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Denial of Petition for Compliance Investigation

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National Highway Traffic Safety Administration (NHTSA), Department of Transportation.


Denial of petition for compliance investigation submitted by Safety Analysis & Forensic Engineering.


This notice sets forth the reasons for the denial of a petition submitted to NHTSA under 49 U.S.C. 30162 by Safety Analysis and Forensic Engineering. The petition requested that the agency commence an investigation into whether certain Ford Explorer and Mercury Mountaineer vehicles are in compliance with the requirements of Federal Motor Vehicle Safety Standard (FMVSS) No. 216, “Roof crush resistance.” After review of the petition and other information submitted by the petitioner and the vehicle manufacturer, NHTSA has concluded that further expenditure of the agency's investigative resources on the issue raised in the petition does not appear warranted. The agency has accordingly denied the petition.

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Mr. Robert Krauss, Office of Vehicle Safety Compliance, NHTSA (202) 366-5292.

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In September 2005, Safety Analysis & Forensic Engineering (SAFE) petitioned NHTSA to conduct an investigation to determine if model year (MY) 1999-2001 4-door Ford Explorer vehicles are in compliance with the requirements of Federal Motor Vehicle Safety Standard No. 216, “Roof crush resistance.” In January 2006, SAFE extended the scope of its petition to include 1997-1998 Explorers and 1997-2001 Mercury Mountaineer vehicles. Based on a thorough review of all information submitted on this matter, the agency has decided to deny the petition.


FMVSS No. 216 was promulgated in 1971 for the purpose of reducing deaths and injuries that are associated with the crushing of a vehicle roof into the occupant compartment during a rollover Start Printed Page 51664crash. This safety standard applies to passenger cars and to multipurpose passenger vehicles, trucks and buses with a Gross Vehicle Weight Rating (GVWR) of 2,722 kilograms or less. The standard does not apply to school buses and convertibles. The standard states that when a force of 1.5 times the unloaded weight of the vehicle is applied to either the driver or passenger side of a vehicle roof by a large unyielding metal plate called a platen, the roof will not crush more than 127 millimeters (5 inches). The initial contact point of the platen is typically slightly rearward of the intersection of the A pillar and the roof. In engineering terms, a vehicle roof structure is required to develop a minimum resistive force of 1.5 times the vehicle's unloaded weight during the first 127 millimeters of roof crush. Therefore, the minimum strength-to-weight ratio (STWR) for a vehicle roof tested in this manner must be 1.5.

After reviewing the SAFE petition, NHTSA invited SAFE and Ford Motor Company (Ford) to provide any additional information they believed was germane to this petition. Both companies made presentations to the agency in January of 2006. Ford made an additional submission to the agency on January 24, 2006. All submissions from both parties may be found in Docket No. NHTSA-2005-22904, which can be accessed at

There is no dispute that Ford based its certification to FMVSS No. 216 for the MY 1999-2001 4-door Explorer on five tests conducted on prototypes that were based on the MY 1995-1997 Explorer vehicles (to distinguish this from other relevant data, we will refer to these tests as Data Set 1). Ford uses the maximum possible unloaded vehicle weight (MUVW) that can be calculated for any production vehicle when determining the STWR of the roof structure for certification purposes. Ford stated that the MUVW for 1999 models was 4,700 lbs. For the 2000 to 2001 models, the MUVW was 4,600 lbs. Ford states the average STWR for the five certification tests was 1.69, with the lowest measured as 1.63. A MUVW of 4,700 lbs was used to calculate these numbers. SAFE points out that there was an eight percent variation in the resistive forces recorded for these five certification tests.

Ford conducted two development tests in 1999 using modified Explorers from the assembly line to determine if it could make a change in the way windshields were installed in the Explorer on the assembly line (Data Set 2). According to Ford, the purpose of this testing was to determine what effect using a maskless painting process may have on how the windshield would perform during a test of the strength of the roof structure. Based on the MUVW of 4,600 lbs, the STWRs for these tests were 1.51 and 1.53. SAFE notes that on one of the test reports the Ford engineer originally calculated the STWR using a MUVW of 4,700 lbs, which suggested a test failure. Ford later corrected the MUVW on the report.[1] Ford did not institute the proposed change in production and contends that these tests were not used for certifying the 1999, 2000, or 2001 models.

