This is a quirk of Italian law, and if death occurs, it must be held accountable even on the track. During the 1994 San Marino Grand Prix weekend, the tragic deaths of Roland Ratzenberger and Ayrton Senna resonated with the world and brought Formula One 1 to a rigorous scrutiny.

Although Latzenberg's accident was apparently caused by the failure of the front wing, Senna's accident became the subject of crazy speculation. When the FIA ​​tried to find lessons from the death toll that could translate it into effective safety improvements, the Italian legal machine followed, and a criminal trial followed.

Prosecutor Maurizio Passerini's case focused on determining the shearing effect in the Senna FW16 steering column put him in the corner of Tamburello and into the track on the wall. Passerini appointed Professor Enrico Lorenzini, Dean of the School of Engineering at the University of Bologna as an expert.

Lorenzini ordered the column to be analyzed by two teams of experts from different agencies so that results can be compared and correlated.

Part of the investigation was entrusted to the Air Force Research and Experimental Department of Platiga Dimar, near Lazio, while the other part was entrusted to the Metallurgical Laboratory of Industrial Chemistry at the University of Bologna. Both teams used SEM - scanning electron microscope - the most advanced tool of the time.

Thirty years later, Motorsport.com managed to contact Gian Paolo Cammarota and Angelo Casagrande, two professors at the University of Bologna. They are still friends and still meet occasionally.

Cammarota and Casagrande

Photography: Racing Images

Born in Milan in 1936, Cammarota is now retired, allocating his time to Bologna, Venice and Germany. A slim, reserved man who carefully weighs every word.

Although Cammarota specializes in industrial chemistry, Casagrande in Bognese is still part of the teaching staff at the Metallurgy Academy.

"We are now phased out SEM - more modern and advanced investigative systems exist - but scanning electron microscopy provides us with clear, undisputed answers in the Senna case."

In the original design of Williams FW16, the steering column is a single piece metal tube with a length of 910.2mm connected from the steering box to the steering wheel hub. At a distance of 685.5 mm from the lower end (steering box), the column is connected to the chassis by aluminum alloy support and comes with a self-lubricating bushing made of Teflon-like material, the remaining portion (224.7 mm) is 224.7 mm long - as a cantilever.

Senna complained to the uncomfortable team in the cockpit: he wanted to lower the steering column to improve his driving position because his knuckles rubbed against the top of the chassis when using the steering wheel design he liked, and the result was painful. This is not an easy task, as regulations require that once the steering wheel is removed, the cockpit section must have sufficient clearance in the cockpit section to pass through the 250mm x 250mm template according to the 1994 FIA rules.

To satisfy Senna's wishes, Adrian Newey, Williams' chief designer at the time, directed the drawing office to lower the steering column by 2mm. When it was discovered that this would grab the FIA ​​template, the next best solution was to reduce the column diameter to 4mm of that area.

“Reducing the diameter of the tube is a major design error,” Camarota said. “The chemical and mechanical properties of the parts are inconsistent – ​​they clearly show the use of two different materials.”

The modified column is divided into three parts, two parts are made of T45 steel, with an outer diameter of 22.225mm, a wall thickness of 0.9mm, and an outer diameter of 18mm, with an outer diameter of 1.2mm. The parts are welded together.

Senna was uncomfortable in his FW16, so it was modified

Photography: Racing Images

Franco Nugnes: What tests have you performed?

Gian Paolo Cammarota: We performed shallow metallographic analysis, followed by internal and external roughness tests and fractal checks. Chemical analysis was entrusted to CERMET.

In the expert report submitted to the court by Professor Lorenzini, it wrote: "Generally, it must be said that the modification of the three-piece steering column shows that due to the thinness of the part at the maximum pressure point, at the maximum pressure point, a sudden change of the crossing part, a sudden change of the excessive flakes of radius and a certain marking process, and a certain demarcation process, and a certain demarcation process, and a certain demarcation process, and a certain demarcation process, which can demarcate a demarcation project. Therefore, high risks occur under static load and dynamic fatigue.

