Many will know this quote:-
For Want of a Nail
For want of a nail the shoe is lost;
For want of a shoe the horse is lost;
For want of a horse the rider is lost;
For want of a rider the battle is lost;
For want of a battle the kingdom is lost;
And all for the want of a horseshoe nail.
This perhaps one of the earliest exhaltation to preventive maintenance, but is also an example of how problems can have root causes many levels down the chain. Despite most of us knowing this poem, we all have a tendency, on identifying the most visible problem will immediately deploy efforts to solve it rater than lookign for the root cause (in the case of Herbert – poor equipment maintenance).
In truth a very simple method to trace down to root cause is contained within Herberts verse ; The 5 whys. By being a little cautious of the obvious and asking “Why” one can dig down and obtain a better understanding of the source of the issue. There is of cours enothing magic about 5 – it could equally be 3 or 7. In Herberts verse one could ask another why
- why was there no nail, and perhaps the answer would be that the nail delivery did not arrive
- why did the nail delivery not arrive; the answer could be that all the waggos were comandeered for the war effort.
So where does one stop? However there are 2 rules:-
- Ensure there is some real evidence at each level so the process does not go off on a tangent.
- End the process when
- several problems have the same root cause
- the root cause is very basic
- as in the above case the process indicates a circular cause
Once one has a candidate for the root cause then work on it and check the result in good PDCA fashion.
Read the following for more details on the 5 whys