DATE OPENED: Nov. 27, 2001 DATE CLOSED: Oct. 3, 2002
SUBJECT: Post Rear End Collision Fires
PROMPTED BY: Ford TSB No. 01-21-14
PRINCIPAL ENGINEER: F. Borris
|MANUFACTURER: Ford Motor Company
MODEL(S): Ford Crown Victoria (including Police Interceptor), Mercury Grand Marquis, Lincoln Town Car
MODEL YEAR(S): 1992-2001
VEHICLE POPULATION: 3,128,603
|PROBLEM DESCRIPTION: The fuel tank can rupture following a high- energy rear collision resulting in severe fires. A vehicle occupant surviving the impact trauma could be killed as a result of fire intrusion into the passenger compartment.|
|FAILURE REPORT SUMMARY|
|Description of Other: Two reports were identified involving a post rear crash fire in the subject vehicles where the officer was struck and killed while standing out of the target vehicle.|
|ACTION: The Service Query is closed.|
|DIV CHF: /s/||DATE:|
|OFC DIR: /s/||DATE:|
SUMMARY: The Office of Defects Investigation opened an investigation (SQ01-014) after reviewing a Ford technical service bulletin and consumer complaints involving fuel tank punctures and fires following high-energy rear collisions in MY1992-2001 Ford Panther platform vehicles (Crown Victoria, Grand Marquis, and Town Car.) During the course of its investigation, ODI:|
For more detailed information, see the investigation closing report.
|Subject:||Fuel Tank Integrity in Rear Collisions|
|Manufacturer:||Ford Motor Company|
|Models:||Crown Victoria, Town Car, Grand Marquis|
|Date Opened:||November 27, 2001|
Background: The Office of Defects Investigation (ODI) opened a Service Query (SQ01-014) after reviewing a Technical Service Bulletin (TSB) (Ford Article 01-21-14) issued by Ford Motor Company (Ford). The TSB provides information and suggests modifications aimed at reducing the potential for post-rear crash fuel tank punctures in Ford's Panther Platform vehicles produced during Model Years (MY) 1992-2001.
Prior to the publication of the TSB, ODI received three letters from law enforcement organizations expressing concern or requesting an investigation into the potential for fuel leaks in Crown Victoria Police Interceptor (CVPI) vehicles following rear impact crashes. ODI requested additional information from one correspondent (National Troopers Coalition) and received summaries of 17 incidents alleging post rear crash fires (PRCF) in CVPI vehicles from calendar year (CY) 1983 to 2001. The summaries included allegations of 11 deaths of which 4 occurred during CY 2001. All the target vehicles involved were CVPIs and 14 were within the scope of the TSB. It stands to reason that the majority of PRCF's would occur within the law enforcement population of Panther vehicles due to their use on highways where high-energy collisions are most likely to occur. Law enforcement officers routinely pull motorists to the shoulder area exposing their vehicles to a greater risk of rear impact. A search of ODI's consumer complaint database revealed one incident involving a MY 2000 CVPI that burst into flames following a high-energy rear impact. Fortunately, the officer escaped with relatively minor injuries. Based on the above information, ODI determined that an investigation was warranted.
|Dec. 17, 1983||Officer Drew Brown fatal crash; Cobb County, GA||Earliest record of Panther platform PRCF fatality|
|Jan. 21, 1995||Ford Crash Test No. 9706, 50 mph crash of a 1989 Taurus into 1996 CV||Leakage in excess of FMVSS amount; caused by frame rail puncture (FMVSS 301 specifies a 30mph test speed)|
|Jul. 26, 1999||Florida Highway Patrol Study||Analysis of PRCFs involving Panther platform vehicles|
|Feb. 16, 2001||Ford makes presentation to Arizona Police Organizations||Statistically defends crash performance of Panther platform|
|Jun. 29, 2001||Ford meets with ODI and presents AZ presentation; offers to provide available reports||Reports on 5 incidents provided by Ford on August 10, 2001|
|Oct. 22, 2001||Ford publishes TSB||Ford also sends message to law enforcement about TSB via LAWNET|
|Nov. 27, 2001||ODI opens SQ01-014||ODI subsequently sends information request to Ford and to GM on B-Body vehicles|
Fuel Tank Description: The Panther fuel tank is steel construction and has a usable capacity of 19 gallons. The system is equipped with a fill limiting feature to provide an air space of 12-14 percent at full capacity. The tank is positioned aft and slightly above the vertical centerline of the rear axle. In essence, the fuel tank is sandwiched between the rear axle and the forward trunk wall. This is not a new concept; Ford has used this same fuel tank location in the Panther platform since the late 1970's.