By the way, on the external and internal surfaces of the joint, obvious circumferential markings of the machining tool can be observed, so the outer and internal surfaces of the tube exhibit surface surfaces of components that are not suitable for running under fatigue under extreme experimental conditions. ”

fn: Can human error occur during welding?

GPC: I'm excluding it. I showed our images to Professor Horold Herold of the University of Magdeburg, who is the leading expert in the field, and he assured me that the welds were perfect. The problem is entirely that the cross-section of the test tube is reduced precisely at the position where the stress reaches its maximum.

fn: So why does the steering column fail?

Angelo Casagrande: It was damaged before the Grand Prix began. In short, there is a crack (a thin, usually thin one before rest) that is progressing and formed before the game where Senna died. The existence of oxidation does not allow us to determine exactly when the fatigue phenomenon begins, but we are enough to understand what is happening.

fn: In Formula One, the best material available is usually chosen - what might be wrong?

AC: They made unplanned modifications. The shaft and cantilever parts are so sized that even with supermatter it could last a game. Then, if not replaced, it will fail because it cannot withstand the pressure. Reasoning the material without meaning: This is a serious factor, but the metal is not done well given the size and structural characteristics of the components.

Engineering experts spent a week examining the remains of Senna's car

Photographed by Rainer W. Schlegelmilch / Motorsport Images

fn: How long do you have a steering column?

GPC: In less than a week, we returned it. Only enough time to take the SEM exam. Engineer Danesi was always present during the analysis, representing Williams.

At first, the British team didn’t want to hear anything about fatigue, but we immediately saw the failure and had to evaluate how much damage the tube was due to fatigue and the tear.

fn: The survey also includes roughness tests...

GPC: Roughness is the ratio between the groove and the surface. If the value is high, serious trouble can occur.

In aerospace, all surfaces must be polished to mirror effects. When the fatigue threshold of the material is exceeded, there must be no stripes that can concentrate stress and become the starting point for surface change.

On our column, there is only partial polish on the outside - which should have been done in the mirror - and inside, nothing is done at all. The crack must have started from the inside and may have been in the process of practice.

There are three parts in the tube: one shows fatigue; the middle part shows a mixture of fatigue and ductile fractures, which is expected when the material is very difficult. In the third part, there is clear evidence that catastrophic fractures are caused by the effects on the wall.

fn: The team removed the carbon fiber layer and cut off part of the chassis coverage. Do these interventions reduce the stiffness of the bike and can promote steering column breakage?

GPC: It is possible, but this problem was not resolved in the trial. The reproduction of cracks may accelerate - we need to know exactly when the cracks begin.

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Check Newey's role in trial

Photographed by Rainer W. Schlegelmilch / Motorsport Images

The criminal trial is broad, accusing Frank Williams, Patrick Head and Adrian Newey, as well as FIA official Roland Bruynsereede, race organizer Federico Bendinelli and Imola Track Manager Giorgio Poggi, from Culpable homicide. As it progressed, Passerini moved away allegations against Williams, Bruynsereede, Bendinelli and Poggi, focusing his attention on Head and Newey.

Once it had the steering column and recognized the fatigue crack, Williams built a test rig to determine if the column was strong enough to transmit the steering input at the required torque, even in a weak state. Its findings indicate the situation.

The TV footage clearly shows that the rear end of the Senna car stepped out before his car left the track, which is inconsistent with the prosecutor's argument about the failure of the steering and caused the car to rise directly. It is impossible to prove that failure is the cause or effect of the accident - so, right, head and Newney were acquitted and subsequently tried to appeal the decision failed.

The lessons of Imola not only inform the FIA's ongoing safety program, but also influence the process of automotive design. Williams, for example, proposed a system where safety-critical components can be signed only after experienced stress engineers have signed the design.

"It is an inescapable fact that this is a bad design that should not be allowed to get on the car," Newey wrote in his autobiography.