[updated:LAST EDITED ON 18-Jun-02 AT 10:34 AM (EST)]I have been wondering and looking along with thinking about all the problems with the Crown Vic and how many police offiders that have died or got severly burned down here in AZ.
I am not an engineer but the problem looks fairly simple.
1) the tank is made of aluminum so grinding down the sharp edges of the frame is not going to stop the tank from rupture or create a spark when it hits the frame.

2) years ago when emmissions became such a big deal the fuel systems have gone to a sealed system and they put the fuel pump in the tank.
Aluminum may not cause a spark when hit but it does conduct electricty very well and when the fuel tank is struck or crushed the fuel pump becomes disconnected and creates a short which in turn creates a spark along with the heat down here in AZ and the sealed fuel system the fuel in the tank expands and creates alot of fumes.
which we all know the fumes have a lower flash point than the liquid state of gasoline. Along with that thought take a look at Nascar you will never see a electric fuel pump in a Nascar because if the threat and danger of a spark. They all use mechanical fuel pumps.
Also when the Crown Vic gets rear ended every accident I have seen on the news of these law enforcement officers getting killed or burned you can see there was obviously a higher than posted rate of speed involved and since I live here in AZ I know first hand that 98% of the people that drive down here DO NOT drive the posted speed limit it seems everyone drives atleast 50-55 mph even thru town.

But when you mix the AZ heat along with warm gasoline and fumes with an electric fuel pump in the tank. the car gets struck the fuel pump shorts out createing a very small spark which is all it takes to ignite gasoline fumes and the heat of the engine from the car that struck the Crown Vic along with the ruptured fuel tank spilling gasoline out is when you have the fire. It is a combination of those things I believe. Not the design of the car structure.

All the accidents involving these Crown Vic's that have burst into flames occured when the law enforcement vehicle was at a stand still not while moving.

This is just my $0.02 worth but it doesn't seem that hard to figure out.

 

Well, the last accident involving the 25 year old officer in Chandler was a moving accident. He was not stationary when the accident occured, he was hit and the car spun into a light pole and caught fire. The electric pump in the tank, true, they could be mounted externally, but you couldn't get a mechanical pump like you have on the NASCAR cars. If I'm not mistaken, NASCAR runs carbs still, the FI systems on new cars run at higher pressures than a carb system. Plus, electric pumps are superior to to mechanical in keeping things suh as vapor lock under control. Most every new car and truck on the road today have intank fuel pumps, but those cars aren't all out exploding like the Crown Vic has, so I don't that's a huge problem. If it was, then we should have far more similar accidents. Yes, most of the accidnets involved the car being rear ended at high rates of speed. The PHX officer burned 2 years ago was rear ended at 100 mph, most cars would have a problem not bursting into flame with that kind of impact.

By The Way, has everyone heard that the City of Phoenix has suspended a 4 million dollar order for more Crown Vics from Ford until Ford addresses the problem more. The city is calling for a fuel bladder in the tank to help control the loss if gasoline in the event of an impact.

Gary
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1946 pickup-ongoing project
1946 pickup-waiting for resto.
1947 pickup-parts truck
1957 Ford FL 500 Town Victoria
1970 Mustang FB-daily driver
1972 Olds Vista Cruiser-4 sale
1988 Bronco II-for sale

 

This may spark an arguement but being an engineer myself I know first hand about problems with vehicles. Even if a problem is identified in the first place, if a stamping die for the gas tank has already been made and parts are in production, there has to be a MAJOR, MAJOR reason to change something. Unfortunately if it costs too much it will not be done. Now I know you all are going to cry foul about money and how much human life is worth, but unfortunately that is the way the bean counters see it. EVERY single day I am pressured into doing the job I do cheaper, not better, not higher quality, not safer, but yes, cheaper.
I would wait until the cause of the fires in confirmed before re-engineering the car. And remember one more thing, NASCAR teams put hundreds of thousands of dollars into EACH car. It just is not feasable to do the same with police cars. I for one do not agree with this practice, but alas I am just a lowely engineer, not a manager or a bean counter.