The picture to the right was taken at a local police department and shows the relationship of the fuel tank to the rear axle. The distance from the tank leading edge to the differential cover ring gear bulge is approximately four inches. Also visible are the sway bar brackets and dual exhaust pipes. This vehicle is a MY 2000 CVPI.
|Grand Marquis||Town Car||All Crown Victoria||Crown Victoria
Ford TSB 01-21-14:
Although the scope of Ford's TSB includes all 1992-2001 Crown Victoria, Town Car and Grand Marquis vehicles, the focus is on law enforcement agencies who operate CVPI fleets. While it is true that the police and civilian versions of the Crown Victoria share the same fuel system and rear suspension geometry, the CVPI vehicles have a much greater exposure to high-energy rear impacts due to the nature of their use as blocker vehicles at crash scenes or during routine traffic stops along high-speed public roads. This is not to say that civilian vehicles cannot benefit in some measure from having the same modifications performed, but the vast majority of documented PRCFs in the subject vehicle population have occurred in the segment of the Panther population dedicated to police duty.
Prior to publishing its TSB, Ford had conducted a number of post crash inspections of CVPI vehicles and determined that at least one fuel tank puncture was caused by components mounted on the rear axle.
To address these two potential sources of fuel tank puncture, Ford's TSB recommended replacing the hex-headed parking brake cable bolt with a different fastener having a rounded head and grinding the U-bracket tabs flush, leaving no sharp edges.
TSB Dissemination Efforts:
Ford indicated in its April 29, 2002 response to ODI that it met with at least three law enforcement agencies to discuss the TSB (Massachusetts State, Connecticut State, and City of Phoenix Police Departments). Additionally, Ford representatives introduced the TSB at two conferences at which it believes hundreds of law enforcement personnel were in attendance. Ford has also transmitted information on the TSB through law enforcement communications networks via the Michigan State Police onto the "LAW NET" system. Ford also states that its fleet hotline has received over a hundred contacts regarding the TSB and has responded directly to each law enforcement agency that made an inquiry.
Federal Motor Vehicle Safety Standard (FMVSS)
No. 301, Fuel System Integrity:
FMVSS 301 is intended to reduce deaths and injuries occurring from fires that result in fuel spillage during and after a motor vehicle crash. With regard to rear-impact crashes, FMVSS 301 requires that a stationary vehicle withstand an impact with a flat, 1,814 kg barrier moving at 48 km/h (30 mph) and not leak fuel in excess of 28g from impact until motion of the vehicle has ceased. Additionally, the vehicle shall not leak fuel in excess of 142g in the 5-minute period following cessation of motion.
Ford has established Safety Design Guidelines under which the company designs its vehicles not only to meet or exceed all applicable laws and regulations, but also to advance the state-of-the-art where practicable (see Ford Letter dated 2-1-84). Ford conducts fuel system integrity testing of its pre-production models at greater energy levels and under more severe conditions than that required by FMVSS 301. For example, Ford conducts rear impact testing with a moving barrier of similar mass and geometry as specified in FMVSS 301; however, Ford increases the impact speed to 56.4km/h (35 mph) representing a 16.6% speed increase or, more importantly, a 36.1% increase in energy at impact. Ford also conducts vehicle-to-vehicle rear impact testing at 80.6 km/h (50 mph) where the bullet vehicle (typically a Taurus) strikes the target vehicle at what Ford believes is the most severe point of impact (i.e., 50% offset towards the fuel filler side of the vehicle).
Ford indicated in its response to ODI that the subject vehicles not only meet but exceed the requirements of FMVSS 301.
Ford has made the following design changes affecting Panther Platform fuel system integrity:
Comparison to GM B-Body:
From MY 1985 to MY 1996, GM produced over 1.7M of its B-Body vehicles (Caprice, Impala). Like the Panther vehicles, the GM B-Body vehicles are rear wheel drive, four door sedans of similar weight. GM sold a similar percentage of the total B-Body production (15% vs. 14% for Panther) to law enforcement organizations. Thus, the B-Body is the most comparable vehicle to the Panther for peer analysis.
GM Vehicle Populations:
|Model Year||All B-Body||B-Body w/SEO|
MY 1996 Vehicle Specifications
|Crown Victoria (Panther)||Caprice Classic (B-Body)|
|Wheel Base (in.)||114.4||115.9|
|Curb Weight (in.)||3,800||4,036|
Like the Ford Panther vehicles, the GM B-Body stores its fuel in a tank mounted aft of the rear axle. But unlike the Panther's vertically mounted steel tank, the B-Body tank is made of plastic (HDPE) and is horizontally mounted below the trunk floor. As illustrated in the photographs below, the GM fuel layout strategy presents less of the tanks leading edge toward the rear suspension components at the expense of being further within the vehicle's crush zone.
