ArvinMeritor, Inc., Denial of Petition for Decision of Inconsequential Noncompliance

ArvinMeritor Inc. (ArvinMeritor) has determined that certain automatic slack adjusters assembled by the petitioner in 2004 do not comply with S5.1.8(a) and S5.2.2(a) of 49 CFR 571.121, Federal Motor Vehicle Safety Standard (FMVSS) No. 121, “Air brake systems.” Pursuant to 49 U.S.C. 30118(d) and 30120(h), ArvinMeritor has petitioned for a determination that this noncompliance is inconsequential to motor vehicle safety and has filed an appropriate report pursuant to 49 CFR part 573, “Defect and Noncompliance Reports.” Notice of receipt of the petition was published, with a 30 day comment period, on May 17, 2005 in the Federal Register (70 FR 28352). NHTSA received two comments.

Affected are a total of approximately 187 automatic slack adjusters assembled between October 13, 2004 and December 20, 2004. S5.1.8(a) is applicable to trucks and buses, and S5.2.2(a) is applicable to trailers. Both sections are titled “Brake adjuster,” and both require that:

Wear of the service brakes shall be compensated for by means of a system of automatic adjustment. When inspected pursuant to S5.9, the adjustment of the service brakes shall be within the limits recommended by the vehicle manufacturer.

ArvinMeritor states that the noncompliant automatic slack adjusters were assembled with housings supplied by TaeJoo Ind. Co., Ltd., and these housings were below the dimensional specifications. The petitioner states that as a result, there is interference between the automatic slack adjuster pawl and the housing cavity in which the pawl is positioned, preventing the pawl from properly engaging the actuator, which can result in a reduction or elimination of the automatic adjustment function as required by S5.1.8(a) and S5.2.2(a).

ArvinMeritor believes that the noncompliance is inconsequential to motor vehicle safety and that no corrective action is warranted. ArvinMeritor states that it has conducted dynamic testing of vehicles simulating the affected automatic slack adjusters and based on the results of this testing, ArvinMeritor is satisfied that the braking systems will still halt a vehicle within the stopping distances required by FMVSS No. 121.

NHTSA has reviewed the petition and has determined that the noncompliance is not inconsequential to motor vehicle safety for the following reasons.

First, we believe that out-of-adjustment brakes present a significant safety concern. As indicated in NHTSA's October 20, 1992 final rule establishing automatic brake adjuster requirements, “When brakes are under-adjusted, stopping ability is reduced and the probability of a crash is increased. When brakes are over-adjusted,* * *the possibility of a crash [is] increased as a result of excessive lining wear, wheel lock, or brake drum cracking. Such improper brake adjustment contributes to a significant number of crashes, including those in which vehicles are unable to stop in time and those in which there are ‘runaways’ on steep mountain grades” (57 FR 47793 at 47794).

Second, ArvinMeritor's testing showed no major degradation in stopping distance of trucks with temporarily disabled slack adjusters. However, their data did not address long-term effects of non-functioning slack adjusters on braking performance. Because automatic slack adjusters are designed to address degradation of braking performance over time, we believe that the petitioner's test results are not persuasive.

The agency received two public comments. The first commenter, Freightliner LLC (Freightliner), supports the petitioner's belief that the noncompliance is inconsequential to safety based on three points.

First, Freightliner says that the potential failure rate for these automatic slack adjusters is below Freightliner's warranty rate for this type of component.

NHTSA cannot determine that a noncompliance is inconsequential to motor vehicle safety because a potentially serious safety failure occurs relatively infrequently.

Second, Freightliner states that it instructs drivers of the vehicles to conduct a visual inspection of the slack adjuster, brake free stroke, and brake adjustment on all axles daily; thus any failure of the slack adjuster would be identified through this daily inspection.

NHTSA cannot determine that a noncompliance is inconsequential to safety because of recommended maintenance procedures or instructions established in response to a potential safety hazard. Among other things, we have no assurances that drivers would in fact follow Freightliner's visual inspection instructions.

Third, Freightliner states that it agrees with ArvinMeritor's contention that the affected vehicles will continue to meet the stopping distance requirements of FMVSS No. 121 even in the out-of-adjustment condition.

As explained above, we cannot accept Freightliner's argument because the tests conducted by the petitioner did not show that the noncompliance would not negatively affect braking performance over time.

The second comment suggested that the agency deny the petition but did not elaborate.

In consideration of the foregoing, NHTSA has decided that the petitioner has not met its burden of persuasion that the noncompliance described is inconsequential to motor vehicle safety. Accordingly, ArvinMeritor's petition is hereby denied.

Authority: (49 U.S.C. 30118, 30120; delegations of authority at CFR 1.50 and 501.8)