 

First I am sad that accidents like this occur, and express my condolences to the familys and friends of the victims.

I am a physicist by education and a computer "engineer" by training, and a vehicle hobbyist (not hacker) for several decades. I'm not bragging, actually I make a lot of mistakes - but the combination of my education, vocation, and interest in hands-on projects helps me have a good understanding of the physical/electrial/electronic workings of most things.

I agree that whenever a death or serious injury occurs, there is justification for an investigation of the causes, and efforts of prevention of future similiar incidents. However, too often emotion gets in the way of logic, and "fixes" are demanded, even legislated, which not only don't improve the situation, but may open avenues of other disasters.

I do not believe that the electric fuel pump caused the spark which ignited the tank. Here's why: 1 - The inertia switch should have disconnected power from the pump at impact. 2 - Even if there is power to the pump, a wire would have to be severed in order to create a spark. 2 - The oxygen content in the tank is too low to ignite until the tank has ruptured and the fuel dispersed.

A more logical approach is that the tank ruptured, spilling fuel on a large area, and at the same time some of the other steel parts of the vehicle rubbed together or against the pavement, causing a spark, which then ignited the widespread fuel/fumes. It is just as likey that at impact, some other wiring was made "hot" such as the brake or tail lights, and one of these wires could have then been severed, causing the spark. But the most likely source of spark is scrapeing metal against something.

Here are my proposed solutions to the being-rear-ended-while-stopped incidents:

1 - If at all possible, don't park on a shoulder next to high speed traffic. If making a routine pull-over, the policeman should follow to an exit ramp or other safety zone before pulling over an offender.
I have seen people pulled over for minor infractions in rush-hour on the freeway. Enough on that....

2 - Have the fuel tank (at buyer's expense for special purpose vehicles, i.e police) wrapped in a fire-extinguishing foam filled blanket during assembly.

The bottom line is that we are all responsible for our own safety. We must take the first and last possible steps to prevent an accident, and reduce injury, if the accident is not preventable by us.

Again, I feel for the losses.


Winford

 

Winfordr, what you say makes sense. I'm not an engineer or Ford rep. The only weak part of your points was having the patrol car take the off ramp. I know I've seen Troopers sitting there at the side after a pull over and I've thought it would be safer for them if they were someplace else. But that in most cases is not possible. And I know I would rather sit in a Crown Vic than a front wheel drive vehicle and be rear ended any day.

With that said, how about the C130 that lost it wings fighting fires? Now that is horrific. The C130 has been in production and use nearly longer than I've been alive. They lost this plane and they grounded the fleet of C130 firefighters. I'm sure the lawyers are lining up as a result to sue Lockheed/Martin.

 

As i mentioned in another post:

Some of you guys and gals fail to realize all the gear crown vics carry in the trunk(i heard something like 300lbs fully loaded) and don't forget that some of that stuff can be explosive and/or harmful to the trunk and might be able to puncture(spikes stickes) the gas tank. And thus a very high risk for explosions.

That is probably one of the most logical explantations for this problem.


82' Flareside: zoom zoom doesn't even begin to describe it
2/4 Drop
Soon to have 325hp 351 Clevo
(maybe more,in a 3600lb truck)
Backed by a C6 with a 2000 rpm stall and a 3.50 9 incher
American Racing AR-23 (series 23) wheels
Upgraded interior
Soon to install: Sony Xplod stereo

 

I don't see how the C130 manufacturer can be liable, although they may go broke proving it. This has to be a maintenance issue (or lack of it). I used to live about a mile from the facility that refurbished c-130's (Lake City, Fl), and watched them fly those big birds around my house at low altitudes in awe.

They have been around too long and done too many critical missions to have an engineering flaw that would let the wing fall off. Of course I am speculating, but I have a tough time believing it could be anything but maintenance slackness.


And back to the CV parked on the shoulder issue, I know it is not always possible to get off the road, my point is, only park on the shoulder of a hi speed highway when there is a serious enough violation to merit it.

Winford