Panther Fire Reports:
ODI has identified 26 reports of Panther fires following a high-energy rear impact crash with either another vehicle or a stationary object. These reports span approximately September 1992 to August 2002 and do not include reports involving vehicles outside of the scope of Ford's TSB. Information regarding these incidents was obtained from Ford, the 1999 Florida Highway Patrol Study, plaintiffs' attorneys, news media, and ODI records. Of the 26 reports, 22 involve law enforcement vehicles (CVPI) and 4 occurred during civilian use. A fatality resulting from thermal injuries is alleged in 16 of the 26 reports along with 4 reports of serious burns. Estimates of bullet vehicle impact speeds range from 55 to 85 mph. The mass of the bullet vehicle also varies greatly from a relatively light 1997 MY Honda Prelude at roughly 3000 lbs. to a 1999 MY International tractor-trailer partially loaded at 48,000 lbs. Some of the reports alleged that the front passenger door was jammed shut by the force of impact, further decreasing the likelihood of escape.
Fuel Tank Failure Mode:
Information concerning the fuel tank failure mode is not readily available for 11 of the known reports. However, the parking brake cable bolt is alleged to be a contributing factor in 7 reports. Other alleged sources of fuel tank failure include:
B-Body Fire Reports:
As indicated above, ODI also requested information from GM using the same criteria as that requested from Ford. From a review of GM's response and the Florida Highway Patrol study mentioned above, ODI identified 11 reports including 6 (55%) law enforcement vehicles and 5 vehicles in civilian use. These reports span 11 calendar years from 1989 to 1999 and resulted in 6 fatalities and 5 injuries. No specific fuel tank failure mode information was provided with these reports.
Fatality Analysis Reporting System (FARS):
FARS is a census of all fatal crashes occurring on public highways in the United States. ODI conducted a recent search of the FARS database for the MY 1992 -2001 Panther models, including both civilian and law enforcement, where the initial impact point was equal to 5, 6, or 7 o'clock. This search was repeated for the GM B-Body models from MY 1985 -1996. For the period covering calendar years 1992 to a portion of 2001, the subject Panther vehicles are reported as having 21 fires out of a total of 267 fatal rear crashes yielding a fire/fatal rear crash ratio of 21/267 or 8.0%. Similarly, for the same period of time, the B-Body vehicles are reported as having 12 fires out of a total of 190 fatal rear crashes for a ratio of 12/190 or 6.3%.
"Florida Highway Patrol (FHP) Rear End Collision Study of 1999":
This study was conducted by Florida's Bureau of Law Enforcement Support Services and was completed on July 26, 1999. A total of 32 crashes involving 13 law enforcement vehicles were analyzed of which 23 were from the FARS database. The models and model years selected were the 1992-1997 Ford Crown Victoria, the 1991-1996 Chevrolet Caprice, the 1985-1997 Ford Taurus and the 1989-1997 Chevrolet Lumina. These populations were selected because all of these vehicles were sold with a police package as an option. The two front wheel drive models (Taurus and Lumina) both have the fuel tank located forward of the rear axle, while the opposite is true for the two rear wheel drive models.
In order to compare the risk of a PRCF, the study used sales figures and reports from FARS of fatal crashes involving fire. An estimate of MY 1997 sales figures was made for the two Ford models based on previous sales trends since the actual figures were unavailable at the time. The study determined that the CVPI and B-Body were comparable based on the then-current FARS data with fatal rear-end crash rates with fire per 100,000 vehicles of 0.427 and 0.431 respectively. The Taurus (0.089) and Lumina (0.115) rates were significantly lower, but some of this difference may be attributed to differences in the service environment between rear wheel and front wheel drive vehicles. Specifically, law enforcement officers tend to use the rear wheel drive vehicles in greater numbers for duty on high-speed roadways, exposing this population to a greater potential for high-energy rear impacts.
California Highway Patrol (CHP):
ODI contacted the CHP in April 2002 while conducting an informal survey to ascertain the law enforcement community's awareness of Ford's TSB. The CHP contact provided the following approximations regarding the CVPI field performance. The CHP operates a fleet of 4,200 vehicles including 2700 CVPI vehicles. Vehicles in the CHP fleet are retired after 40-42 months of use. The CVPI fleet averages 55-60 million miles of highway use per year or 20.3K miles per vehicle per year. It is common for the CHP to average one rear impact collision per week resulting in a CVPI vehicle being totaled. The average impact speed for these crashes is between 45-55 mph, but some are significantly greater. According to the CHP representative's memory, there were only two incidents in the past few years of fuel tank failure following a rear crash. One of the two resulted in a fire and fatality.
