Interpretation ID: 86-3.40

TYPE: INTERPRETATION-NHTSA

DATE: 06/06/86

FROM: AUTHOR UNAVAILABLE; Erika Z. Jones; NHTSA

TO: Robert A. Hutton, Jr. -- Curtis, Bamburg and Crosse

TITLE: FMVSS INTERPRETATION

TEXT:

Robert A. Hutton, Hr., Esq. Curtis, Bamburg & Crossen Attorneys at Law 230 South Bemiston St. Louis, MO 63105

Dear Mr. Hutton:

This responds to your letter asking about inertial-locking seatbelts and seatbacks. We apologize for the delay in our response. You stated that your firm represents a woman who was injured in a 1983 Ford Escort GT. According to your letter, while braking to exit a highway, the driver's seatback was thrown forward, not locking, causing your client to lose control of the car and crash into a guardrail. You asked for information about inertial-lock mechanisms on automobiles, particularly for seat backs and belts in that car, and references to government safety standards. You specifically asked whether there was a standard for the maximum distance the seatback can travel before locking under load.

The National Highway Traffic Safety Administration (NHTSA) issues Federal motor vehicle safety standards, pursuant to the National Traffic and Motor Vehicle Safety Act. The of our standards are revelant to inertial-lock mechanisms.

Federal Motor Vehicle Safety Standard No. 209, Seat Belt Assemblies, specifies requirements for inertial-locking safety belts. Section S4.3(j) specifies the following:

(j) Emergency-locking retractor. An emergency-locking retractor of a Type 1 or Type 2 seat belt assembly, when tested in accordance with the procedures specified in paragraph S5.2(j)--

(1) Shall lock before the webbing extends 1 inch when the retractor is subjected to an acceleration of 0.7 g. . . .

Thus, for safety belts, there is a specific requirement for the maximum distance the webbing may extend before locking under load.

Federal Motor Vehicle Safety Standard No. 207, Seating Systems (49 CFR S571.207), specifies requirements for restraining devices for hinged or folding seats and seat backs. See section S4.3. The standard requires that such seats be equipped with self-locking restraining devices, and specifies both static force and acceleration performance requirements which the restraining devices must meet once engaged. However, the standard does not specify either the load at which an inertial-locking seatback must lock or the maximum distance the seatback can travel before locking under load.

In response to your request for information that relates to the particular car involved in your client's accident, He have enclosed a computer printout listing relevant vehicle owner reports which allege problems similar to that identified by your letter.

I hope this information is helpful. There is no fee for the information.

Sincerely,

Erika Z. Jones Chief Counsel

Enclosure

November 5, 1985

Department of Transportation Motor Vehicle Safety Standards 400 Seventh Street, S.W. Washington, D.C.

Re: Inertial-locking Seatbelts and Seatbacks.

Dear Sir or Madam:

This firm represents a woman who was injured in a 1983 Ford Escort GT. The car is equipped with inertial-locking seatbelts and seatbacks on the front seats. While braking to exit a highway, the driver's seatback was thrown forward -- it did not lock -- causing my client to lose control of the car and crashing into a guardrail.

I an interested i any information you may have concerning inertial-lock mechanisms on automobiles, and particularly seatbacks and belts for that particular car. Any reference to government safety standards, including any standard for the maximum distance the seatback can travel before locking under load would be extremely helpful.

If there is any fee involved in compiling this information, please advise.

Sincerely,

Robert A. Hutton, Jr.

RAH/h