Interpretation ID: nht75-4.27
DATE: 10/17/75
FROM: AUTHOR UNAVAILABLE; R. B. Dyson; NHTSA
TO: Mercedes-Benz of North America, Inc.
TITLE: FMVSS INTERPRETATION
TEXT: This is in response to your letter dated May 7, 1975, regarding an apparent conflict between the inertia load requirement of Standard 206, Door Locks and Door Retention Components, (49 CFR 571.206, S4.1.1.3) and the test procedure incorporated by S5.1.1.2, Paragraph 5 of SAE Recommended Practice J839b. I regret the delay in responding; your letter was mistakenly routed to our Docket Section and only recently came to our attention.
The answer to your question is that the requirement of S4.1.1.3 controls. It is sufficient that the door latch system withstand a 30g load only in the transverse and longitudinal directions. The system is not required to withstand this load in "any direction."
You asked further about the acceptability of centrifuge testing to demonstrate compliance with the inertia load requirement of Standard 206. Although S5.1.1.2 mentions "approved tests," NHTSA has consistently refused to approve or supervise the methods manufacturers use to test to the standards. Any government inertia load compliance testing will be done in accordance with paragraph 5 of SAE Recommended Practice J839b. Mercedes-Benz, of course, may employ any method it chooses to ensure compliance with this and other safety standards, as long as the product complies. We recognize that centrifuge testing may be highly useful in a variety of applications, and I do not by any means want to discourage innovations in developmental or compliance testing.
Yours Truly,
MERCEDES-BENZ OF NORTH AMERICA. INC.
May 7, 1975
National Highway Traffic Safety Administration
Subject: Request for Clarification; Federal Motor Vehicle Safety Standard No. 206 - Door Locks and Door Retention Components
Paragraph 4.1.1.3 (Inertia Loading) in the above Standard requires that the door lock may not disengage when a longitudinal or transverse load of 30g is applied to the door lock system.
SAE Standard J839b, May 1965, referenced in paragraph 5.1.1.2 requires that compliance with the previous paragraph be demonstrated by approved tests or in accordance with paragraph 5 of the SAE Standard. SAE J839b, paragraph 5.2 requires that the door lock system must withstand a 30g inertia loading in any direction.
Clarification is hereby requested on the directional loading requirements of FMVSS 206. Specifically, shall the loading be applied in any direction as specified in the SAE Standard, or in only the longitudinal and transversal directions as specified in the subject Standard.
We would also appreciate being advised as to the acceptability of loading the lock mechanism in a centrifuge for demonstration of compliance as opposed to dynamic inertial loading of the lock. Dynamic loading on a lock, as it occurs in an accident, would last only approximately one-tenth of a second, whereas centrifugal load testing subjects the test samples to the requirements for approximately one minute.
Should you require additional information concerning this request, do not hesitate in contacting this office.
Heinz W. Gerth Assistant Vice President