In connection with a product liability lawsuit, Ford contracted with an independent test facility in February 2002 to conduct high-energy crash testing of three Ford Crown Victoria vehicles and one Chevrolet Caprice. In each test, the target vehicle was parked in neutral on level ground at 95% fuel system capacity (with Stoddard solvent). For each of the vehicle-to-vehicle crashes, the bullet vehicles were positioned such that the front bumper centerline of the bullet vehicle impacted the rear bumper of the target vehicle 23 inches to the left of the target centerline.
|Speed (mph)||Fuel Leakage?||Remarks|
|7148||1996 Crown Vic (OEM)||Moving Deformable Barrier (MDB)||50.2||None / 30 min||No fuel loss for 30 minutes|
|7142||1996 Crown Vic (OEM)||1995 Nissan Altima||70.4||15.7oz / 20 min||Fuel loss around filler pipe, no TSB component punctures|
|7156||1996 Crown Vic
(with plastic shield and TSB performed)
|1995 Nissan Altima||71.6||117oz / 30 min||Fuel loss from small hole at lower left seam and at filler pipe|
|7153||1996 Caprice||1995 Nissan Altima||72.4||328 oz / 24 min||Fuel loss at filler pipe and from right rear lower surface|
Crash Test 7156 (Crown Victoria) showing severe penetration.
Crash Test 7156 (Crown Victoria with TSB modifications) showing crushed fuel tank with a black polymer shield installed.
The photograph below was taken during Crash Test 7153 (Caprice) and shows severe
penetration and resulting leakage.
Crash Test 7153 (Caprice) showing severe deformation of fuel tank.
On February 8, 2002 Ford submitted the following comments in response to ODI's Information Request Letter:
...the rear impacts that have resulted in fuel leakage have been so severe that it is likely that similar vehicles from any manufacturer would also experience fuel leakage in similar impacts.... The impacts that were resulting in fuel leakage were occurring at extremely high closing speeds, almost always above 60 miles per hour with some as high as 84 miles per hour, and frequently involved heavy and rigid vehicles, such as pick up trucks, or even larger and heavier commercial vehicles, such as dump trucks or tractor trailer vehicles.
No vehicle or fuel system design can completely eliminate the risk of fuel leakage in extremely severe collisions.
During the course of this investigation, ODI received a report of a fatal crash with fire involving a Chandler, Arizona police officer. According to a press release from the Chandler Police Department, the officer was driving a subject CVPI that erupted in flames after striking a traffic signal pole. ODI sent an investigator to Arizona on June 26, 2002 to inspect the CVPI and three other Arizona-based CVPI vehicles involved in earlier PRCFs. ODI met with staff from the Arizona Department of Public Safety (DPS) and reviewed crash documents including eyewitness statements, reconstruction reports, and photographs.
Chandler Crash: Officer Robert Nielson was killed in the line of duty while responding to investigate a traffic collision on June 12, 2002. His MY 1999 CVPI was traveling westbound at an estimated 76mph and carrying a half tank of fuel when it was struck on its left rear by an eastbound MY 1999 Mitsubishi sedan. The initial impact tore the left frame rail apart and ripped the left side axle and housing out of the center differential housing. The impact sent the CVPI into a counter-clockwise rotation until it struck a traffic signal pole on its left rear quarter panel behind the rear axle. There was approximately 47 inches of crush damage to the right side of the vehicle, centered just rearward of the axle and in line with the fuel tank. An inspection of the tank revealed three sources of fuel leakage: a small hole caused by the differential housing, a large hole caused by the right fuel tank strap mount, and another small hole from an unidentified object in the trunk. The Ford TSB modifications had been performed on this vehicle.
The picture at left of the Nielson fuel tank shows the severe crush concentrated on the right side. This would result in an immediate loss of volume and corresponding increase in internal pressure.
The picture at right shows the underside of the Nielson tank reinstalled in the vehicle.
The area inside the red circle shows the largest hole caused by the right fuel tank strap mount. The small area of daylight visible through this hole is from the fuel filler pipe opening.
ODI also inspected two other PRCFs that occurred during the course of this investigation. In July 2002 near Atlanta, Georgia, a MY 1998 CVPI operated by Cobb County Police was struck in the rear by a MY 1997 Mack tractor-trailer operated by the US Postal Service traveling at approximately 55 mph. The officer was able to escape the vehicle via the right side front window. An inspection of this vehicle was conducted on July 16, 2002. A visual inspection of the vehicle indicates that the fuel tank was punctured in at least two locations. The larger of the two punctures was caused by the left, lower shock absorber mount. A smaller hole appears to have resulted from the edge of the differential cover.
