In 1994 Benetton had a flash fire during refuelling at the Hockenheim race. The team were blamed for causing the fire by removing a filter from the fuel filler system. That wasn’t the reason for the fire. A lot of what went on is cloaked in secrecy. What really happened and why did subsequent events unfold as they did?

ADDITION - June 2016 - Anyone who worked in F1 at this time - I hear from two sources that there were major problems with swarf and nozzle blockages from the manufacturing process - in the new fuel rigs - can anyone confirm this to me? Before I explain more I'd like more confirmation. If this is true it would explain why the manufacturer of the rigs would be extremely keen to avoid information going public.

Addition - End Sept 2016- here is a mechanics view of life in F1 reflecting a bit on those days - it would be interesting for anyone wanting to be a mechanic.

Let’s start with a few caveats. I ran the aero group and wasn’t directly involved. However, we were working in what was then a small team both compared to the established teams of the time and more so compared to the teams of today. Naturally, as one of the leaders of the team, I wanted to know what was going on and asked the people in the know what was happening. I’ve checked my memory with some former colleagues and some documentation I’ve been able to find. Here’s my recollection of what really happened.

A filter was removed. It was a sort of metallic mesh, a bit like an insect screen you would use on windows but heavier duty. It was not capable of stopping the size of particle that caused the fuel nozzle to jam.

What actually caused the seizure? A tiny particle about 1/40th of the size of solids that would have been stopped by the filter that was removed.

So now we have to learn a bit about the politics of F1 at the time. Me, I find it really interesting how a subset of the pertinent facts are presented to argue one side’s case without a mention of the other vital subset of information which may provide clarity. In my view the team, i.e. Benetton, the FiA and Intertechnique (the refuelling equipment providers) all seem to me to have been guilty of that.

Benetton did not have written permission to remove the filter - fact. However, the Ligier team did and team boss “Flavio” (don’t know if it was him or if he was acting for another party such as the Benetton family) had bought into Ligier who were in financial trouble. So the team knew about permission to remove a filter. Did they gain an advantage from it – yes but less than the 1 second claimed by an “independent witness”. Ligier (French and not at the front of the field) had been given permission by Intertechnique (also French) to remove the filter. If I was running Benetton I would also have used this communication technique to get the answer I wanted. As a winning team you’re much less likely to be granted a favour than if you are a backmarker. That was clever, but the information should have come out immediately when there was the fire. I guess Benetton didn’t want the link to be made too public for other reasons. I will explain that a bit later.

All images copyright Arther Thill, World Press.

Why the seizure? All parts are made to a tolerance and, unfortunately for Benetton, the parts they had been allocated included two sliding parts where the manufacturing tolerances combined to minimise clearance such that a really tiny particle caused the system to jam.

All manufactured parts are designed to a size and the manufacturing process has a tolerance. At the design stage an acceptable level of tolerance is given as part of the design. This gets a bit trickier when there are several stages to a manufacturing process, especially if it includes stages such as hard anodising. Aluminium hard anodising adds material – just a few microns but if you do that to a rod that fits into a tube and both are anodised the design clearance can be significantly reduced.

I remember at the time the engineers coming back from discussions with the rule makers which indicated that, if we claimed the refuelling rigs were unsafe (i.e. there was a design or manufacturing fault), then we would be charged with bringing the sport into disrepute.

Paris and the FiA hearing. The engineers (along with lawyers and bosses) went with all the facts laid out. A copy of the letter from Intertechnique to Ligier, an animation of the particle sizes that the filter would have stopped and the size of particle that caused the problem. Design information about the parts that jammed and precise inspection information that showed the part tolerances were really on the limit that would facilitate this particular pair of parts jamming. You can imagine that the hole in the outer tube was a bit too small and the inner part was a bit too big. Small details but very, very important. The team (engineers) never got their opportunity to present the information.

On returning from Paris, the engineers told me the story that, during the evening before the hearing, the team boss got a call from someone very high up at the FiA. I know who of course but could not possibly mention any names. It was explained that, if the team went ahead with their defence, they would be found guilty and face harsh penalties. However, if they played along they would be given a slap on the wrist and allowed to continue to compete. The boss “did the deal” and the engineers were told in the morning. I asked myself at the time – why the hell didn’t the team get the chance to present their case? I believe that the FiA didn’t want word to get out that the rigs might be unsafe – you can imagine it would not have gone down well with other teams or with the public. Refuelling had been brought back in to spice up the show but the fire wasn’t positive publicity for those that had pushed the rule change through. By the time of the Council meeting Intertechnique had figured out what the real reason for the fire was and there was time to check all rigs and put right any potential problems. So in a way it was a bit of a cover up. I’m convinced the FiA felt that was a better outcome than going public with what would become a real concern about future safety. The cars didn’t have big enough fuel tanks to allow racing without refuelling so they were in a bit of a corner. Does not right a wrong but I learned a lot about politics that year!!!!!

