SPUR GEARS

Aircraft maintenance, like medical surgery, is of two categories — major and minor. But unlike surgery, aircraft maintenance has only one result, SUCCESS.

You can’t fail, you can’t be unsuccessful. The ‘zero error’ philosophy is astonishingly true in aircraft maintenance. Most aircraft maintenance personnel are perfect in their job. But a few, a very few can tend to err.

There is another side to this. Those who are perfect in their job may be ‘failures’ in other fronts of life. Not everyone, but some.

One cannot be perfect in all spheres of life; somewhere he has to err. The right choice of the erring sphere makes one SUCCESSFUL.

My hot coffee was annoyed with me for not caring for her for long and turned cold quicker than ever. I still sipped. The hangar canteen ‘hustle-bustled’ with various types of sound frequencies which can be classified in the scales of C minor, D major, F minor, F major and many other unclassified frequencies emanating from various mouths. A group of young engineers burst into the executive dining hall with differently shaped ‘bajjis’ (an Indian snack) in their hands. They occupied the table next to me and discussed how zero-emission was possible for aircraft engines. I finished my once upon a time hot coffee and walked out of the canteen.

I am in the Major maintenance division or Base maintenance division of our company.

The engine ground run (we affectionately call EGR) was over by that time. The AME presented his head along with a fancy cap over it through the sliding window and yelled at me, “#1 Engine DRIVE light”. I yelled back from beneath, “don’t worry, we have time, departure tomorrow morning only”. He withdrew his head along with the cap back into the cockpit and slam closed the sliding window.

‘DRIVE’ light comes ON when the Integrated Drive Generator (short form IDG, which is nothing but a combination of AC generator and a constant speed drive to produce electrical power for the aircraft at a constant frequency of 400 Hz) develops some faults. IDG is a complex component with a generator part and a constant speed drive part, both integrated together to be rechristened as IDG.

IDG is different from the other components of an aircraft engine. It is special. IDG functionally belongs to the AVIONICS (aviation electronics) group but is maintained, rather pampered by the MECHANICAL group. It is similar to a rich child of very rich parents and is taken care of by the maids.

The complexity of IDG is in the Constant Speed Drive portion. It is a Hydro-mechanical component, filled with oil and numerous gears arranged in numerous ways. I like gears. They are the most pleasant parts of a mechanism. Whenever I look at them, it seems that they smile at me, showing all their teeth. Very pleasing creatures. I like gears. I like spur gears the most. They are so simple, closely moving and always smiling. They are examples of good relationships.

But Bevel gears. I don’t like them. There is something oblique in their approach. They do not have a straight approach. They are like an illegal relationship. Though they are together always, they are never on the same plane. I hate Bevel gears.

Two junior technicians opened the fan cowls of the #1 engine to access the IDG. The senior technician went near the IDG and stared through the sight glass and told me “it is overcharged”. The oil level was above the ‘DRAIN’ mark. He then drained some oil into a beaker and smelled it. He is an experienced technician. He knows that illegal mixing can create problems. He showed the beaker towards my indifferent face. I put more than half of my protruding nose into the beaker. I smelled FUEL. Illegal mixing.

The culprit was the fuel-oil heat exchanger for the IDG. We replaced the fuel-oil heat exchanger as well as the IDG. And I called it a day.

At home, I had some guests waiting for my arrival. A husband and wife. The husband is a distant relative of my wife. They had exhausted almost all the topics which can be shared with my wife. When I reached home, they became very happy and synchronously stood up. I greeted them and we all smiled. After some smiling and chatting ordeal they bid goodbye. As they were walking towards the gate, I noticed that the husband is very tall and the wife is very short. They walked closely, rubbing each other. They are spur gears. The smaller one is the ‘DRIVER’ and the larger one is the ‘DRIVEN’.