The last set of data (Data Set 3) presented by Ford was generated from three tests conducted for Ford by Exponent, Inc. (Exponent). These tests were conducted on used vehicles that had between 48,800 and 91,500 miles on the odometer. Two of the vehicles were from the 1999 production and one was from the 2000 production. The average STWR calculated (using an MUVW of 4,700 lbs) was 1.55 with a force variation of two percent. SAFE has discounted these tests because Ford did not conduct them at its own facility. In addition, SAFE believes that the test procedure used by Exponent was flawed. SAFE contends that the test vehicles were supported at both the vehicle frame and the sill, thus violating the wording of the standard that states, “Place the sills or the chassis frame on a rigid horizontal surface * * * ” 49 CFR 571.216 S7.1. In support of its contention, SAFE refers to a photograph of Exponent's test set-up, which it contends indicates that the sills of the test vehicle were welded to the test fixture. Ford, in its January 24, 2006 submission to the agency, states that the sills were not welded to the test fixture. It further explains that jacks were used only to support the vehicle overhangs and did not provide an alternative load path for the FMVSS No. 216 applied forces. Therefore, Ford asserts that the Exponent test procedure is consistent with the procedure it uses to conduct FMVSS No. 216 testing.

SAFE analyzed the above three sets of test data and concluded that the margin of compliance of the 4-door Explorer decreased from the time Ford conducted its certification testing. Because SAFE discounted the tests conducted by Exponent, it compared only Data Set 1 with Data Set 2. SAFE applied the eight percent variance it calculated for the resistive force of the five certification tests (Data Set 1) to the average STWR Ford provided for the second set of data, i.e., the windshield installation tests. From this calculation SAFE projected that a number of production vehicles will be in noncompliance with FMVSS No. 216.

In an effort to determine why there may have been a decrease in the margin of compliance, SAFE performed tear-down studies on a number of Explorer roofs. SAFE did not find a significant change in the roof structure from 19961/2 to 2001 MY productions. However, SAFE did find a minor change in the front door structure. Ford stated that at the time of the change both its supplier, Budd Company, and its designers relied on their collective experience with roof crush testing to conclude that this change would have little if any effect on compliance with FMVSS No. 216.

Based on the above test data sets, SAFE requested that NHTSA open an official compliance investigation. SAFE requested that NHTSA test a minimum of 10 vehicles that were produced at different assembly plants and have the largest number of options that add weight to the vehicles.


The agency has reviewed all of the data submitted by both SAFE and Ford and has decided to deny the petition for the following reasons.

First, none of the data presented indicate any of the vehicles tested failed to meet the requirements of FMVSS No. 216. SAFE did not present any data indicating that any MY 1997-2001 Ford Explorer or Mercury Mountaineer vehicles failed FMVSS No. 216 compliance testing.

Second, SAFE asserts that a segment of the 1997-2001 Explorer/Mountaineer production will not meet the standard. This assertion is based primarily on SAFE's contention that there was a decrease in the margin of compliance after Ford conducted its certification testing. SAFE bases this contention on the difference between the compliance margin calculated for Ford's certification tests (Data Set 1) and the lower margin calculated for Ford's development tests, conducted on Start Printed Page 51665modified assembly line vehicles (Data Set 2). Extrapolating from the eight percent variation in the certification tests of Data Set 1 and the lower average safety margin in the tests of the modified vehicles comprising Data Set 2, SAFE assumed that the test results of DATA Set 2 were representative of how production vehicles would perform and that those at the lower end of the presumed eight percent range in test results would not comply with the standard.

