Fatally Flawed

There is an organization that investigates air crashes, one for rail and a maritime investigation organization, but who investigates car crashes? Got it in one, nobody! Accident Investigation plays a vital role in air, rail and accidents at sea, even though there are far fewer accidents in these forms of transport, with lower loss of life and serious injury. There are Traffic Accident Investigators who must have investigated 1000s of accidents, and for a fee will reconstruct the events of an accident, none it seems have ever found a fatigue failed shaft. This is indeed strange given that there are 10s of millions of these shafts in use each day , all undergoing the stresses necessary and given a minor defect in manufacture, the possibility to fail in fatigue. Indeed in a current action in America involving 250 deaths, it was company records that revealed the fault in these vehicles not the Accident Investigators. There are organizations who test the crash worthiness of cars and the survivability in the event of an accident, but none are know, who test why the car crashed in the first place. There is an unhealthy assumption that all crashes have either driver error, badly maintained cars or road and weather conditions. There is another school of thought which believes that roads and their design and maintenance has a part to play in accidents, this is no doubt true, the accident that this site refers to, the road had a part to play, had this road been straight and no swerving action taken place this accident would have waited until the right condition applied i.e. one where sufficient side force was applied to ensure the bearing failed, allowing the wheel to come off. Yet another school and this is undoubtedly true believe young inexperienced drivers are more likely to have an accident, they are also more likely to have an older car and this is just the group of cars that are prone to this type of failure, together with company representatives and light van drivers who cover a large milage each year. Cars in Britain are subject to an annual test, as they are in many other countries, these tests start when the car is 3 years old, this test seems to discover the minor manufacturing defects in cars and seems to be largely responsible for recalls to get these defects fixed, however the defect that this site refers to, was present during a number of these tests, which failed to detect this fault and no amount of testing would detect it. No amount of pulling and pushing by a garage mechanic would detect any play in a wheel even if the shaft were fractured through and just the bearing held the wheel on. So the most critical component on a car could be failed and the annual safety check would fail to find it. Now the received wisdom is that these shafts fail because they are impacted, and that the driver is to blame, so nobody is looking. parallel this with one Harold Shipman who unmonitored dispatched, it is believed as many as 500 of his patients, or take the case in the USA where over a period of 15 years, 300 corpses lay uncremated and undetected. Clearly there is a distinct lack of research on the subject, in fact remove this modest effort and it amounts to nil. This type of failure, "Deathtrap Beetle Syndrome" has the following associated events, a prolonged and at first slow crack propagation, somewhat speeded up before final failure until the integrity of the shaft is lost, the wheel then is totally retained by the wheel bearing, which will remain intact until the side force on the bearing causes it to separate, which it is designed to do in order to fit a replacement, this can be done with a piece of tube and a 2lb hammer on the bench, so a one ton car and a sharp bend will do the job just as well. Many who would claim to be accident investigators, have little experience in the failure modes of materials, their skill depends on finding worn components, lack of maintenance, speed, in other words, it's down to the driver yet again. There is a long-standing belief that all shafts fracture because of impact damage, this may have held true for stub axles of years ago. Today's driven shafts are under totally different load conditions. World-Wide in the event of an accident the first to arrive to assist are the Police, they are the ones who invariably investigate the "cause" of an accident, usually in the event of a fatality. How many of these Police investigators even know about fatigue failure, let alone could identify it. In Britain as in some other countries the Police fill out a STATS 19 form, this is done by an attending officer, who's engineering skills could be a brief encounter with Leggo as a 3 or 4 year old, yet the whole drive for safety is based on these figures. These STATS 19 forms are compiled by a committee made up of members of The Police force, Local Highway Engineers, various Members of Regional and National Government and other members from the DETR, there is no mention of a mechanical engineer among this committee. Indeed if one where to put forward suggestions that mechanical defects associated with manufacture should be included, there is no one to investigate this defect should such a requirement be sought.

This web site along with all pictures are © David Bailey 2002