Another MY 1998 CVPI was struck from the rear on August 5, 2002 near Buffalo, NY by a 2002 Chevrolet pickup truck hauling a gooseneck cattle trailer at an estimated speed of 55 mph. The officer was rendered unconscious by the force of the impact but was removed from the burning vehicle by nearby witnesses before suffering serious injury. A contractor working on behalf of ODI inspected the vehicle and determined that at least one puncture of the fuel tank was caused by the left sway bar U-bracket. Although the Ford TSB recommendations had been performed on this vehicle, the U-bracket made contact with the tank along an edge other than the area ground away in accordance with the TSB.
After the Nielson crash, Ford began working with the Arizona Attorney General to develop its CVPI Police Officer Safety Action Plan (POSAP). The POSAP is a joint effort by Ford and the law enforcement community to address the entire spectrum of work practices and equipment that protect law enforcement personnel from PRCFs. Three major components comprise the Plan: the formation of a Blue Ribbon Panel, the formation of a Technical Task Force, and efforts aimed at improving communication between Ford and local law enforcement agencies.
The Blue Ribbon Panel is tasked to identify best practices to help avoid crashes and improve officer safety by focusing on issues such as vehicle visibility, use of vehicles as barriers, and police procedures during traffic stops. The panel is comprised of nine members: four appointed by the Arizona AG; four appointed by Ford; and the remaining position will be reserved for the chair of the Technical Task Force.
The Technical Task Force was tasked to study crashworthiness issues for the CVPI that may include: bladders (see Figure below), shields, trunk usage, fire suppression, and test development. It is comprised of Ford engineers and fuel system experts in addition to selected outside technical experts, including representatives from the military and the racing and aviation industries.
Ford indicated that it has conducted tests of fire suppression materials and is partnering with experts in this field. Although earlier reports from Ford indicated that fuel bladders would be evaluated by the Technical Task Force, Ford stated that it has been unable to initiate testing as of this time.
On September 27, 2002, Ford announced a series of actions aimed at enhancing police officer safety and improving communication.
Center for Auto Safety (CAS) Petition:
On July 22, 2002, the CAS petitioned NHTSA to upgrade SQ01-014 to an Engineering Analysis and to expand the scope of its investigation to include all fuel-fed post crash fires in the subject vehicles regardless of the source or direction of impact. ODI conducted searches of the FARS database for information on all MY 1992-2001 Panther vehicles and all other sedans (AOS) for fatal crashes involving fire. These searches included all impact locations and were executed once including police vehicles and once excluding police vehicles.
Expressing the risk of fire as a ratio of fires in fatal vehicles per total fatal vehicles yields a ratio (including police vehicles) of 0.033 for both the Ford Panther and AOS. Excluding police vehicles yields a ratio of 0.029 for the Ford Panther versus 0.033 for AOS. These results indicate that the subject vehicles are not over-represented with respect to the risk of fire in high-energy crashes.
The available information regarding fuel tank failure mode, the risk of fire per fatal crash, field performance, and crash testing indicate that the performance of the subject vehicle in high-energy rear crashes is not unlike that of the most comparable peer vehicle, the GM B-body.
Reason for Closing:
Under the present circumstance, it is unlikely that further investigation would produce sufficient evidence to demonstrate the existence of a safety-related defect in the subject vehicles. Therefore, this investigation is closed based on the evidence available at this time. The agency reserves the right to take further action if warranted by new or changed circumstances.
NHTSA will continue to monitor efforts by Ford and other parties to enhance the safety of law enforcement officers in motor vehicle crashes. To direct even more attention and resources to this issue, the agency is entering into a collaborative partnership with the International Association of Chiefs of Police (IACP). NHTSA anticipates that this cooperative effort will study such issues as emergency vehicle lighting configuration and their effect on crashes; placement of police vehicles during traffic stops; after-market equipment placement on officer safety; the use of sport utility vehicles as police vehicles; and safety issues associated with the use of other types of "non-traditional" vehicles for law enforcement purposes. NHTSA believes that this effort, coupled with the work of the Ford/Arizona Blue Ribbon Panel and Technical Task Force describe above, will help build a compendium of best practices to promote police vehicle safety.
 A total of 18 fatalities are associated with the 26 known reports of Panther fires. One particular crash resulted in the death of three civilian passengers seated in the rear row of seats. Additionally, two police officers were struck and killed by the bullet vehicle while they were standing outside of their respective Panther vehicles which were also struck and ignited.