Advances in Engine Reliability Mean Greater Importance for Preventive Maintenance

Aircraft mechanics just starting out in maintenance today find it hard to believe just how frequently engine problems used to develop that required emergency landing or, worse, resulted in incidents or accidents with injuries and loss of life. This was true for four-cylinder single engines on Piper Cubs, as well as large, multi-cylindered radial engines — what we call in the industry big, round engines — used by airliners.

When I was first working as a mechanic in the 1960s and ‘70s, major engine repairs were commonly performed in the field. My first tasks as an airline mechanic were to replace blown cylinders on big, round engines, specifically Pratt & Whitney R2800 and Curtiss-Wright R3350 engines. In a typical work week, as a new mechanic, I would change cylinders three or four times. I can’t begin to count how many cylinders I changed in those early years but they were literally in the hundreds. I changed cylinders so frequently that I didn’t have to bring my whole toolbox up when I climbed on top of the engine; I knew exactly which tools I would need. And, yes, changing cylinders was a dirty job, which is why those tasks were usually given to the new mechanics.

 

Improved reliability

Today’s young mechanics are unlikely to have to worry about changing cylinders — or any of a number of other jobs we used to do routinely, like adding oil because the engines consumed so much and leaked so badly. On a typical flight across the country from the east to west coasts, it was not unusual to add 10 or more gallons of oil per engine. Now, improved engine reliability has made these tasks extremely infrequent.

That improved reliability came about as a result of a multifaceted effort by the aviation industry and the Federal Aviation Administration beginning some 50 years ago and continuing to this day. This included engine design changes, changes in materials used in the construction of the engine and its components, and changes in engine operating procedures.

One of the most significant improvements has been in the lubricants used. Today’s lubricants can be synthetic blends or fully synthetic with properties that not only reduce friction but also provide better coatings to reduce engine wear and also transfer heat better to reduce operating temperatures.

Preventive maintenance

While new mechanics may not be changing cylinders or adding engine oil in the field the way we used to, they will still have a critical task to perform related to engine reliability. And that is in the preventive maintenance area which has become more significant today especially with regard to lubricant analysis. Whereas in the past, oil changes were infrequent because the oil was replaced so often; lubricant changes are now an important part of maintaining engine reliability. Lubricant samples from an engine, when analyzed by a specialized laboratory, will provide important information about what’s going on inside the engine. And that information will be used to better schedule required maintenance and improve engine reliability.

 

John Goglia has 40+ years experience in the aviation industry. He was the first NTSB member to hold an FAA aircraft mechanic’s certificate. He can be reached at gogliaj@yahoo.com.

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