu- cho
Ikeda City
Osaka Prefecture
JAPAN;
Dear Ms. Tsujishita: Thank you for your letter requesting an interpretation of th requirements of three of our safety standards. This letter responds to your questions concerning Standard No. 201, *Occupant Protection in Interior Impact*. I have previously responded to your requests for interpretations of the other two standards. I regret the delay in this response.; Your questions concern the requirements of S3.5.1(b) of the standard which provides that 'Along not less than 2 continuous inches of its length, the armrest shall, when measured vertically in side elevation, provide at least 2 inches of coverage within the pelvic impact area.' You expressed concern about determining whether several different armrest designs comply with that requirement. Specifically, you provided three examples and asked how the requirement would apply to each example. Your example I11.1 is an armrest that, when viewed in side elevation (i.e., a view in which a person is looking from in front or behind an armrest to determine how the armrest projects from the door surface) has a flat surface. Example I11.2 is an armrest that has a slightly curved surface. Example I11.3 is an armrest with a surface that is steeply angled inward toward the door. Because of the angling of the armrest, it has a sharp projection at its top.; You believe that examples I11.1 and I11.2 comply with the requiremen of S3.5.1(c). You also believe that example I11.3 would not comply because of its sharp projection. However, you expressed concern about what criteria should be used to distinguish example I11.2 from example I11.3.; S3.5.1(c) of Standard No. 201 does not set any radius of curvatur requirements for armrest surfaces. Thus, a manufacturer is not required to provide an armrest with a flat surface. The only requirement is that the armrest provides at least two inches of coverage within the pelvic impact area. The purpose of the requirement is to reduce potential injuries to an occupant by ensuring that the armrest has a minimum surface area that will spread the force resulting from an occupant impacting the armrest in a crash. Thus, for this requirement to have a meaningful effect, an armrest should be designed to ensure that there is at least two inches of contact between the surface of the armrest and the pelvic impact area of an occupant. If your examples I11.1 and I11.2 provide two inches of coverage within the pelvic impact area, they would appear to comply, since they present an essentially flat surface. Based on your drawing, it appears that the steep inwardly sloping angle of the armrest shown in example I11.3 may not contact a minimum of two inches of the pelvic impact area. One method of determining the degree of occupant contact would be to measure the amount of contact between a test dummy and the armrest in a static push test or in a dynamic side impact test. We share your concern that an armrest not have sharp projections which could concentrate potentially harmful forces on an occupant striking the armrest.; Finally, you provide a drawing of an additional armrest. Briefl described, the armrest has a slightly curved surface with a decreasing radius within the pelvic impact area. At the top of the portion of the armrest within the pelvic impact area there is a small indentation. The agency has previously said, in an interpretation letter of July 1, 1893 to MMC Services, Inc., that bezels and other indentations are not precluded by the standard. However, the area of the indentation will not be measured in determining whether the armrest provides two inches of coverage if the indentation is so deep that it cannot be contacted. Based on your drawing, the indentations shown in your proposed armrest is shallow and would be contactable by an occupant. Thus, the surface area of the indentation would be counted in determining whether the vehicle complied.; Finally, I would point out that S3.5.1(c) is one of three optiona means of compliance that manufacturers may choose. A manufacturer may also meet the requirements of Standard No. 201 by complying with either S3.5.1(a) or S3.5.1(b), in which case it is not necessary to provide two inches of coverage with the pelvic impact area.; If you have any further questions, please let me know. Sincerely, Erika Z. Jones, Chief Counsel