At the time though the team boss was not “flavour of the month” with the engineers who felt he’d rolled over too easily. I felt that way too. However, looking back now and knowing the power that the FiA have, the boss would have put the very existence of the team at risk if he had let the technical people go ahead with their defence and effectively told the FiA to go and get stuffed (as they say). I guess he felt he was managing that risk – knowing that the team were likely to win the championship if he played ball with the rule makers.

The fire burned for about 4 seconds only - although it seemed much much longer. The man doing the refueling had the worst burns as fuel sprayed onto his helmet dripped inside via the air gap at the top of the visor. He has made a full recovery. The driver was next with a similar problem but not as severe. A number of the crew were seen stumbling backwards to get away from the fire while pointing their fire extinguishers at their colleagues and the sources of the fire. That's why just seconds.

Back at the ranch. In the meantime, inside the Benetton team, a reason was being created for the team not to discuss their close relationship with Ligier. In order to help Ligier out, track performance wise, without spending a fortune, an agreement was reached to provide “technical assistance”. We were asked to provide certain pieces of design related information. I was not happy to give the info but, as an employee, you don’t always have many choices. One can leave the team of course and that’s what I did a little while later when there was a “last straw” moment - this was one of my reasons for being unhappy with how things were going.

Anyway the resulting help that was given led to Ligier people coming and working at Benetton to make parts – from our moulds! Strictly not correct and really upset a “few” people (inside the company). They arrived in full team clothing which is what created a stir inside the company. So to hide where they came from internally (totally unsuccessful) they were given some Benetton clothing. That pissed the workforce off even more as this was not a privilege given to the guys in the composite workshop they worked beside. That may be one reason why the team didn’t want to immediately disclose that Ligier had a letter from Intertechnique as the team really didn’t want the closeness of the working relationship to come out in full! That would have been another day in Paris to see the headmaster – and would not have ended well for either team!

What justification was there? I recall being told at the time that Ligier were in trouble and that our help would only bring them towards competitiveness, not more. This was certainly perceived as a lower cost way for whoever had put money into buying the team to provide an improvement than funding independent research, but regrettably it was almost certainly outside the law. Intellectually I understood the motives but emotionally I was (very) upset by what the team did. When I got a phone call offering me a dream job elsewhere I said yes where normally I would not have been interested. Having finished the rollout car design for the following year I resigned (with other reasons as well of course).

Photos Copyright Arthur Thill – World Press

More information available via Wiki (I've not contributed to this) here

More posts from me here https://www.linkedin.com/today/posts/willemtoet1

Above link is to a pretty good summary video of the different cameras that were covering the pitstop. They show how quickly the team reacted to put out the fire.

Update after publication (6th April). Feedback from former colleagues adds further information including confirmation of the information I've presented and a bit more which I will share here. After the incident - and as you can imagine - many days of testing was done back at the Benetton race team factory to try to replicate the problem. In part this was to prevent the chance of any future incidents as at Benetton in particular NOBODY wanted anything like this to happen again. From what was learned at the time the only way the team could replicate the problem was with a small ball of rubber (the size of a typical rubber "marble" thrown from the F1 tyres of the day) stuck in just the wrong place on the car's refueling coupling. The conclusion was that this was actually the most likely cause of the problem as it allowed fuel to escape before engagement of the full mechanism. If the problem was caused by the small particle it would have needed engagement followed by removal and the jam. This second bite at putting the nozzle in place was fairly commonplace if the system didn't align properly. However, normally if this happened, the valve held by the refueler would not open. These second bites at the cherry would happen more often if the driver was significantly out of position so the refueling hose was at the wrong angle. I'm waiting to hear back if we have more details about this.

Another piece of info to come back was that the filter was removed at the behest of a very senior member of the team (not a "junior" person as stated at the time). No surprise there! I knew it but had not specifically mentioned it. Also the filter removal made no measurable difference to flow speed.

What was learned here was passed onto the FiA and to the TWG (technical working group) and the rules changed for the following year to include a cover for the fuel filling mechanism on the cars so that the little ball of rubber problem could not happen. I remember that and had forgotten the research that led to it.

Thanks to my former colleagues for your feedback (private so no names and very useful to receive).

More posts from me here https://www.linkedin.com/today/posts/willemtoet1