Friday, August 13, 2010
Technical diagnostics for a safer journey
From my article "Technical diagnostics for a safer journey" for the journal Spectrum
One of the most important properties of a transport system is safety. It’s said that the human factor is the main reason for many transport accidents, from aircraft to bicycle.
That means there is more chance of an accident occurring because of a simple mistake of the operator (driver or a pilot), or because of the engineer who maintains or repairs the vehicle, or the other people who involved such as the air traffic controller or the policeman on roads.
This article is focused on the engineering side, more precisely about identifying problems in mechanical part or a structure. What do engineers do to minimise the probability of having a failure?
Technical diagnostics, we all have heard this word very often in medicine. Over there, diagnostics means, identification of the nature of an illness or other problem by examination of the symptoms. The Buddha tried to found the reason for sadness before cure, doctors search for reason of an illness before the cure. The engineers do check and evaluate machine parts before thinking of a way to remedy it.
There are a certain type of engineers who make their living only by inspecting structures or machines. They are usually called NDT or NDE engineers. NDT stands for Non Destructive Testing (NDE-Non Destructive evaluation). NDT is the branch of engineering concerned with all methods of detecting and evaluating material defects.
A small flaw can grow into a huge crack due to time because of uneven loads. Flaws above the limit can lead to loss of strength, thereafter to a major structural failure. (For example, the aircraft wing can have different loads in different flying conditions. Or wheels can have different loads because of the road conditions and speed variations).
Therefore, the NDT is important in guaranteeing safety of operation as well as in quality control.
The engineers’ task is to identify those flaws with specific equipment. Thus it is very important for engineers to have a wide range of knowledge about what they should look for.
Sometimes it’s almost like searching a blind alley. Patience is essential. It’s a kind of a meditation. Aircraft and bridges don’t fall and ships don’t sink because of these engineers. They are the heroes behind the scene.
This is one of the most important parts of engineering which is closely related to aerospace engineering, civil engineering, electrical engineering, material science and engineering, mechanical engineering, nuclear engineering, petroleum engineering the physics. It’s often used in the constructional and service sides.
We would need many talented engineers who can offer their services to ships and aircraft which are about to touch our motherland.
There are several functions in technical diagnostics. The first is to determine the present condition using NDT methods.
As the second function, the engineer finds reasons for defects with the help of his education and knowledge.
The third is the prognosis. As in the weather forecasting, engineers use statistical data to determine the life or machines and possible future failures. For example, vibration of an aircraft engine can be very informative.
In my first research in this field, I was quite surprised to see that the vibration of a whole engine can represent aerodynamical information of a single blade inside.
Therefore, by watching statistical data of vibration, the engineer determine internal problems and can give accurate predictions about the lifetime of an engine.
The final function of technical diagnostics is genesis. These are mostly about crashes or an accident. I was lucky to listen to some lectures of an aircraft crash investigator. He travels around the world where aircraft catastrophes took place.
It’s the worst job when one sees many dead bodies all around, although, at the end of the day someone has do this. They usually take evidence of all aspects. The most famous source of evidence is the black box (The flight data recorder.) In fact so called “black box” is a fire/shock/water proof “orange box or a ball” with a recording device inside. It is usually situated in the tail of an aircraft............ Full article can be found at,