NHTSA is unable to draw the same conclusion from the data presented. Statistics taken from a group of tests conducted on preproduction development vehicles on which production vehicles were based (Data Set 1) may not logically be extrapolated to the results of testing conducted on modified assembly line vehicles where the design change never went into production (Data Set 2). The test results concerning modified assembly line vehicles (Data Set 2) are not relevant to the potential compliance of production vehicles. The windshield modifications that Ford was considering when it modified and then tested these vehicles in 1999 never became part of production vehicles. Accordingly, one cannot assume, as SAFE does here, that developmental tests concerning a new process for windshield attachment, which was never adopted for production vehicles, are representative of likely test results for production vehicles. Moreover, the variation in test results for the three used production vehicles tested by Exponent (Data Set 3) was two percent. This indicates that production vehicles, even after years of use, produced lower test variation than the prototype vehicles.

Third, all of the STWR data presented by SAFE and Ford are based on maximum possible unloaded vehicle weights for the model years in question. Ford stated that the heaviest 11 percent of the MY 1999 production (for which the MUVW was 4,700 lbs.) was between 4,450 and 4,678 lbs. The heaviest 12 percent of the MY 2000 and 2001 production (for which the MUVW was 4,600 lbs.) was between 4,380 and 4,580 lbs. Considering these production weight numbers, there are very few production vehicles that approached the MUVW. Since the STWR is the ratio of the resistive force to the unloaded vehicle weight, as the unloaded vehicle weight decreases the STWR increases. Therefore, the vast majority of Ford's production vehicles appear to have a greater margin of safety with respect to meeting the requirements of FMVSS No. 216 than the margin described in data sets 1-3, all of which indicated compliance with the standard based on the MUVW.

Fourth, SAFE requests that NHTSA test ten vehicles, but the compliance test prescribed in FMVSS No. 216 is intended to be applied to new vehicles. At this late date, NHTSA cannot obtain new MY 1999 to 2001 vehicles. Due to limited agency resources, the agency selects certain new vehicle models when it conducts compliance testing and, for practical reasons, cannot test every new model annually. NHTSA did test two earlier model year Explorers (a 1994 and 1996) when they were new. These model years met the FMVSS No. 216 performance requirement. We are not aware of design changes that occurred after the model years that NHTSA tested that would have had a significant impact on the roof strength of the MY vehicles that are addressed by SAFE's petition.

Fifth, SAFE argues that Ford made a change in the door structure of the Explorer in 1997 that allegedly resulted in reduced roof strength. SAFE has not effectively substantiated either the reduced roof strength that it claims occurred or the causal role of the door structure change in the alleged reduction. Ford offered only the collective judgment of its staff and its supplier that such a change would have had little or no effect on roof strength. Having reviewed the information that both SAFE and Ford submitted concerning that change, we have no basis for concluding that the change had any negative effect on roof strength. In any event, the only actual tests (Data Set 3) of vehicles built after the date of that change, which involved vehicles that had been in use for several years, showed that the vehicles met the roof strength standard.

Finally, efficient allocation of the agency's enforcement resources is among the criteria NHTSA may consider when deciding whether to grant or deny a petition to initiate a compliance investigation. See 49 CFR 552.8. Having fully considered all information presented by SAFE and Ford, we do not believe that the investigation SAFE wants NHTSA to conduct would be likely to lead to an agency determination that the subject vehicles do not comply with FMVSS No. 216. We believe NHTSA's limited enforcement resources are better allocated to investigations that are more likely to reveal noncompliance.


In consideration of the above, this petition for a compliance investigation is denied.

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Authority: 49 U.S.C. 30162(d); delegations of authority at 49 CFR 1.50 and 501.8.

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Issued on: August 24, 2006.

Daniel C. Smith,

Associate Administrator for Enforcement.

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1.  In its initial petition, SAFE placed great emphasis on this alleged test failure, even though it involved a vehicle modified in a manner (i.e., using a maskless paint process) that was not carried through for use in production vehicles. When the vehicle's actual MUVW (4,600 lbs) is used, there was no test failure. The record indicates that although the Ford employees conducting the test were informed of the vehicle's actual MUVW before the test, they performed calculations using a higher MUVW to determine whether the test results might be extended to a completely different vehicle with the higher MUVW on which Ford was considering using the same painting technique. After determining that the technique would not be feasible for the other vehicle, Ford personnel amended the test document to show the actual MUVW of the tested vehicle and the resultant calculations.

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[FR Doc. E6-14458 Filed 8-29-06; 8:45 am]