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Porsche 911, System-Safety, and the role of managing changing risks

The original Porsche 911 (1964-1973)

In my 18 years of working with Human Factors and System Safety, I have often come across questions and subsequent discussions of the following kind:

· What is the difference between Safety and Quality?

· What can this System Safety (or Human Factors) approach do for us?

· Is it really worthwhile to go through Management of Change processes?

It is my experience that narratives with illustrative examples are the most effective way of delivering messages on this topic. Luckily my more recent fascination with classic cars and especially the beautiful early Porsche 911´s brought me on to a perfect example that covers all the three questions above. So, join me for a little journey back in car history through the System Safety lens.

When the Porsche 911 was introduced in 1964 it obviously was the most recent offspring of the Volkswagen Beetle and its sporty cousin, the Porsche 356. All of them featured the same basic construction principle of having a rear mounted and air-cooled engine basically hanging out behind the rear axle and providing its power to the rear wheels.

This had originally brought many advantages in terms of being a relatively simple yet very reliable construction and simultaneously allowing for a roomy interior. Having spent much of my childhood in Switzerland I can attest to the Beetles popularity in the mountain villages. The weight over the drivetrain provided reasonable traction and while roadsides were regularly populated with boiling engines, the beetle would just do its job.

While the construction principles remained, the applied power on the other hand increased dramatically. A regular Beetle would come with 34 hp and also the four cylinder 1,6 liter of the Porsche 356 with its 90 hp did not yet alter the driving characteristics dramatically. The 911 however came with a completely new 2 liter, six-cylinder sports engine and for its time impressive 130 hp.

Applying so much power to a car that weighed less than 1000 kg without any electronic helpers as we know them today, became a “nice challenge” for its owners. Especially in damp road conditions the car would display its tendency for sudden loss of grip, when too much power was applied. The result would be a spinning car at best and a fatal crash at worst. This was not unlikely to happen since effective crash protection including seat belts had not yet entered the stage.

What followed in the coming years were a long range of attempts to remedy this obvious safety problem, that initially was threatening the success of the car and consequentially the existence of the company. At that time the 911 was the only model Porsche produced.

The first remedy was to install two lumps of cast iron/led weighing 11 Kg into the front bumper in order to provide more counterweight to the front. While this solution may have relieved the problem somewhat it obviously also was an embarrassment to all engineers, who had spent years refining a sports-car to achieve the best possible power to weight ratio.

A few years later this solution was hence scrapped in favor of letting two batteries move all the way to the front, directly underneath the headlights. The result was not yet satisfactory and the persisting handling problem was aggravated by the fact that the engine department was about to put out even more powerful versions, both through tuning efforts and soon by increasing the engines volume.

In 1969 a substantial step was taken by partly re-designing the entire frame and lengthening the wheelbase by 5cm to provide more stability. This was a successful step, but by 1971 the car was to support a 2,4-liter engine with up to 180 Hp. Consequentially the race to even out the weight distribution continued.

The 911´s fuel inlet on the front left side

The original oil inlet to the rightunder the hood

This led to another significant idea for modification. While the engine type is known as air-cooled, a substantial part of the cooling is actually provided by oil. This means that even a small 2-liter engine has an oil sump that contains 10-11 liters of engine oil. The idea was now to move this container forward, so its weight would reside in front of the rear axle. From a driving dynamics standpoint this would be brilliant and also it would not impair the functionality of the engine.

There was however one significant step to be included in this modification. The oil refill inlet would move from its original position inside the engine room to a little exterior “hood” placed just below the right rear seat window – receiving the name Ölklappe. Knowing their vehicle inside out none of the engineers seemed to consider what potential confusion this perfect engineering solution would create, once released into regular public use. This because the gas tank had retained its Beetle heritage and was placed at the front of the car with the gas refuelling to be performed at the front left side.

The Ölklappe below the right rear seat window

So, in 1972 the Porsche 911 Ölklappe model was released and the results were soon emerging. At this point in time most gas-stations were still manned. Personnel, who was not necessarily accustomed to this still rare and exotic car, on a regular basis filled gas into the engine oil inlet. Also owners are said to have gotten the inlets confused. This was always accompanied with the catastrophic outcome of a total engine failure, sometimes probably creating additional safety hazards, if the drivers had just sported their cars back on to the motorway.

Manned Gas stations of the era

Seemingly no one had assessed, what new risk could be associated (Management of Change) with introducing this new engineering solution. A solution that in itself would work perfectly to solve its purpose of improving the cars handling and was executed exactly to its specifications (Quality). Yet it had devastating implications (Safety & Operability) . The main reason for this was that it had not been considered what human and organisational context the technology would be released into (System Safety).

The news regarding the problem of course soon hit home and the response was immediate. In 1973 the oil-refill inlet wandered back under the hood of the engine room, where it has stayed up to this day.

In my safety-work, I have come across countless examples that resemble the above scenario. Regardless whether energy-sector, healthcare or aviation the same type of problems have surfaced when technological changes were introduced without understanding how the professional work was actually done. So even though we look back some 50-60 years in time, the topic remains persistently current. Most such examples for reasons of confidentiality cannot be discussed in public domains. Consequentially this story serves as a powerful little conduite for opening reflections and discussion around the three initial questions to me.

I hope this has been useful and maybe even a bit entertaining for you as well.


Marcian Tessin


From today´s perspective there are two interesting twists to the story.

Firstly, the difficult handling of the 911 eventually never became a constraint in terms of its success. Social acceptance of risk was much higher than today and instead it was seen as a trademark of skilfulness and courage to be able to tame the beast.

Given that Porsche production numbers were fairly small at the time, the 1972 Ölklappe is now very rare and one of the most sought-after collector items of the first generation 911.

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