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Interpretation ID: 11345WKM

Mr. Lance Tunick
Manager, Special Projects
Vehicle Science Corporation
Post Office Box 1015
Golden, CO 80402-1015

Dear Mr. Tunick:

This responds to your letter asking whether your rear side door locking system would meet the requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 206, Door locks and door retention components (49 CFR 571.206). The answer is a qualified yes.

By way of background, the National Highway Traffic Safety Administration (NHTSA) has the authority to issue Federal motor vehicle safety standards (FMVSS) applicable to new motor vehicles and new items of motor vehicle equipment. NHTSA, however, does not approve motor vehicles or motor vehicle equipment, nor do we endorse any commercial products. The following represents our opinion based on the facts set forth in your letter.

You stated that on your locking system, the first pull of the inside rear door handle unlocks the door but does not release the latch to open the door. The second pull releases the latch to open the door. These features are in addition to a "child safety lock." You asked whether your rear side door locking system would comply with the requirements of S4.1.3 and S4.1.3.2 of FMVSS No. 206.

Paragraph S4.1.3, FMVSS No. 206 provides:

Door Locks. Each door shall be equipped with a locking mechanism with an operating means in the interior of the vehicle.

We have interpreted S4.1.3 to require the following features. Each door must have a locking mechanism, and there must be an interior operating means for engaging the locking mechanism. (See April 10, 1987 letter to Karl-Heinz Ziwica of BMW, copy enclosed.) In your letter, there is an implication that your system has an interior means for engaging each door lock. Assuming such a means is provided, the requirement of S4.1.3 would appear to be met. Because the aspect of performance required by S4.1.3 is that the interior operating means for the door locks be capable only of engaging the door locking mechanism, S4.1.3 does not address what means must be provided to unlock the locking mechanism, and thus does not prohibit unlocking a locking mechanism by means of the "inside rear door handle."

Paragraph S4.1.3.2 of FMVSS No. 206 provides:

Side Rear Door Locks. In passenger cars and multipurpose passenger vehicles, when the locking mechanism is engaged both the outside and inside door handles or other latch release controls shall be inoperative.

Your letter did not specifically state that when your locking system is engaged both the inside and outside latch release controls would be inoperative. Assuming that they would be, the question is whether the inside door handle on your system is "inoperative" when the handle can still operate to disengage the locking mechanism. We conclude that the answer is yes. This issue was addressed in an October 7, 1993 letter to Mr. Ziwica of BMW (copy enclosed), concerning a side rear door lock and latch mechanism similar to yours. The BMW system consisted of a door handle that served the dual function of acting as a door locking mechanism and door latch release. When the side door is locked, the door handle would be pulled once to disengage the locking mechanism. The handle would be pulled a second time to open the side rear door.

In NHTSA's response to BMW, the agency stated that S4.1.3.2 is intended, in part, to reduce inadvertent door openings due to impact on or movement of inside or outside door handles. Thus, the agency concluded that "inoperative," as used in S4.1.3.2, refers to the operation of opening the door, rather than that of disengaging the lock. Accordingly, NHTSA determined that the BMW system met the requirement of S4.1.3.2.

The door handle of your system serves the same "dual function" as that of the BMW system, and thus would be permitted. The door handle of your system cannot open the door when the locking mechanism is engaged.

You asked whether the second pull unlatching the door could occur at any time after the first pull, or only within a specific time frame after the first pull. The standard does not specify that a door can only be unlatched after a certain amount of time from disengagement of the door lock. The second pull unlatching the door can thus occur at any time after the first pull.

Finally, you stated that you were concerned about the final rule of April 27, 1968, 33 FR 6465, which promulgated the rear door lock requirements discussed today. You quoted that portion of the preamble to the final rule which stated that the requirement for rear door locks was a child-protection device because it prevents opening the rear door by movement of the inside rear door handle by children. You asked us to "address this issue."

As explained above, your locking system would meet S4.1.3.2 because, when the locking mechanism is engaged, the inside door handle cannot open the door. Since the inside door handle cannot open the door when the door is locked, that aspect of performance serves as a child protection measure. However, we agree with your decision to equip the door with a child safety lock. A child safety lock, when engaged, renders the inside rear door handle incapable of opening the door. The outside door handle is operative and can be used to open the door. The lever deactivating the child safety lock is typically inaccessible to the child passenger. A child safety lock may be appropriate as an added child protection measure.

Notwithstanding the foregoing discussion, the system you describe raises serious safety concerns, in that a child could disengage the lock and then open the door by playing with the handle. The fact that your proposed system would also be equipped with a Atraditional child lock@ reduces but does not eliminate such concerns.

I hope this information is helpful to you. Should you have any further questions or desire additional information, please feel free to contact this office at this address or at (202) 366-2992.


Samuel J. Dubbin Chief Counsel


ref:206 d:3/28/96

The capability of the operating means to engage the required door locks must not be interfered with by any additional door locking device.