Interpretation ID: nht93-8.12

DATE: November 15, 1993

FROM: Thomas D. Turner -- Manager, Engineering Services, Blue Bird Body Company

TO: John Womack -- Acting Chief Council, NHTSA

COPYEE: Ben Newberry; Jim Swift

TITLE: Request for Interpretation; REF: 49 CFR Part 571 - Docket No. 90-05; Notice 4, FMVSS 222, Final Rule on Wheelchair Securement Devices and Occupant Restraint Systems

ATTACHMT: Attached to letter dated 3/25/94 from John Womack to Thomas D. Turner (A42; Std. 222)

TEXT:

Section S5.4.3.2 of the referenced final rule requires that each wheelchair location have at least one anchorage for the upper torso restraint and at least two floor anchorages for pelvic and upper torso restraint.

Section S5.4.3.2 of the rule states:

"Each wheelchair occupant restraint floor anchorage shall be capable of withstanding a force of 13,344 Newtons applied as specified in paragraphs (a) through (d). When more than one wheelchair occupant restraint share a common anchorage, the anchorage shall be capable of withstanding a force of 13,344 Newtons multiplied by the number of occupant restraints sharing that anchorage."

It is our understanding that the phrase, "When more than one wheelchair occupant restraint share a common anchorage, . . . ." is intended to address the possible situation where restraints from two different wheelchair occupant restraint systems share a common anchorage. It is not intended to address the common situation where the lower end of an upper torso restraint joins the pelvic restraint and goes to one of the rear floor anchorages of a single occupant's restraint system.

If the phrase was intended to apply to the latter, common situation, then rear floor anchorage could be required to be capable of withstanding a force of 13,344 newtons for the upper torso restraint plus 13,344 for the pelvic restraint for a total of 26,688 Newtons (6000 lbs). If the floor anchorage was also as one of the wheelchair securement anchorages, as is typically the case, Section S5.4.3.2(e) would require that the anchorage be capable of withstanding 3 x 13,344 Newtons (9000 lbs) total.

Blue Bird believes that the phrase referenced above was not intended to require double loading of an anchorage if the anchorage is intended to secure only one occupant. Referring to the attached drawings of two typical systems, we believe the following force capability requirements apply to the floor anchorages:

Left front floor anchorage - 13,344 Newtons (3000 lbs) because only one wheelchair securement device is attached.

Right front floor anchorage - 13,344 Newtons (3000 lbs) because only one wheelchair securement device is attached.

Left rear floor anchorage - 2 x 13,344 Newtons (6000 lbs) because both the left side of the pelvic restraint and the left rear wheelchair securement device are attached:

a. For Figure 1 through separate belts.

b. For Figure 2 through a common belt.

Right rear floor anchorage - 2 x 13,344 Newtons (6000 lbs) because the right side of the pelvic restraint and the lower end of the upper torso restraint are for only one occupant and along with the right rear wheelchair securement device are attached:

a. For Figure 1 through separate belts.

b. For Figure 2 through a common belt.

It is our understanding that the intent of Sections S5.4.3.2 and S5.4.3.2(e) of the standard, for single occupant systems as illustrated in figures 1 and 2, is for the rear anchorages to be capable of withstanding 2 x 13,344 Newtons (6000 lbs) rather than 3 x 13,344 newtons (9000 lbs).

Blue Bird is in the final stages of certification testing of several systems and must complete our work immediately in order to meet the January 17, 1994 effective date. We, therefore, request urgent attention be given to this matter and that confirmation of our understanding, as stated above, be provided by FAX or telephone in the next few days. A formal written interpretation can be provided at a later date, but we need the answer immediately.

Thank you for your consideration of this urgent request.

ATTACHMENTS

Figure 1 - Typical wheelchair securement and occupant restraint system (separate belts to floor anchorage)

Figure 2 - Typical wheelchair securement and occupant restraint system (single belts to floor anchorage)

(Graphics omitted)